"" ""Tr‘.--J. L—r‘ )— ?? commzsom 0? Panama? _: ' AND wARBLmoNE THRESHOLDS ' *Thesis for the Degree of PhD. MICHIGAN STATE umvmsm . ' ' WAYNE JOSEPH .STAAB' _ 19.71 , This is to certify that the thesis entitled COMPARISON OF PURE-TONE AND WARBLE-TONE THRESHOLDS presented by WAYNE JOSEPH STAAB has been accepted towards fulfillment of the requirements for Ph.D. dPgreein Audiology and Speech Sciences ,0 90% Date 24/37.,” norm: W 233 3 a 7" ABSTRACT COMPARISON OF PUREFTONE AND WARBLE-TON E THRESHOLDS By Hsyne Joseph Stssb Herbie-tone stimulus parameters of frequency deviation and nodu- lstion rate were investigated to deter-ins their effect on hesring threshold. Three noreel-hesring experienced listeners were presented with thirty randomised combinations and thirty repeated eessures (for s total of sixty) warble-tone frequency devietions and modulation rates. Using e sinusoidal base frequency, thresholds were measured for the following frequency deviations: t1. 3, 6, 10, and 50%. The sodulstion retes investigated were: i. 2, h, 8. 16, end 32 per second. The thresholds obtsined for eech of six octeve frequencies from 250 through 8000 Hz were then coepsred with the same subject's conventional, pure- tone sir-conduction thresholds. Inch subject's hearing threshold levels were meesured nonsurelly on six seperete occssious. with one frequency tested per session utilising e 2 dB step'descending method. In general. substentisl egreelent was found between wsrble- end pure-tone thresholds. However, differences were found for some stimulus persmeter conditions. These differences varied by test frequency and warble-tone combination (frequency deviation end nodulaticn rate). The Hayne Joseph Staab results demonstrated that changes in frequency deviation had a greater influence on threshold than changes in modulation rate. This was particularly noticeable for the 150% frequency deviation conditions. while threshold changes related to frequency deviation were not consist- ent across frequencies, lower aodulation rates generally resulted in better thresholds for a given frequency deviation at all test frequencies. Two ”changeover” regions were observed with respect to the types of warble-tone patterns. one between 250 and 500 Hz and the other between 1000 and 2000 He. The direction of threshold response reversed in these regions and was most noticeable with wider frequency deviations, e.g.. from 110% to 350%. That is, warble-tone thresholds were better than pure-tone thresholds at 250 as, poorer at 500 and 1000 Hz, and were better again at 2000, #000. and 8000 HI. Poorer thresholds generally were found with lower modulation indices (frequency deviation divided by modulation rate) for .11 frequencies and frequency deviations. In contrast to previous investi- gations, no evidence was found to support the notion that one or a combination of aodulaticn indices provides a guideline for threshold prediction when testing normal hearing adult listeners. Intersubjeot reliability of warble-tone thresholds was good (p. s. 0.05). In addition. variability in warble-tone thresholds was small with the exception of 8000 32. In general. warble-tone combinations up to and including frequency deviations of ti” and modulation rates as fast as 32 per second resulted in close agreement (15 dB) between warble- and pure-tone thresholds for normal hearing adults. . GOHPABISON OF PURE-TONE AND UARBLE-TONE THRESHOLDS By Hayne Joseph Staab ATHEIS Submitted to Michigan State llnivereity in partial fulfill-em. of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Audiology and Speech Sciences 1971 ACKNOWLEDGMENTS The writer wishes to express appreciation to Dr. Hilliam F. Bintelmann for his guidance as thesis adviser, and also to Dre. Herbert J. Oyer. Daniel 8. Beasley. Oscar I. Tosi. and Donald A. Burke for serving as thesis committee mesbsrs. Grateful acknowledgement is also extended to Dr. Judith P. Frank-ann for her assistance with the statistical aspects of the study and to Hr. Donald B. Riggs for his technical assistance with the instrumentation utilised. In addition. appreciation is extended to lies Ellen K. Smitley and lies Sabina A. Kurdsiel for serving as two of the three subjects. Special gratitude is also due my wife. Lou. for her encourage- ment and assistance in preparing this ssnuscipt and for serving as a subject. Likewise, special gratitude is due four daughters who deserve more attention from their father than he has been able to give them these past years. 11 LIST OF TABLES . e TABLE OF CONTENTS LISI‘OFFIGUREOOOOOOOOOOOOO LIMOF‘PPMICEOOOOOOOOOOO Chapter I II III IV mRODUcrIONeeeeeeeeeeeeee larble-Tone As An Auditory Stimulus Statesent of Purpose WMOFTHELHBATUREOOOOOOOOOO larble-Tcne for Threshold Determination. Coaparison of warble-Tone and Conventional Pure-Tone Thresholds Weeeeeeeeeeee mmumocsnunm SubjectS......... Instrumentation e e e e e e Haico HA-Zb Audiometer Currently Oscilloscope and Spectrum Analyser Function Generator . . Voltmeter e e e e e e Frequency Counter . . Beat-Frequency Oscillator Test Environment Calibration........ “1.1111 EPIC,“ e e e e e Experimental Procedures . . Threshold Determination Pure-Tone Threshold Tests Harble-Tone Threshold Tests Ambient Noise Levels in Test Room REBUDTS AND DISCUSSION e e e e e . e Pure-Tens Threshold Results Herbie-Tone Threshold Results Harble-Tone Thresholds versus Frequency 111 Herbie-Tone Stimulus Phraaeters UBsd V warble-Tone Versus Pure-Tone Thresholds Relations Along Harble-Tone Threshold flaking: by SUDJOCtB e e e e e e e e e e e e e e e e e ercts of Hodulat ion Index on warble-Tone Threshold e e e e e e e e e e e e s e e e Discussion e e e e e e e e e e e e e e Trends in warble-Tone Thresholds Cosparisons with Previous work . Role of the Modulation Index . . Sum-Ir! e e e e e e e e e e e e e e e SUMMARY. CONCLUSIONS , AND RECOHNUDATIONS e SUI-‘1! e e e e e e e e e e e Conclusions e e e e e e e e e e Beconendations for fixture Research . LISTOFRE’MCB ................. APPUDICE 1v “7 53 55 61 63 68 68 69 7O LIST OF TABLES Table has 1. Combinations (c) of frequency deviations (1st subscript) and modulation rates (2nd subscript) utilised to produce the warble-tone at each test frequency. The table shows th‘t repeated IOCIUIOIOUtI were ObttinOd-e e e e e e e e e 31 2. Honsural. descending pure-tone air-conduction thresholds obtained during each test session for each subject at six frequencies along with the mean an (ANSI-1969) and SPL thIQBhOIQ V‘lflOB s e e e e e e e e e e e s e e e e e e 35 3. Ilean* warble-tone dB difference thresholds from the pure-tone thresholds and standard deviations for each tCCt ff'guCDOI e e e e e e e e e e e e e e e e e e e e e e u? 4. Summary of coefficient of concordance (it) of inter- subJeot reliability of warble-tone thresholds . . . . . . 5“ 5. Mean warble-tone threshold difference (TD) in dB from the pure-tone threshold along with the modulation indices (n1) for each of the warble-tone ooobinotiooo used . . . . 56 A1 . Octave band and 0-soale analyses of ambient noise levels in exaaination room (fan on) in dB SPL according to the standards set forth by the American Standards Association (‘3‘ 33e1'1960)e e e e e e s e e e e e e e e e e e e e e e 77 A2. Pre- and post-experimental linearity of Ilaico NA-Zh sud ioseter attenuator made acoustically at the test earphone e e e e e e e e e e e e e e e e e e e e e e e e e 8“ A3 . Pro-experiment and iometer earphone output data for the right earphone of tho hico HA-Zh audiometer for (i) tho output seasured for the pure-tone stimuli. and (2) the output measured for the unmodulated warble-tone stimuli center frequencies. The pure-tone measurements were aade according to the Aaerican National Standards Institute (ANSI 33e6.1969) e e e e e e e e e e e s s e e e e e e e e 85 A5. A7. A8. A9. Post-experiment sud iometer earphone out put data for the right earphone of the hico HA-Zb audiometer for (1) the output measured for the pure-tone stimuli, and (2) the output measured for the unmodulated warble-tone stisuli center frequencies. The pure-tone seasurements were made according to the American National Standards Institute(ANSISB.6-1969) ................86 Pre-experimental harmonic distortion measure-ants of the fundamental for test frequencies used in the study. Measurements were made for the right earphone and right channel of the hiss ilk-2b audiometer under two conditions : (1) that for the pure-tones generated by tho hico ilk-2b and (2) that for tho unmodulated warble- tone center frequencies through the right channel and right earphone of the mica HA-Zh audiometer. leasure- ments were made in cospliance with the American National Standards Institute (ANSI 83.6-1969) . . . . . . 87 Post-experimental haraonic distortion measureaents of the fundamental for test frequencies used in the study. Measurements were made for the right earphone and right channel of the hico HA-zlt audiometer under two conditions: (1) that for tho pure-tones generated by tho noioo alt-2!. and (2) that for the unmodulated warble—tone center frequencies through the right channel and right earphone of the Bloc PIA-2h audiometer. Heasureaents were made in compliance with the Aaerioan National Standards Institute(AllSISB.6-1969)................ 88 Pre-and poet-experimental riseanddecaytisesas measured for pure-tones generated by the hiss llA-zlo audio-star. The times were measured from the right channel of the audiometer with the assistance of a storage oscilloscope. Measurements were ssde in compliance with the American National Standards Institute (ANSI 83e6'1969) e e e e e e e e e e e e e e e e e e e e e 89 Done-conduction calibration data recorded according to the noses specified by the Hearing Aid Industry Conference 2mm) Interia Bone-Conduction nu-ooholdo for Audiosetry Dybargsr. 1966) e e e e e e e e e e e e e e e e e e e e e 90 he- and post-experimental frequency checks of the test frequencies of the hico Ila-2b audioaeter performed in compliance with the American National Standards Institute (ANSI 83.6.1969). s e e e e e e e e e e e e e e e e e e e 91 vi A10. A11. A12. A13. All}. A15. A16. A17. A18. A19. A20. Bandosised presentation order (P0) for the various combinations of warble-tone frequency deviations (PD) and aodulation rates (HR) for subject #1 for test session “000......OOOOOOOOOOOOOOOOOOO hndomised presentation order (P0) for the various com- binations of warble-tone frequency deviations (PD) and modulation rates (HR) for subject #1 for test session #2 . Randomised presentation order (P0) for the various combin- ations of warble-tone frequency deviations (PD) and nodu- latios rates (HR) for subject #1 for test session #3 . . . Randomised presentation order (P0) for the various coabinations of warble-tone frequency deviations (PD) and modulation rates (HR) for subject #1 for test session“........................ hndomised presentation order (P0) for the various cabinet ions of warble-tone frequency deviations (PD) and modulation rates (HR) for subject #1 for test sessionfs........................ hndomised presentation order (po) for the various combinations of warble-tone frequency deviations (PD) and modulation rates (HR) for subject #1 for test ”Cimfléeeeeeeeeeeeeeeeeeeeeeeoe Randosised presentation order (P0) for the various cosbinat ions of warble-tone frequency deviations (FD) and modulation rates (HR) for subject #2 for test ”“1011“eeeeeeeeeeeeeeeeeeeeeeee Bandeaised presentation order (P0) for the various combinations or warble-tone frequency deviations (PD) and sodulaticn rates (HR) for subject :2 for test sessionfl........................ hndomised presentation order (PO) for the various ccmbinat ions of warble-tone frequency deviations (PD) and modulation rates (HR) for subject #2 for test session”........................ Bandoaised presentation order (P0) for the various cosbinations of warble-tone frequency deviations (m) and modulation rates (as) for subject #2 for testsessionm eeeeeseeeeeeeeeeeeeee hndoaised presentation order (P0) for the various combinations of warble-tone frequency deviations (PD) and nodulation rates (HR) for subject #2 for test '03'1on’5eeeeeeeseeeeeeeeeeeeeeee vii 93 95 96 97 98 99 100 101 102 A21. A22. A23. A2“. A25. A26. A27. A28. A29. Randomised presentation order (PO) for the various combinations of warble-tone frequency deviations (FD) and modulation rates (MB) for subject #2 for test 808.103 #6 e e e e e e e e e e e e e e e e e e e Randoaised presentation order (PO) for the various combinations of warble-tone frequency deviations (ED) and modulation rates (HR) for subdect #3 for t03t I..31°n #1 e e e e e«e e e e e e e e e e e e e e Randoaised presentation order (P0) for the various cosbinations of warble-tone frequency deviations (FD) and modulation rates (HR) for subject #3 for test 3"3103 #2 e e e e e e e e e e e e e e e e e e e e e e Randomised presentation order (P0) for the various combinations of warble-tone frequency deviations (FD) and modulation rates (HR) for subject #3 for test 3.3310n #3 e e o e e e e e e e e e e e e e e e e Randomised presentation order (PO) for tho various coabinations of warble-tone frequency deviations (PD) and nodulation rates (HR) for subject #3 for LOIL COIILOH #u e e e e e e e e e e e e e e e e e e e Randomised presentation order (P0 for the various combinations of warble-tone frequency deviations (FD) ind modulation rates (HR) for subject #3 for LOBL session ‘5 e e e e e e e e e e e e e e e e e e e Randomised presentation order (P0) for the various combinations of warble-tone frequency deviations (FD) and modulation rates (HR) for subject #3 for LOBL IOBILOD #6 e e e e e e e e e e e e e e e e e e e The mummy nsvm'lor: (FD) setting required on tho beat-frequency oscillator. along with the VOLT SCALE (V8) and OUTPUT VOLTAGE (V) on the function generator. and the Hs/DIV (H/D) setting of the storage scope spawn-analyser to produce and measure the warble- tone frequency deviations given" . . . . . . . . . . . The FRIEDIRCI’DRNIATION (FD) setting required on the beat-frequency oscillator. along with the VODT SCALE (vs) and OUTPUT VOLTAGE (v) on tho function generator. and the its/DIV (H/n) setting of tho storage scope spectrum analyser to produce and measure the warble- tone frequency COVL‘LIOBC 81'.n* e e e e e e e e e e e viii 103 100 105 106 10? 108 109 110 111 {fi'Al Pi II I A30. A31 . A32 . A33- A31}. A35- A36. A37- A38. The summer DEVIATION (FD) setting required on tho beat-frequency oscillator. along with the VOLT SCALE (vs) and OUTPUT VOLTAGE (v) on tho function generator. and the Hs/DIV (H/D) setting of the storage scope spectrum analyser to produce and measure the warble- tcn. mm?!” dOVutim 81”“* e e e e e e e e e e e The summer DEVIATION (1m) setting required on tho beat-frequency oscillator. along with the VOLT SCALE (V3) and ourpur VOLTAGE (V) on tho function generator. and the Hs/DIV (ll/D) setting of the storage scope spectrum analyser to produce and measure the warble- ton. “flame! dflutitm give!“ a e e e e e e e e e e The FREQUENCY DEVIATION (FD) setting required on the beat-frequency oscillator. along with the VOLT SCALE (vs) and ourpu'r VOLTAGE (v) on tho function generator. and the lie/DIV (H/D) setting of the storage scope spectrum analyser to produce and seasure the warble- tone frequency deviations givsn* . . . . . . . . . . . The FWUENCY DEVIATION (m) setting required on tho beat-frequency oscillator. along with the VOLT SCALE (vs) and ourpur VOLTAGE (v) on tho function generator. and the Its/DIV (H/D) setting of the storage scope spectrum analyser to produce and measure the warble- tene frequency deviations given‘ . . . . . . . . . . . Average (repeated aeasure) Rearing Threshold Level (an) and Sound Pressure Level (SPL) thresholds for each subject under each of the warble-tens combin- atiensferZSOHs eeeeeeeeeeeeeeeeee Average (repeated measure) Hearing Threshold level (an) and Sound Pressure level (SPL) thresholds for each subject under each of the warble-tone combimtionsforSOOHs eeeeeeeeeeeeeee Average (repeated measure) Rearing Threshold level (HTL) and Sound Pressure Isvol (SPL) thresholds for each subject under each of the warble-tone oombinationsforlOOOHs............... Average (repeated seasure) Rearing Threshold Level (HTL) and Sound Pressure Level (SPL) thresholds for each subject under each of the warble-tone oubinationsforzooons .,. . . . . . . . . . . . . . Average (repeated measure) Rearing Threshold Level (RTL) and Sound Pressure Level (SPL) thresholds for each subject under each of the warble-tone combin- ‘tiOu'formH'eeeeeeeeeeeeeeeeee ix 112 113 11k 115 116 117 118 119 120 A39. m0. AM o A02. M3 . M45. A50 . A51 . Average (repeated seasure) Hearing Threshold Level (HTL) and Sound Pressure Level (SPL) thresholds for each subject under each of the warble-tone coabinationsforBOOOHs................ Differences in dB of the warble-tone threshold from the pure-tone threshold for all subjects at each combination of frequency deviation and modulation rate. plus the averagedBdifferencefor25OIis. e e e e e e e e e e e Differences in dB of the warble-tone threshold hes the pure-tone threshold for all subjects at each combination of frequency deviation and modulation rate. plus the average dB difference for 500 as . . . . Differences in dB of the warble-tone threshold from the pure-tone threshold for all subjects at each combination of frequency deviation and modulation rate, plus the average dB difference for 1000 Rs . . . . Differences in dB of the warble-tone threshold from the pure-tone threshold for all subjects at each combination of frequency deviation and sodulation rate. plus the average dB difference for 2000 He . . . . Differences in dB of the warble-tone threshold from the pure-tens threshold for all subjects at each ccsbination of frequency deviation and modulation rate. plus the average dB difference for #000 Rs . . . . Differences in dB of the warble-tone threshold from the pure-tone threshold for all subjects at each combin- ation of frequency deviation and aodulation rate. plus the average dB difference for 8000 Rs . . . . . . . Ranks assigned to each subject for thirty warble- tonecombinationsatZSORs . . .. . . . . . . . . . . Ranks assigned to each subject for thirty warble- tonecombinationsatSOORs seeeeeeeeeeeee Ranks assigned to each subject for thirty warble- tonecombinationsathOOHs. e e e e e e e e e e e e e Ranks assigned to each subject for thirty warble- toneoombinationsatZOOOI-ls. e e e e e e e e e e e e e knits assigned to each subject for thirty warble- teneoembinationsatAtOOOHs. e e e e e e e e e e e e e Ranks assigned to each subject for thirty warble- tonecoabinationsat8000lls.............. 121 122 123 124 125 126 127 128 129 130 131 132 133 willfullllllllll... . .r -- L’I‘Ill‘l‘lllslil\[’ll‘ll\r All, A! t ‘ ' ‘ b A e. .I o 0 ~ a s sf . o . I a s 0 s O I ' h t a , I I i C .e I . A O O Q a u e O o . 9 . I v s C C s O o C a s . A 9 s . O I U n. a e. v v .s p Q 3 I. 0 u . a - I I a s . . 7 O C o. . r s a t . a I v. ' | l v s e. s Q D V s t a . . LIST OF FIGUBm 1 . Block diagram of test environment showing equipment used e e e e e e e e e e e e e e e e e e e e e e e e 2 . Block diagram of the beat-frequency oscillator (Bruel a Kjaer, Hodel 1013) with eaphasis on its sections utilised in the generation and control of th. "rbIC‘ton. e e e e e e e e e e e e e e e e e e 3. Mean sonaural pure-tone air-conduction thresholds for the three subjects used in the experilent. These averages are based on five tests employing descending 2 dB steps of attenuation . . . . . . . . 5b- 6a. 6b. 7a. lean dB difference scores for each warble-tone frequency deviation with modulation rate as the paraseter Mean dB difference scores for each warble-tone aodulation rate with frequency deviation as the parameter lean dB difference scores for each warble-tone frequency deviation with modulation rate as the parameter Mean dB difference scores for each warble-tone modulation rate with frequency deviation as the parameter nean dB difference. scores for each warble-tone frequency deviation with modulation rate as the paraaeter lean dB difference scores for each warble-tone modulation rate with frequency deviation as the paraseter Roan dB difference scores for each warble-tone frequency deviation with modulation rate as the parameter x1 38 38 39 39 1:1 7b. 8a. 8b. 9b. 10. 11. 12. 13. 1“. Mean dB difference scores for each warble-tone modulation rate with frequency deviation as the P‘r‘-.t9r e e e e s e e e e e e e e e e e e e e e e Roan dB difference scores for each warble-tone frequency deviation with sodulation rate as the parameter s e e e e e e e e e e e e e e e e e e e e lean dB difference scores for each warble-tone modulation rate with frequency deviation as the I‘ll-CLO! e e e e e e e e e e e e e o e e e e e e e Hun dB difference scores for each warble-tone frequency deviation with modulation rate as the p‘r‘latCr e e e e e e e e e e e e o e e e e e e e s lean dB difference scores for each warble-tone modulation rate with frequency deviation as the P‘IIIOLOI e e e e e e e e e s e e e e e e e e e e a lean differences in dB between warble-tone and pure-tone thresholds for the warble-tone combin- ‘tiOflB indicated in O‘Ch graph e e e e e e e e e e e Roan differences in dB between warble-tone and pure-tone thresholds for the warble-tone cosbin- ationsindicatedineachgraph . . . . . . . . . . . lean differences in dB between warble-tone threshold and pure-tone threshold for the warble-t one combinations indicated ineach graph . . . . . . . . Roan dB difference scores for each warble-tone combination utilised at 250. 500, and 1000 Rs as a function of the modulation index. Hequency deviation 13 thO parameter s e e e e e e e e e e e e Bean dB difference scores for each warble-tone combination utilised at 2000. #000, and 8000 [is as a function of the modulation index. Frequency deviationisthepsraaeter... .. . .. .. ... Visual display on an oscilloscope produced by a spectrus analyser showing a 110% frequency deviation centeredaroundabasefrequencyoinOOHs . . . . Visual display on an oscilloscope produced by a spectrum analyser showing a 110% frequency deviation centered around a base frequency of 8000 Rs . . . . xii 1&1 #2 1+2 “3 43 “9 50 51 59 60 it? 1" .[fl't'l’llllsl‘t’ . ‘ . h v a s h I 9 v s ' l e . O O . . O s I O C . I C ‘ e. v 0 O l e I V . O O C . e t I C s C I O O . O O r e . i e e I . t . . O O _ C. D . n I Q . . e y s.- s. a I . e a or . r A \ s A f . . s s I . I O l \- . O s s . A. B. C. D. E. I". Go H. I. J. K. L. LIST 01" APPIIDICES “bl“tNOHCDVOhmrutRMeseeeeeeee Rationale and Procedures for Calibration of the ”DID-T010315“). eeeeeeeeeeeeeeeeo Linearity of mice luv-25 Audiometer Attenuator . . . hrphoneOutputlhta ................ lhrmcnicDistortionIhta .............. Rise and Decay Time ate for Audiometer Interrupter . Bone—Conduction (hlibration Data . . . . . . . . . . TestFrequencyClecks................ Randomised Presentation Order for warble-Tone “MiGOIOOOOOOOOOOOOOOOOCOO. Frequency Deviations for hob Test frequency (In Both Porcent and Rs) Along Vith Readings Required 0: the Instrusentat ion Utilised to Produce and Measure the Iarble-ToneStimuli................. Average Rearing Threshold Level and Sound Pressure Level Thresholds for hch Subject mder fish of the Barbie-Tone Combinations for bch hequency . . . . . Individual Subject and lean dB Difference Scores for hch Herbie-Tone Combination and Frequency . . . . . inks Assigned to fish Subject for hch Varble-T‘one Combination for Kendall's Coefficient of Concordance xiii 78 85 87 89 90 110 116 123 129 CHAPTER I INTRODUCTION Early identification and management of hearing loss is of para-cunt isportance if a young child's speech and language are to develop ade- quately. Enact knowledge of the function of the auditory system is necessary for planning a training program for those with cosmunioative disorders due to a hearing problem. The neonatal auditory test procedures described by Vedenberg (i 956). Hardy. Dougherty and nsrdy (1959). Downs and Storritt (1967). and Schulman and Fontana (1969). as well as many others have proven helpful in the early identification of deafness in infants. Likewise, screening tests described by Johnston (19%. 1952). Roger and Newby (1907). Gardner (191:7). noyorson (1956). Nielsen (1952). Vobotor (1952). Glorig (i953), Glorig and Vilko (1952) and others have provided useful infor- mation for an age range fros childhood through adulthood. However. from the audiologioal and educational point of viov. sany methods used to test the hearing of young children (screening and/or threshold) do not pro- vide sufficient information concerning the child 's threshold sensitivity. In fact. tho period froo birth up to 24} or 3 years of ago, before conditioned-play audiometry can be used (hrr. 1955: Hillis and Oyer. 1960). has remained baffling with regard to threshold audiometry. At- tempts have been made to obtain behavioral responses with a variety of stimuli. including bells. the human voice. pure-tones. gongs, claekers. oral instructions. household sounds, white noise. bussers. etc. A dif- ficulty with the presentations of the majority of these test stimuli is that the frequency and intensity characteristics are not consistent or controllable . In addit ion, it is important to have inforeat ion about hearing threshold levels as a function of frequency. However. young children frequently refuse to wear earphones for pure-tone threshold aeasurements. To circumvent this probles. a number of individuals have suggested the use of pure-tones in a sound-field condition (DiCarlo and Bradley. 1961: Bender. 1967: andSmith. 1969). Hhile testing in a sound-field cannot yield results as precise as those under earphones , this method can provide useful information about a child's hearing that often may not be obtained in any other way. However. if one introduces pure-tones into a sound-field. reflections free the boundaries of the test recs say result in standing waves. As a result. sons of the sounds will be reinforced and others cancelled as the subject shifts position within the room. The frequencies which are affected will depend upon the acoustical characteristics of the particular test room, and the reflections are a sore serious problea in some rooss than in others. This problem can be resolved satisfactorily by the use of a frequency- modulated signal (warble-tone). Since its introduction into hearing testing. the warble-tone stim- ulus has been advocated for clinical use as a aethod of threshold test- ing. especially for children (Reilly. 1958a. 1958b: Allison Laboratories, Inc.. Bulletin A-fi: Langenbeck. 1965: Miller and Poliear. 19615: lhrdy. 1958: Heron and Jacobs, 1968, 19698 Killer and hbinowits, 1969: Liden Kankkunen. 1969: Puck. 1970). Likewise. some commercial neonatal test- ing devices eaploy a narrow band noise produced by frequency aodulation for infant hearing screening. further. personal coemunication with a number of audiole suggests that warble-tone is becoming a popular stisulus for threshold measure-wt . hrble-Tone As An Auditgg Stimulus Vsrble-toae is produced by frequency modulation . Frequency aodu- lation refers to a periodic modification of a base or center frequency. with a variation of this base frequency to values either above. below, or around it with amplitude held constant. The warble-tone varies as a function of three basic paraseters: (1) the center or base frequency. (2) the frequency deviation (FD), and (3) tho modulation rats (an). The center or base frequency is the frequency around which the modulation or frequency change takes place. The frequency deviation (range of percent of frequency change or actual variation in Rs of frequency change) is explained as follows: If the bsso frequency is 1000 Rs, then a plus and minus (i) 5% frequency dovi- ation around the base frequency would produce a variation in the 1000 Rs tonefromalewof950flstoanuppsrfrequencyof1050Rsora1'50Rs change. As this signal is repeated. the warbling sensation results. For a tone that warbles above the base frequency, the change for a plus (4-) 5% range would be from 1000 Rs to 1050 its for a 1000 Ha lass frequency or a +50 Rs change. Thus. a 1:51 change is an actual nosinal 10% frequency change. whereas a +51 is a nominal 51 change. The aodulation rate (rate of frequency change) refers to the number of tises per second that the frequency varies (warbles) froe one extreme to the other of the frequency liaits. A modulation rate of 3 per second for a frequency deviation of «06$ for a 1000 Rs base frequency would mean that the tone would change in frequency free 1000 as to 1050 as three times a second. Hhrble-tone is currently included as an accessory stimulus by some sanufacturers of clinical audioseters. Although little has been written about the status of warble-tone in audio-store. Staabrand Rintelmann (1971) conducted a survey aacng sanufaeturers in nine countries to ascertain the current status of warble-tone with respect to tho various warble-tone characteristics available on commercial audio-store. Con- cerning the warble-tone signal itself. replies of respondents to the questionnaire indicated that the frequency deviation varied from approx- imately +0.2fliabove the base frequency to as high as tiofliareund the base frequency. The sodulation.rates ranged free 2 per second to as high as 10 per second. Audiometer manufacturers accoaplished the warble- tone in essentially two different ways. either by modulating around the base frequency or above the base frequency. with the waveform of the warbled signal either sinusoidal or rectangular. The signals were not calibrated to any single accepted. current standard. 0! those manufac- turers of audiometers who did not offer the warble-tone as a stimulus. thoir primary reason was that tho warble-tome's significance had not been determined adequately and that there had been little or no demand for it as an auditory stimulus. Staab and Rintelmsnn (1971) concluded: . . . there is a dearth of infer-ation concerning the most appropriate warble-tone stimulus parameters to be employed in threshold determination. This problem must be resolved before warble-tone audiometry can seriously he considered as part of the audiologist's clinical armamentarium (Unpublished). In addition. no studies have systesatioally explored the comparison between warble-tone thresholds and thresholds obtained by conventional. pure-tone audiometry. Since the warble-tone stimulus characteristics (frequency deviation. aodulation rate. and wavefors) are variable aaong cosmercial audiometers. differences in threshold might be expected simply as a function of the variety of stilulus parameters employed. Statement of Mes has the review of literature it is obvious that infer-at ion con- cerning the appropriate stimulus parascters with respect to the nodula- tion rates and frequency deviations used for warble-tone audiometry is lacking. The specific questions which should be answered are: 1 . How do warble-tone thresholds esploying various combinations of nodulation rates and frequency deviations compare with each other and with conventional pure-tone thresholds? 2. How do warble-tone thresholds (with respect to frequency deviation and sodulation rate) vary as a function of frequency? 3. hot is the interaction of frequency deviation with modulation rate? 1.. Vhot is tho relation aaong the threshold rankings of tho various warble-tone combinations by the subjects? 5. llhat are the effects of the nodulation index (the ratio of frequency deviation to modulation rate) on warble-tone thresholds? CHAPTER II ERIN OF THE LITEATURE The fellcwing discussion presents a review of the literature rele- vant to this investigation. The review includes: (1) studies suggesting warble-tone for threshold determination. (2) literature concerned with oooporisoos (diroct and/or indiroct) of tho warble-tone threshold and conventional pure-tone thresholds. and (3) investigations of warble- tone stimulus parameters that are currently being used on cosmercially- available audioneters. Vhrble-Tone for Threshold Detersination The warble-tone stimulus is currently being used and has been evaluated by a number of individuals for neonatal hearing testing (hondol. 1968: Beadle and Crowoll. 1962: Horse and Jacobs. 1968. 1969: Peck. 1970). However. it aust be realised that when used for neonatal testing. the response that one intends to obtain is that of a behavioral response to a suprathreshold stimulus and not a threshold level measure- sent. At least seas of the “warble-tones“ created by neonatal hearing testing devices give the subjective listening impression of being narrow bands of noise rather than that of a frequency modulating signal. This is due to the generation of the stimulus signal with frequency deviations around plus and minus (i) 150 [is and modulation rates of 30 to so por second (Phonic Ear and the Rudaose RA-109 Vhrblet 3000). Stevens and novis (1938) have indicated that when the modulation rate increases to as high as 12 per second one begins to experience a group of tones rather than a single aodulating tone. Because of this. and because of the fact that they are not intended for threshold deteraiaation (due to the high sound pressure level tones generated to elicit behavioral responses). no further mention will be made of the neonatal testing devices unless they have been advocated for threshold determinat ion at some later developental age of the infant. As a measureaent of behavioral response to warble-tone stimuli. Ruising in 1953 (oitod in Jerger. 1963) reported tho moving of a block as the conditioned response with children between 30 months and 7 years of age. This sound-field conditioning procedure was used as an intro- ductory test to threshold seasuresent (which involved pure-tones deliv- orod through earphones). Reilly (i958a) who was influenced by the work of Ruising developed an instrusent for sound-field testing ef children. Based on Ruising's apparatus. it used warble-tone for the clinical determinat ion of three- hold. This instrument. the “Audie—l'requency Vobbulator. " allowed for output to two sets of speakers: one set portable and the other set fired to the arms of a chair on which the subject was seated. Reilly suggested that testing with warble-tone could begin at 6 months of age but tint the possibility at ”play” audiosetry occurred with the 21 to 33 month age group. Glildren 33 scnths and older were introduced to warble-tone while playing at a table. and. as their faailiarity with the test signal increased were taken to the test chair. Audiograas were then obtained by means of play audiosetric techniques using warble-tone introduced through the speakers at fixed distances from the child's head. Pure-tones were later substituted for the warble-tone and audiegrass again obtained. Finally. the child we introduced to the headphones . With the experiences the child has had fron the sound-field testing conditions he will toler- ate the earphones mere easily and at a younger age. As a result. pure- tone audiegrass can be recorded much earlier than usually is the case. Beilly cemnented that the youngest child froa whom he had been able to obtain a warble-tone audiegram was Just under 2 years of age. Again. in a panel discussion on "lhe Assessaeut of Auditory Function: 1. Hearing in mildren." Reilly (1958b) stated that he had been using frequency modulation in testing babies and young children. and that during a six nenth period had good success with this nethod. He wondered why this had not been discussed by the panel when speaking about succesmtl techniques used with children. In response Hardy (1958) commented that they had used frequency aedulat ion for six or seven years as part of the pure-tone battery in testing. He felt that it was a good attention centering device and that responses were seaetises obtained that could not ordinarily be elicited. especially with children having nervous systea involvement . liller and Pelisar (19615) in a textbook concerning the audiological evaluation of the pediatric patient . wrote that . . . ”Frequency modula- tien is an effective way of breaking up standing wave patterns and should be utilised whenever pure tone testing is performed in a sound now- (1). 30). They stated that both sound-field pure-tone threshold measurements and sound-field hearing aid evaluations could be better acconplished with the use of warble-tone. In still another textbook. Langenbeck (1965) stated that 11' the audioaeter has a provision for the continuous alterat ion of frequency with intensity Iaintained constant. that it should be utilised to help determine the threshold curve. He further wrote that with respect to children. especially those fres about 5 to 7 years of age. the tester canbejustassuccessfulashe iswithadultsifhecanmake ‘thegame" a little sore interesting for the child. the technique that can be used is to seve the frequency dial up and down. which results in 'webbling' of tones with changes in pitch. This adds a seaewhat fluid character to the audioaetric signal which maintains the child's attention. By contrast . it should be noted that none of the three most commonly- used textbooks for the introductory study to audiology in the united States have a single reference to the assescsent of hearing thresholds in children with a warble-tone stinulus (Rewby. 196a; O'Neill and Dyer. 1966: novi- and Silver-an. 1970). Miller and habinewits (1969) performed con (conditioned orienting reflex audio-etry) on 183 ‘children as part of a couplets audiological evaluation. The stimuli used were pure-tones in the 250-4000 Ha range Requency-sedulatod by 5% of the basic frequency. 'Ihe children tested were in two subgroups of a rubella pepulat ions those with hearing impairments only. and these with hearing impairment plus one or sore associated probleas. The technique was successful with 76 of the 183 children tested. They reported: ”COR and sound field audionetry are used only on children who cannot respond to conventional audienctric testing with earphones and a bone conduction vihrator' (p. 95). Liden and lankkunea (1969) reported on a visual reinforcement audiosetric technique in the testing of young deaf children which utilised the warble-tone. 'lhe apparatus was primarily designed for neasuring the monaural sound-field thresholds for warble-tones. For 10 visual reinforce-out they used slides projected on a frosted glass window located on each side of a curved front panel of a box-shaped apparatus. mey began with a 500 Rs warble-tone presented to the right loudspeaker at 30-40 dB above the estimated threshold. and iamediately followed this with a picture on the right window. The visual reinforce- ment was intended to aka the rather meaningless pure-tones more interesting to the children. Dy gradually reducing the intensity and watching the response of the child. it was possible to obtain a pure- tone threshold. By the lid 1950's manufacturers of audioseters began to advocate the use of warble-tone for threshold determinat ion and other purposes . Allison laboratories. Inc. Bulletin 9:1 (not dated) sent a questionnaire on "The Use of Warble 'rone" to a group of users (nunber in group not indicated) of their equip-ant which had the warble-tone feature avail- able. 0: these that replied. more than 85% indicated that tho wnrble- tone was used for threshold measurenent either through the earphones or loudspeaker. Allison laboratories reported surprise in the large porcentags using warble-tone for threshold measurements. Here specif- ically. advantages were given by respondents for warble-tone with children. the elderly. and for these with tinnitus. Other uses of the warble-tone included in the questionnaire responses were a masking for pure-tones. seasurements through the loudspeaker of hearing aid frequency response. seasurenents through the loudspeaker of hearing aid gain. and difference linen frequency tests . In a 1963 manual on operating instructions for their warble-tone adapter. the Beltene Electronics Corporation suggested the use of warble-tone in cases of tinnitus. sound-fieId pure-tone testing. and 11 for frequency difference linen. Carver (1965) in a booklet entitled Instrumentation. also suggested that warble-tone be used for cases with tinnitus. However. he did not discuss its use for frequency difference linen. He did add that the warble-tone in,a sound-field allows for aided and unaided threshold seasurenents and was advantageous when measuring thresholds of children because it holds their attention longer than pure-tones. hadsen liectrenics' operating manual for their clinical audiometer (Nodal 0R.60) with the warble-tone stisulus makes no aention of the warble-tone being used for threshold neasurement. Instead. they recom- mend its use for a difference linen for frequency (DLP) test. Tracer. manufacturer of the Allison Model 22 Clinical and Research Audicaetar. states that the warble-tone is an excellent stimulus for use where tinnitus is present. It also serves as an effective sacking signal for pure-tones and as a sound-field signal for these who cannot be tested with earphones (Ti-om Specification Sheet for the Allison hodol 22 Audiometer). In correspondence with the Rice Company of Japan. manufacturers of audio-stars. the following statesent was made with respect to the warble-tone stisulus: “This can be used to decide threshold value for kindergarten children within a short tine. It can be applied for mentally retarded persons also” (personal correspondence. 1970). In a questionnaire survey by Stash and Rdntelaann (1971) to manu- facturars of’audienetcrs in nine countries. of these who included warble-tone as an auditory stisulus. the most often suggested use was for threshold measureaent in sound-field or under earphones. However. 12 only two of six manufacturers reported that they had published instruc- tions on its use for threshold measurement. Goapggison of Harble-Tone and Conventional Pure-Tone Thresholds The literature review included in this section is taken free studies indirectly rather than directly related to these two types of stimulus thresholds. no study has been located in the literature which has systesatically made this eesparison. In 1933. Sivian.and Hhite utilised the warble-tone with the psycho- physioal method of limits to deteraine the upper portion of the aonanral. miniaal audible field (MA?) thresholds for 0° incidence on 1br9normal' listeners (Sivian and inlite. 1933). The reasons given for using the warhle-tone were ”. . . psychological. in that it reduces fatigue and uncertainty on the part of the observers and physical. because of snoothing out of the residual standing wawe patterns produced by reflec- ticns' (p. 290). They used a constant modulation rate of 10 per second and a frequency deviation which was progressively reduced in percent free approximately 24.6% at 1100 Hz (:50 lie) to approxinately 10.97% at 15,000 Hz (iiho Rs). They reported that a few check neasurenents made on the case individual with the warble- and pure-tone indicated no systesatic differences between the threshold values in the two stimulus situations other than those due to the physical and psycholog- ieal considerations the warble-tone was intended to mini-inc. Binaural HAP threshold measure-ants performed the same way and also done without a “warble” tone resulted in siailar results to those in the aonaural HAP condition. These measure-cuts were all made at a distance of one meter in front of a loudspeaker in a highly absorbing acoustic structure which they called the “sound stage.“ 13 Iebster (1952) reported on a recorded. pulsed-tone group hearing test which used warble-tones with a modulation rate of 5 per second and an unspecified frequency deviation. The test was given to 200 college students in both a sound-field cendit ion in a reverberant recs and under earphones. lheu eoapared with two other control group hearing tests [one consisting of recorded warble—tones through headsets and the other a pure-tone pulse test described by layers at al.. (1948)] . this test was as reliable as the better of the two control tests whether heard over earphones or loudspeakers. He concluded that as a screening device this test was satisfactory. Webster also indicated that ”Enough infer- matien is available so that the headset levels could have been pro-set to read directly in 'hearing loss' values" (p. 217). here recently. Reilly (1958a) used an instrunent for sound-field testing of children called an Audio-Frequency Webbulater based on one used by Raising in The Netherlands for the clinical determination of threshold by warble-tone . Both the modulation rate and the frequency deviation were variable. the former unspecified and the latter from to to 2100 Rs. he also mentioned (but presented no data). that: Ry using pure-tone sounds in the speakers instead of the warbling tone it is easily demonstrated that a child will respond to a warbling tone of such loss intensit than to a pure-tone of the same frequency (1958a. p. 365 . In two recent articles (mllos and Till-an. 1966: Young and Ehrbert. 1970) sons effects of the sodulation index (the ratio of frequency deviation to modulation rate) was sampled by Rekesy tracings but not systematically explored. Both studies specifically looked at threshold ehanges in abnormally adapting ears but also included cone linited data concerning noraal listeners. thz (19. the 1“ Dallas and Tillman (1966) used four different .aodulation rates (1. 2.5. 10. and 25 per second) and three different frequency deviations (10. 63. and 250 Re which were 11. approxisately i6. and 125% respec- tively) at 500 R3 with one normal hearing subject (one ear). The results showed that in general. the hearing sensitivity threshold iaproved slightly with increasing frequency deviation. and that con- sistently better thresholds were obtained with slower repetition rates. They suggested. however. that it is the modulation index (ratio of frequency deviation to modulation rate) which might be the critical variable in determining threshold sensitivity. and that under this condition better thresholds are obtained with saaller frequency deviation. Young and Herbert (1970) utilised four noraal. trained listeners (four ears) and aedulation rates of 1. a. 10. and 25 pcr second and frequency deviations of 110. 163. and 1250 RB. Threshold values obtained by fixed frequency Rakesy audiometry at 1000 Rs showed that the thresholds resained about the case or iaproved slightly with increasing frequency deviation. As the modulation increased for a given frequency deviation. the threshold becase poorer. The greatest dB change between the coabinations of frequency deviation.and nodulation rate was 7.1 dB. with respect to the modulation index. however. Young and Harbert tend to confira Dalles and Tillnan's observation that better thresholds are obtained with caller frequency deviation. In an investigation of warble-tones with very young children. Peck (1970) need a frequency deviation of 5% to determine auditory thresholds. Rb reported that it was difficult to give a precise reference level for the warbled sound-field pure-tones. but that the results were assused de for Til 3th atic 15 to approach the ISO-1964 sero reference levels. He did not specify the aodulation rate used. while not related specifically to threshold. in a study of respir- atory curve responses of the neonate to auditory stisulaticn. Heron and Jacobs (1968) found that of a variety of test tones. warble-tone pro- duced the most consistent response. In 1969 they had a warble-tone audioneter built to their specifications which had three frequency ranges: 250-500. 1000-2000. and 11000-8000 Re. In each of these ranges it was possible to modulate the frequency up to t1/3 of the center frequency. The modulation rate could be altered free 1 to 10 per second in gated steps. After many trials they found that the following settings were the most effective: 1. Low frequency. Full sodulation for 1! seconds at a modulation rate of 10 per second. 2. Hiddle frequency range. Full modulation for 4 seconds with a aodulation rate of 6 per second. 3. High frequency range. lull nodulation for 1} seconds with a modula- tion rate of 1+ per second. It is obvious free the afcrucntioned studies that none were designed to systenatically investigate the threshold levels obtained for different center frequencies with varying cosbinat ions of modulat ion rates and frequency deviations. Still. the results of mllos and Tillman (1966) and Young and Herbert (1970) suggest that the warble-tone stisulus parameters (pertaining to modulation rate and frequency devi- ation) do have an effect on hearing threshold levels. 16 Iarble-T‘ong Stimulus Parameters Currently Used There is a dearth of published information concerning the warble- tone stimulus parameters currently being used. Because they suspected that the stimulus paraaeters varied considerably by manufacturer. Staab and Rintelmann (1971) conducted a survey to determine the current status of warble-tone in audieaetcrs. Of twenty-nine audiencter manufacturers. twenty-four replied (82.7”. representing nine different countries. Nine aanufacturers indicated that they already eaploy or are planning to include warble-tone on their audieaetcrs in the near future. or eight manufacturers (33.3%) that provided information relative to the stisulus paraaeters. the following information was obtained: (1) frequency deviation varied from approxinately +0.2X above the base frequency to as high as 110% around the base frequency. (2) aedulation rate ranged free 2 per second to as high as 10 per second. (3) audio-eter manufac- turers accomplished the warble-tone in essentially two different ways : either by modulating around the base frequency or above the base fre- quency. (it) the waveform of the warbled signal was either sinusoidal or rectangular. and (5) the signal was not calibrated to any single accepted. current standard. Hith respect to the frequency deviation and the modulation rate. the consensus of the respondents was that the bases for the para-eters currently being used had not been adequately substantiated by published research. Aside from the study Just cited. no infer-ation has been located which directs attention to the stimulus paranoters being used in con- mercial audioseters. fir 1? §u_-_-__arz While soae individuals have advocated the use of the warble-tone stimulus for threshold detersination. especially for young children. little infer-ation is available relative to the appropriate stisulus para-stars. Systesatic investigation of various frequency deviation and nodulation rate conbinaticns should be perforaed to determine which conbination(s) give threshold levels that most closely approximate those obtained by conventional pure-tone audiosetry. Although one of the major applications of warble-tone audiometry is intended for testing young children. a careful study of the ispertant stisulus paranoters should first be accoaplished with experienced adult normal listeners. It is the purpose of this study to obtain such data. Thereafter. in order to obtain normative data which can be applied clinically. sub- sequent studics can be conducted on a limited number of stimulus paranotcr coabinations on a large sasple of children and adults. After such investigations have been conpleted. warble-tone audionetry can be meaningfully eaployed as part of the audiologist's clinical areasantarium. CHAPTER III murmur. mocmuam Inforsation concerning the selection of subjects. instruaentatien. asbient noise levels. calibration. stimuli enployed. and the experimen- tal procedures utilised are included in this chapter. Briefly. three normal-hearing experienced listeners were individually adninistered thirty cosbinations (sixty repeated measureaents) of frequency devia- tions and modulation rates for each of six frequencies at octave interb vale free 250 through 8000 He. The warble-tone thresholds obtained were then oospared with the case subject's conventional. pure-tone air- conduction thresholds at the same test frequencies and for the sane ear. Sub s Three noraal-hearing adult feaales. ages 22. 25. and 30 served as participants in the study. Since the study was primarily designed to coapare each individual's conventional. pure-tone airbconduetion thres- holds with his warble-tone thresholds. three subjects were considered to be adequate. The subjects were selected on the basis of the following criteriat 1. no previous history of ear pathology. 2. no constant or disturbing tinnitus. 3. no family history of hearing impairment due to possible hereditary 18 19 h. Hearing at least at 15 dB re ANSI-49691 reference thresholds for octave frequencies free 250 Rs through 8000 He in the test car and with no air-bone gap. 5. Hust have undergone at least ten pure-tone air-conduction threshold audiograms (criterion for experienced listeners). Instrunentatien All equipment enployed during testing. with the exception of the earphones. subject response button. bone vibrator. and calibration equipment was located in the control room of the test suite used in this study. The equipaent aentioned (except the instruaents necessary for air- and bone-conduction calibration) was located in the adjoining subject test recs. Figure 1 provides a scheaatic diagras of the equip- ment used during testing. nice PIA-24 Audiometer. The hico Model “-20 audio-eter is a dual- channel instrument which allows for testing 11 frequencies from 125 through 8000 Ha and also has a Hearing Threshold level range of from -25 dB to 110 dB re ANSI-1969. This audio-eter was utilized in obtain- ing the pure-tone air-conduction. bone-conduction. and warble-tone threshold aeasurements in 2 dB steps of attenuation. OscillosceE and Spgctrum Analyzer. The Type 561+B Tektronix Storage Oscilloscope with Auto Erase is designed to store cathode-ray tube displays for viewing or photographing up to an hour after application of the input signal. In addition. the instruaent can be operated as a 1American National Standards Institute (ANSI) ”Specifications for Audie-stern” 83.6-1969. .eces anelfisue seasons eseasowuose sees me seems: «scan .a one»: (mex\/ R I: 20 .A/ L Sn 1 Hounds—2 cones: econ rune: Seesaw nope-ode: a“ acacia g]: I one“ 3.3 v5.3 nova—co oedema—ear hone-cg scorn schooner oooqpnm eUIII. Jxlllwpr «Re a m .8 « INN"! moan II! can nose-fies «Newsweek-bu zoom zen—”Hing zoom ACE—.200 21 conventional oscilloscope and was used this way to measure the stimuli rise and decay times. The oscilloscope is ccapatible with Tektronix plug-in units and a Spectrua Analyser Hodel 3L5 was utilised to measure the warble-tone frequency deviations desired. Function Generator. The Hewlett-Phckard Hedel 3310A Function Generator is a voltage-controlled generator which allows for low distortion and high stability sine wave generation over a frequency range of 0.0005 Ha to 5 HHs in 10 decade ranges. The frequency of the sine wave generation detersined 'the: nodulation rates and its output voltage was. instrunental in obtaining the desired frequency deviation. Voltmeter. A Bruel a Kjaer Type 2009 Electronic Voltseter allowed for fine adjust-ants of the output voltage of the function generator. This voltaeter is a vacuun tube voltmeter for AC measurements in the frequency range free 2 H! to 200.000 as. Eleven voltage ranges are present allowing for full-scale deflection free 10 millivolts to 1000 volts. Eggguengz Counter. The Bekman iput and Tiler. Hedel 6108 is a 100 ans unit which can measure frequency. time interval. period. multiple period. ratio. multiple ratio. and which counts randcs events. It has a stabil- ity of better than :3 parts in 109 per day. Visual measurements are presented in an eight-digit. inline. nunerical display utilising glow tubes. The display includes an autosatieally-pesitioned decinal point and an indication of units of measureaent. This was used initially to determine the accuracy of the frequency of the modulation rates and then during the experiment to monitor the base or center frequencies of the test stinuli. hr- 22 Beat-Frequency Oscillator. A Bruel and Kjaer (Bax) Beat-Frequency Oscillator Model 1013 was used as the aain source for the generation of the warble-tones. This is designed for seasurenents in the frequency range ZOO-200.000 Hz and consists of an oscillator. mixer. and an anplifier section. It works on the heterodyne principle using two high-frequency oscillators. one of which operates on a fixed frequency. while the frequency of the other can be varied by scans of a variable capacitor. The required signal base frequency is obtained as the difb ferencc between the two high frequencies and can be read off a large illuainated scale. the pointer of which is connected to the variable capacitor. The oscillator also allows for frequency modulation of the output signal. Figure 2 shows a block diagraa of the oscillator and the sections utilised in the generation and control of the warble-tone. The fixed oscillator is tuned to 1.2 MHz and can be externally frequency aodulated by means of a more CORT‘ROIJZ and reactancc tube circuit. The latter acts as a variable inductance and the nodulation swing (frequency deviation which is controlled by the anplitudc of the oscillations) for this experiment was continuously varied free 0 to £9000 us. This was aocoaplished by means of a potentiometer on the front panel of the apparatus marked FRIQUIICY BRVINTIOh’and also by the output voltage of the external function generator. A variable capacitor inserted in the tuned circuit of the fixed oscillator and operated by the knob aarked FRIQDIICI IRCRIIIIT. pernits exact frequency selection in the range 2Horde in capital letters in this thesis relate to controls (dials) on the equip-cut utilised in the experiment. 3 2 .csovneapuss 23 mo Honvnco use scavenge» one 5 dead—"...: esofloee a: no 33E... 3:. A93 Hoes. £32 a fleshy 83323 kaoagufiop 2.» no loose «83 .N 86: _ 382.8 _ eve-ems _ In: 0. «IN. d .08 33> . _ _ _ rifle . Hops—533.. _ 3ch .J 3350 £53.35 II. p.338 32. 839833 1 never _ neg segues _ _ _ _ .838 . 33. _ 39930 933.35 .97... an: N. « VLI. .5»! :5 Fl, rats lul .85: II 38> ll. .25 .nfl cl _ A0929... sou—”Baa". 21+ 2300 Ha in relation to the setting on the main scale. The frequency accuracy of the incremental scale is 1'5 Ha and that for the aain scale is 11 1‘10 as. For external frequency modulation. an external generator (Hewlett- Packard Model 3310A Function Generator) was used to allow for sinusoidal frequency deviation changes. to allow for scse variation of the range of frequency deviations. and to obtain modulation rates not allowed directly by the beat-frequency oscillator. This function generator was connected to two terminals of the Jack of the front plate marked arms CONTROL. For external nodulation it was necessary to connect the external generator between teninals f and b of the RBIOTE comm. and have the IODULATION WONG! switch set to "Ext. Hod.” The impedance of the external generator had to be low (approxintely 1 kohm). The voltage developed across the grid circuit of the variable oscillator is fed to the sixer tube via a buffer asplifier stage. This stage. which prevents undesired coupling between the fixed and variable oscillator. also increases the signal level to a value required for correct functioning of the mixer. The LOAD was connected to the INPUT of the storage oscilloscope and related spectrun analyser for measureaent of the frequency deviation in Ha and also to the Ac INPUT of the counter to monitor the warble- tone's base frequency. The HATOHIIIG MANOR of the beat-frequency oscilJator was turned to “Attenuator” and the A‘I'I‘HUATOR OUTPUT was set to #00 nillivolts and led to the hiss ill-23 audio-star through its ACCESSORY INPUT. (This voltage was adequate to develop enough output at the earphones to allow for a ”0" VI) reading at all test frequencies.) 25 W Subjects were tested in an Industrial Acoustics Corporation (no) Series 1600-Acr sound-treated rocs cosbination consisting of a boo Series control room and a 1200 Series test booth. All threshold testing was presented monaurally via the right earphone (Telephcnics TDH-39/1OZ) aounted in a Ill-#1 /AB cushion. The nontest ear was covered by the left earphone as would occur in renal testing conditions. The subject was seated alone in the test recs and the najsrity of the equip-eat (except earphones. bone vibrator. and response button) was located in an adja- cent centrol roos. Ambient Noise Levels in Test Room The ambient noise levels of the test roos were seasured in accord- ance with the criteria set forth by the American Standards Association for 'hckground Noise in Audicseter Noose“ (ASA 83.1-1969).3 The levels measured and the instruaentation involved in making these determinations are recorded in Appendix A. The levels recorded met the criteria set forth by the ASA and. thus. were sufficiently low so as not to interfere with threshold neasureaents . Calibration alibration of all test equipent took place at the beginning and at the end of the experiscnt. Specifically. the lhicc HA-Zh audioseter was calim-ated and/or checked for frequency at octave intervals fros 3Hhile the nane of the American Standards Association (ASA) is now the Aserioan National Standards Institute (ANSI). standards adopted prior to 1969 and the nase change will be specified in this paper according to their original description. 26 250 through 8000 an, linearity of attenuation. sound pressure level (SPL) output. harmonic distortion. seasurenent of the rise and decay times of the stimulus. and bone-conduction. The instrumentation uti- lined in the generation and measuroment of warble-tone (the beat-frequency oscillator and spectrum analyser) was also calibrated according to the procedures specified in their respective operating aanuals. Measure- aents of the signal to be warbled. including its base frequency. SPL output. and harscnic distortion were also measured at the earphone after it had been routed through the ACCESSORY INPUT of the Haico NA-Zb audiometer. In addition to the above. daily calibration checks were made of the SPL outputs and test frequencies. Calibration for the pure-tone stinuli was consistent with the Aserican National Standards Institute (ANSI) 1969 “Specifications for Audio-store“ and also the Hearing Aid Industry Conference (HAIC) "Interi- Bone-Conduction Thresholds for Audiomotry' (bearger. 1966). calibration of the warble-tone stisuli followed the rationale and method given in Appendix B. The instrumentation and procedures involved in the calibration checks and the results of these measurements are recorded in Appendices C through H. Stinuli Eh Stiluli employed during the experiment consisted of pure-tone air- and bone-conduction and warble-tone signals. For the warble-tone stimuli. the base frequency (a pure-tone) was frequency modulated so that frequency deviations occurred in a sinusoidal sanner both above and below the base frequency. 2? hmiaental Procedures hch subject '13 hearing threshold levels were seasured aonaurally on six separate occasions for a total of fifteen hours per subject. This averaged 2'} hours per session and followed the outline for each session as listed below. Session #1 . A. Monaural pure-tone air- and bone-conduction thresholds at six test frequencies (250. 500. 1000. 2000, #000 and 8000 Rs). B. Five sonaural pure-tone air-conduction thresholds at 1000 Rs. 0. Thirty cosbinations (sixty repeated measures) of aonaural warble-tone thresholds having a eenter frequency of 1000 Na . Session #2. A. Five aonaural pure-tone air-conduction thresholds at 2000 No. B. Thirty ccabinations (sixty repeated seasures) of aonaural warble-two thresholds having a center frequency of 2000 as . Session 32:. A. Five monaural pure-tone air-conduction thresholds at M00 Ks. B. Thirty cosbinations (sixty repeated seasures) of aonaural warble-tone thresholds having a center frequency of 11000 Ha . Session It. A. Five monaural pure-tone air-conduct ion thresholds at 8000 Rs. B. Thirty coabinations (sixty repeated measures) of sonaural warble-tone thresholds having a center frequency of 8000 Rs . Session 15. A. Five nonsural pure-tone air-conduction thresholds at 500 Ha . B. Thirty conbinations (sixty repeated measures) of monaural warble-tone thresholds having a center mquency of 500 III . 28 Session #6. A. live uonaural pure-tone air-conduction thresholds at 250 Hs. B. Thirty cosbinatiens (sixty repeated seasures) of sonaural warble-tone thresholds having a center frequency of 250 Rs . Threshold Deter-mation. Threshold determination (with the exception of the initial screening testing) for both the pure-tone and warble-tone signals was obtained by an orienting aethcd of limits followed by a descending method utilising 2 dB intensity incresents. The specific instruct ions and procedures enplcyed were as follows a 1 . Instrueticas. The subject was instructed as follows: You are to listen very carefully during this test. You will hear a series of sounds. scae high-pitched and sons low- pitched. (For the warble-tone thresholds the subject was also told that seas of the tones will seen to warble and others will seen to be steady.) You are to respond by press- ing the button I've given to you whenever you hear a sound and release it when the sound disappears . It is iaportant that you listen and respond to very faint sounds. not merely when you can hen then easily. Do you have any questions? 2. Tirgsheld. The specific procedure utilised in threshold determin- ation was as follows i a. The auditory stisuli were initially arbitrarily presented at a 30 dB Hearing Level (KL). b. The intensity was then decreased in 10 dB steps with two presen- tations per level until no response was obtained on both presentations. c. The intensity was then increased by 10 dB and descents in 2 dB steps oecurred with two stisulus presentations per level to- establish a level where the subject correctly responded to 5 of 6 stisulus presentations. 29 d. The intensity continued to decrease in 2 dB steps until the subject missed 5 of 6. e. Threshold was that value where the subject last correctly responded to both stisuli at a level sinus 1 dB for each correct response below that point. f. As soon as threshold was obtained. the subject was told to relax. Pure-Tone Threshold Tests. Nonaural. pure-tone air-conduct ion thresholds were obtained at octave intervals fro- 250 through 8000 Rs during the first test session in ascending 5 dB steps (oarhart and Jergor. 1959). The purpose of these measureuents was to insure that the subject met the criterion for acceptable hearing levels for the experiaent . he- quencies were tested in the following order: 1000. 2000. #000. 8000. 1000. 500. and 250 He. The repeat measure-out obtained at 1000 Rs served as a reliability check. If the subject 's threshold at 1 000 He was not within :5 dB of the initial threshold at 1000 Hz. the subject was reinstrueted and testing was again started at 1000 Rs. Monaural. pure-tone bone-conduction thresholds were established at octave intervals free 250 through #000 as during the first test session only by the need Technique (i960) enploying narrow band lacking provided by the Maine HA-2# audioneter. These were also obtained in 5 dB steps. Frequencies were tested in the following order: 1000. 2000. #000. 1000. 500. and 250 Rs. The repeat seasuresent at 1000 He followed the ease rationale as for air-conduction testing. The purpose of testing bone-conduction was to establish the subject 's ability to meet the requireaents specified for norsal listenersu-no air-bone gap. 30 After the criteria for normal hearing had been established. five pure-tone airbconduction thresholds were obtained for the frequency being tested utilising the descending threshold procedure in 2 dB steps as previously described. These were obtained at specified times during the experiment with a single threshold seasurement taken prior to the first warble-tone cosbination. and after the fifteenth. thirti- eth. forty-fifth. and last warble-tone combinations. These were then averaged and represented the pure-tone thresholds with which the warble- tone thresholds were conpared. Hhrble—Tone Threshold Tests. Honaural warble-tone thresholds were obtained in 2 dB steps with center frequencies of 250. 500. 1000, 2000. #000. and 8000 Hz utilising thirty coubinations for a total of sixty repeated neasures of frequency deviations and uodulation rates. The specific coubinations used were derived from pilot data on two listeners who set the same requireaents for normal hearing as did the test subjects. The ear tested was the right each for each subject. The order in which each subject was given a specific cou- bination of frequency deviation and uodulation rate was randosised so as to mini-ire tesporal effects on thresholds. Table 1 shows the thirty conbinations for a total of sixty repeated seasures of nodula- tion rates and frequency deviations used in this study for a single test frequency. The same cosbinations were available for each of the warble-tone center test frequencies. Appendix I shows the random- isations of cosbinations of frequency deviations and uodulation rates for each subject per test session. The repeated neasurenents were obtained during the sane test session. In Table 1 the legend in each cell. i.e.. (01,1) denotes the combination (C) of frequency deviation Thbl. 1e seasureuents were obtained. 31 Combinations (C) of frequeno deviations (1st sub- script) and nodulation rates (2nd subscript) warble-tone at each test frequency. utilised to produce the The table shows that repeated F===——-——————_—_====fi hequency Deviation in Porcent Modulation Bate $1.096 23.0% to.” 110.0% £50.09: Measure 1 01,1 03,1 c6.1 c10.1 c50.1 1/“Be Measure 2 01,1 63,1 06.1 010.1 “50.1 Measure 1 G1,z 03,2 66.2 c10,2 °50.2 Z/BCCe Measure 2 “1.2 03,2 c6,2 ”10.2 c50.2 3mm 1 01.1. 03.1. can 010.1: 050.4 #/sec. Mare 2 cm “3.1. can 010.1; c5M Measure 1 01,3 03,3 c6.8 010.3 c350.8 B/QOCe Measure 2 01,; 03.8 66.8 c310.8 c‘50.8 hum 1 01.16 03,16 06.16 010,16 050,16 16/b03e Mm 2 ‘21.16 63.16 06.16 c10.16 “50.16 heasure 1 61,32 03,32 06.32 °10.32 c50.32 32/seo. Measure 2 01,32 ‘23,32 c6.32 c10.32 c50.32 ;——-——————-J-——--—:“ ——{—— 32 and ucdulation rate utilised. The first subscript denotes the Requency deviation in percent and the subscript following the ccua denotes the acdulation rate. In Appendix J the specific frequency deviations for each test frequency are given in both percent and Ho along with the aodulation rates. Also included is inforsatios on the FENDER! DEVIA- TION position of the beat-frequency oscillator. the VOLT SCALE and out- put voltage ef the function generator and the Its/DIV scale on the storage oscilloscope required to produce and secure the warble-tone stisuli. In obtaining warble-tone thresholds for each subject in each test session the following pecedure was followed a 1 . Palm Prggggurc for Iarble-Tone Thresholds . ' a. The center frequency of the warble-tone was selected by varying the rain frequency dial of the beat-frequency oscillator and it was uonitored with the mquency counter until the desired center or base frequency was obtained. b. With the sodulation rate set at # per second. the V0 meter of the Thico NA-2# audioseter was adjusted to give a "0' '0 reading through the ACCBSORY INPUT . 2 . Test Procedure for each warble-Tone Threshold . a. Appendix I was consulted to determine the coabination of ne- quency deviation and ucdulation rate to be used for each thres- hold determination. b . With the knob narked MODULATION FREQUENCY of the heat-frequency oscillator turned to "kt." and the knob uarked FRNUENCY DEVIATION to the frequency deviation required. the external function generator was varied in: 33 1) its output frequency to obtain the desired aodulation rate. and 2) its output voltage to establish the mquency deviation desired. (The relationship of the output voltage of the function gener- ator to the FREQUENCY DEVIATION setting required for a specific range of warble-tone in Ha had previously been systeuatically explored with a storage oscilloscope and associated spectrum analyser. Appendix J gives the output voltages required along with the beat-frequency oscillator FENDENCY DEVIATION setting needed to obtain the desired frequency deviat ion for each warble-tone oombinat ion .) c. The center or base frequency was readjusted with the FINE FRE- Qunwcr SCALE ALIGWT of the beat-frequency oscillator.“ d. The descending warble-tone threshold was obtained following the procedures previously outlined. e. Steps ”a” through "d" were repeated for each warble-tone thres- hold combination fcr all subjects during each test session. 1’Even though a single base or center frequency was utilized for the warble-tone coabinations on a given day. changes in the MUENCY DEVIATION setting of the beat-frequency oscillator resulted in shifts of the center frequency. To couponsate for these shifts. the FINE MUHCY SCALE ALIGNMENT of the beat-frequency oscillator was adjusted until the desired center frequency was again obtained. CHAPTER IV REULTS AND DISCUSSION This chapter includes the results of the pure-tone and warble-tone threshold neasureaents along with the presentation of the findings relative to the questions proposed. This is followed by a discussion andasunnary. Luge-Tone Threshold Hoopla-.3 The criterion for “normal” hearing specified that thresholds should be at least 15 dB re ANSI-i 969 reference levels for octave frequencies free 250 through 8000 He in the test car and with no air- bone gap. The initial screening was performed using ascending 5 dB steps according to the method advocated by Carhart and Jerger (1959)- For the experiaent . descending pure-tone air-conduction thresholds were obtained prior to the first warble-tone coubination and after the fifteenth. thirtieth. forty-fifth. and last warble-tone cosbinations. Table 2 presents each subject's right ear pure-tone air-conduction descending thresholds along with the scan threshold in Hearing Threshold Level (HTL) and Sound Pressure Level (SPL). Multiple usasurenents of the air-conduction thresholds were obtained to allow for better averaging of threshold since preliuinary testing indicated that they were not as consistent as warble-tone thresholds. Figure 3 displays graphically the Hearing Threshold Levels according to the ANSI-1969 Standard. 3# 35 Thble 2. Monaural. descending pure-tone air-conduction thresholds obtained during each test session for each subject at six frequencies along with the mean HTL (ANSI-1969) and SPL threshold values. F=================3""—-'1=======T=======T===============F============ Subject Frzfiufizcy Test 1 Test 2 Test 3 Test a Test 5 ETEEP‘QPL, {l 250 -3.0 -8.0 0.0 -2.0 -8.0 -3.» 22.0 500 -3.0 -5.0 -3.0 -6.0 -6.0 -h.6 7.0 1000 -9.0 -5.0 0.0 -8.0 -3.0 -5.0 2.0 2000 -5.0 0.0 -3.0 3.0 -6.0 -2.2 6.8 #000 into 5.0 17.0 10.0 11.0 12.2 21.7 ‘ 8000 #111» 10.0 13.0 12.0 1u.0 12.0%?!)- #2 250 0.0 2.0 -2.0 1.0 2.0 1.b 26.8 500 0.0 0.0 4e0 2.0 '3e0 -1.0 10e6 1000 -#.0 .u.0 1.0 -6.0 -5.0 .4.0 3.0 2000 -2.0 -#.o -6.0 -5.0 -u.o -#.2 #.8 #000 9.0 5.0 9.0 7.0 6.0 7.2 16.7 8000 8.0 13.0 12.0 10.0 7.0 10.0 23.0 F's—r75. -... -... -... -... -... -... .... 500 6.0 6.0 8.0 6.0 6.0 6.0 18.0 1000 9.0 8.0 5.0 2.0 6.0 6.0 13.0 2000 8.0 6.0 h.o 10.0 11.0 7.8 16.8 #000 6.0 8.0 9.0 9e0 9.0 8.2 17e7 8000 8.0 11.0 8.0 0.0 2.0 6.6 19.6 = *Due to an initial recording error the earphone SPL outputs are 0.1 dB too weak at 250 Hs and 0.1 dB too strong at 500 Hz. 36 -10 i ' kt ..., a— ‘\\ o _P_-.—-¢b\u ..... . -.- \ .... a 10 .....-"- - ,— fig 20 3% 3° ‘ #0 g§ u35j 50 at g: 6. [-1 ‘s’g 7° 3% 80 _J Subjectfl 9° h4 Subject #2 -------- ; Subject #3 -------- ----- 100 I 110 Figure 3. Mean uonaural pure-tone airuccnduction thresholds for the three subjects used in the experiment. These averages are based on five tests employing descending 2 dB steps of attenuation. 37 warble-Tone Threshold Results Right ear monaural thresholds were obtained for thirty warble-tone conbinations and thirty repeated seasures for a total of sixty at each of the following center frequencies for each subject. 250, 500, 1000, 2000. #000. and 8000 Ha. Appendix K gives both the Hearing Threshold Levels (HTL)5 and Sound Pressure Levels (SPL) for all subjects under each of the warble-tone cosbinations for each frequency. The data shows that there is variation in the warble-tone thresholds as a result of both the frequency and the warble-tone cosbination used. The quan- tity of nusbers representing threshold is too great to display graph- ically the thresholds for each cosbination for each subject and for each frequency. However. it is important to view the differences and trends in the warblevtonc thresholds as they occurred. To display these differences and trends and derive statistics that could be scan- ingfully sanaged. each subject's nean pure-tone air-conduction threshold in SPL was subtracted from that case subject's nean warble-tone threshold in SPL (for each repeated scasure cosbination) for the ease frequency. The difference scores that resulted were then averaged and plotted as dB differences fros an arbitrary sero reference line representing the pure-tone threshold. The resultant individual subject and scan dB difference scores for each warble-tone cosbination and frequency are given in Appendix L. Figures #a through 9b display graphically these scan dB differences for each warble-tone cosbination. If at a particular frequency the 5HTL for warble-tone threshold is the dial setting re 0 HTL when the audioseter is calibrated for warble-tone. (See appendix D.) 38 hequency - 250 Hs Modulation Bate dB Difference iii 33% 16% 1'1 0% 250$ Frequency Deviation Figure #a. lean dB difference scores for each warble-tone frequency deviation with modulation rate as the paracetcr. Frequency Deviation '5 " \~ 31% -# - \‘\ 1'35 """" ‘a\ 16$ .---------.. -3 — \ 110% — — — s \.__-_. 150% —-—-— 3 \ g gig-Ii .. r a ‘go //’ ...) 1 2 # 8 16 32 Modulation lite Fibure #b. lean dB difference scores for each warble-tone sodulation rate with frequency deviation as the paraseter. 39 ”0111wa n 500 H! dB Difference 1/uce 2/sece #/sece B/BOOe 16/scc. 32/”ce 11% Figure 5‘s 16% t10% Frequency Deviation 150% loan dB difference scores for each warble-tone frequency deviation with sodulation rate as the parascter. Frequency $11 13% :61 $105; 350% 1 2 main. Noduat ion Rate 8 16 32 Mean dB difference scores for each warble-tone sodulation rate with frequency deviation as the parascter. #0 Frequency - i 000 Rs ~.\. ‘. ~ dB Difference “(burnout-to I r- Hodulation fits .. 1/BOCe “a Zluce ------- ‘ _ #/sec. ------------ \ 8/sec. -- —— —-—» \ — 16/scc. h—-——--+ 32/303e 11% 23% 16% 110% 350% Frequency Deviation Figure 6a. lean dB difference scores for each warble-tone frequency deviation with sodulation rate as the parascter. '3 -2 _. N\\\ -1 r- """“"\‘T 8 0 g 1 -' -——---—-—- s 2‘ \ a: 3L. \‘ 53 # _ Frequency iation \ ‘ 1176 h \‘ 5h- ;2; ___________ q \‘I"~\‘ 6r- so; ————~ \~ 150% —"—‘-‘ 7 1 2 # 8 16 32 hodulat ion Rate Figure 6b. lean dB difference scores for each warble-tone modulation rate with frequency deviation as the parascter. #1 Frequency .- 2000 Ha 32/88O e Modulation Bate — 1/863e _ Z/BOce ————— '— n/SOCe h """"" "' _ 8/seo. ~— — 16/sec. -—-—-—1 —§— --fl- 11% “Eur. he 23% 36% 110% hequency Deviation 1'50! Mean dB difference scores for each warble-tone frequency deviation with sodulation rate as the parascter. -7 \ Frequency Deviation ‘6'- \~\ in; -5— ~ is; -- --------- .4... \. 110% ——--— \ 1:505 h-—-—-— -3— ~\ —/ 3-2.— / \\ g -i — \\ an -o 3'5 -------~.. / f)— 1 — \ R..— ~ . % h k // / 3 1 Modulation Rate Figure 7b. Mean dB difference scores for each warble-tone modulation rate with frequency deviation as the parascter. 11% 13% 16% 1'1 0% :50; Frequency Deviation figure 8a. lean dB difference scores for each warble-tone frequency deviation with nodulation rate as the paraneter. -10 ’ Frequency viation '9 ‘ \~ :19: -8 P \‘N *3“ h ------ \ 16% -----------d -7 - \ i153; :. :1“ g -6 - \\ \~ -5 y— \ ~ — _ _‘ y. \ \ I / \\ A a -3 _ _;2§‘ —-:,—o'-’ ...-... '/ X '=:: ><’ \/ ~------------ >- 3.. -2 +— ‘T / 1 N -1 - \ / 0 1 2 it 8 16 32 Hodulnt ion ht. Figure 81:. Sean dB difference scores for each warble-tone nodulation rate with frequency deviation ae the motor. “3 5338.3 23 no 33.933 52338.“ 5.2. one.” no." add—oo- 33.63.33 code you nouoou 8:80.33 mu ado: .pm engr— oanm conned—co: «m 3 m a N « Ill, .83 ..lllll mo .1 ......... 5w. \\\\/// lulu: m9 n 1111/ on .. k u I I [Haloaben 13:03.5 LT... a.» -. . I WNLI / NI, v\\\ 0000 [I II /‘\\/ loo; .l // I ||||||||| II lllf l // .\. ./ L I ‘ I I. \ /.II.I|‘|\ I/ ./ mm- own man mm- Jove-anon on» no 3e..— 333.60- 5: 33.933 5235399 3070.382. :93 Mom nouoou 028.3836 mu :3: tom earn 8338: unsung «on». :3» new no..." Rn. \ I / \\ J \ , ? X \ S ‘0‘”! ll ee t t \\ k \ \ .I. \\\\\ \i\~ee \ i \ ... \.x 625m 1 ~\ al .oon\m« L» LTIIIIL .oeo\m l \ w an ........ L .oou\: I s \.. filnllnll .oou\N \\.. .oon: l i. {/%x V {\f/ l \ ... 8.. 250 I bong—g mm- fl... 3. mm. 1.4 warble-tone threshold was better (required less SPL) than by pure—tone, then the difference shown in Figures 11a through 9b would be negative. Likewise, a positive difference loans that the warble-tone is poorer than the pure-tone threshold. The data for each frequency are shown two ways: first, with sodulation rate as the paranoter and: second, with the frequency deviation as the peraaeter. A cursory observation of the warble-tone thresholds shows tut they are not always cosparable to the pure-tone thresholds (represented by the ”0" reference line ). Also. certain trends occur with respect to the warble-tone cosbination utilised. A sore detailed analysis of the results relative to the original questions of interest now follows. warble-Tone ‘lhresholds Versus fluency Figures he. through 9b show that there are variations in warble- tone thresholds as a function of frequency. sun. the differences are not great (with the exception of the 250% frequency deviation cosbin- at ions) warble-tone thresholds are generally poorer than the pure-tone thresholds at 250. 500, and 2000 Hz and better at 1000, 4000, and 8000 Ha. Threshold is generally poorer at 250 Ha than the pure-tone reference except for the 150% frequency deviation (Figure he.) which shows better thresholds. The threshold of the 150% frequency deviation is also better at low sodulation rates than at high sodulation rates (Figure hb) but this does not appear to generalise to the other frequency deviations. If the 250% frOQuency deviation condition were excluded at 250 Rs no basic differences in warble-tone thresholds would be apparent. 45 Harble-tone thresholds are generally poorer than the pure-tone threshold at 500 Hz (Figures 5a and 5b) with the tsos frequency deviation giving the poorest threshold. Again, if this frequency deviation were excluded fron the data, no consistent differences in thresholds for 500 Ha would be evident. There is a tendency, however, for higher sodulation rates to result in poorer thresholds at the higher frequency deviations. At 1000 Ha the warble-tone thresholds are better than the pure- tone thresholds (Figures 6a and 6b). The single notable exception is the 150% frequency deviation. The effect created by this frequency deviation is lost noticeable at the higher sodulation rates where a difference (poorer) up to approximately 6 dB occurs between the warble- and pure-tone thresholds. Again. as in the previous frequencies, if the 150% frequency deviation condition were elisinated, essentially no differences between the warble- ~ and pure-tone thresholds would occur. Alnost all cosbinations of warble-tone (except the 150% frequency deviation conbinations) resulted in poorer thresholds than obtained by pure-tones at 2000 H2 (Figures 7a and 7b) and a reversal for the direc- tion of change occurs fros that seen at 500 and 1000 Hz. The change is that the 150% frequency deviation condition now gives the best or nest sensitive thresholds and .is better than the pure-tone threshold. The nest sensitive thresholds occur at low sodulation rates and decrease in sensitivity at high sodulation rates. Again, if the 150% frequency deviation condition were not included, all of the thresholds would be similar and slightly poorer than the pure-tone thresholds. At #000 as all warble-tone thresholds are better than the pure- tone reference. In addition, distinct differences in thresholds begin 46 to appear as a result of the warble-tone cosbination eaployed. Figures 8a and 8b show that the nest sensitive (best)thresholds are those associated with the £501 frequency deviation condition and that the least sensitive thresholds are those associated with the tiflifrequency deviation condition. In addition. better thresholds have a tendency to be associated with lower sodulation rates. Distinct differences in threshold due to the warble-tone cosbin- ation are evident at 8000 Ha (Figures 9a and 9b). In general. warble- tone thresholds tend to be better than their pure-tone counterpart. Differences due to frequency deviation show better thresholds as the frequency deviation increases. Slightly better thresholds are again associated with lower sodulation rates. An interesting phenosenon occurs in the trends associated with warble-tone thresholds. At 250 as the general trend is for the wider frequency deviations and lower sodulation rates to be associated with the nest sensitive thresholds. However, at 500 Hs this trend is sees- what reversed showing a tendency for the wider frequency deviations and higher sodulation rates to produce the poorest thresholds. The trend at 500 Hi also holds true at 1000 HI. and actually becoses sore noticeable. At 2000 H! the trend with warble-tone thresholds is sisilar to that reported for 250 as. and continues through #000 and 8000 as. Ihat this indicates is that there see-s to be two ”changeover" regions with respect to the types of threshold responses that night he expected: one between 250 and 500 as and the other between 1000 and 2000 HI. table 3 shows the nean warble-tone dB difference scores free the pure-tone thresholds and standard deviations for all coabinations of frequency deviation and sodulation rate at each test frequency. The 47 Table 3. Mean* warble-tone dB difference thresholds free the pure-tone thresholds and standard deviations for each test frequency. Frggufizcy "5‘" S:::EE:§L 250 0.06 1.68 500 1.17 1.50 1000 -°.17 2.~4 2000 0.36 2.40 4000 -3.0h 1.9“ 8000 ~5.37 9.86 *All conbinations of frequency deviation and sodulation rate were averaged for the three subjects. order of frequencies having the least to the nest variability is as follows: 500, 250, #000. 2000, 1000, and 8000 Rs. gaggle-Tone Versus Pure-Tone Thresholds The prisary purpose of this investigation was to coapare pure-tone and warble-tone hearing thresholds using various coabinations of fre- quency deviations and sodulation rates. Figures ha through 9b show the aean aonaural dB‘difference scores froa the pure-tone thresholds and are plotted in two different ways so that threshold effects of the warble-tone coabinations used can be seen. then though the data in those figures have been condensed fro. the original results, it is still difficult to answer one of the rain questions asked by this investigation: ”How do warble-tone thresholds at various conbinations of sodulation rates and frequency deviations conpare with conventional, aenaural pure-tone thresholds?" 48 Figures 10. 11. and 12 show the effects of each warble-tone coa- bination on threshold across all test frequencies. The ieplication fro. such an analysis would be that the warble-tone cosbination(s) with the least variability or having a constant variability free the pure- tone thresholds would be best for threshold testing. In Figure 10 the 11% frequency deviation with its various nodula- tion rates shows little change in threshold fro- one frequency to the next with all cesbinations fairly cosparable to the pure-tone thresholds. A possible trend is that of less variability around the pure-tone thresholds with increased sodulation rates. However. this speculated reduction in variability is quite suall and would probably have little or no effect in clinical testing. The 13% frequency deviation conditions also show relatively oospsrsu. warble- and pure-tone thresholds across all frequencies. It appears that under the 16% frequency deviation conditions (Figure ii) that lower frequencies tend to be associated with slightly poorer thresholds than the higher frequencies. This trend becoaes sore noticeable in the 1105 frequency deviation conditions with thres- hold isproving approxisately 5 dB free 250 to 8000 Ha. Further, warble- tone thresholds seen to becose poorer with increased sodulation rates. Figure 12 shows the 350% frequency deviation cosbinat ions and it is quite evident that the warble-tone thresholds for each cosbination vary as a function of frequency. This variation covers a range of approxisately 32 dB with 8000 Ha having the greatest variability. In addition, the trend showing poorer thresholds with increased sodulation rates (discussed for the 1’61 frequency deviation conditions) is acre dB Difference I.» 3.. -6 #NO Figure 10o “9 ~2I° 59° I" 2r “f —h%‘1/“Ce " /\/\ _/ v 1 J I I I_ "I I I I I l r-tlx - 2/sec. _ IV V I I I — I I I I I I -t1% - II/see. “' /\/\ I— I I I I I I 11%-32/sec. /\/\ v Ilj _._r \ I I I I I I Frequency In Hs 8k I-ZFO 5'00 1k 2}! “I! PiBSS/\-1/se|c. L. ...V P I I I h 1’35 - I2/se'c. I - /\ /\V F “/ V I I I I I I "l I I I _ +35- lit/”Ce __ //\V \ I I I J J I I I I I I I— m - 16/‘0Ce A _ \/ \ i I I I I I P I I I I I I — 33% - 32/sec. :tA‘A lean differences in dB between warble-tone and pure- tone thresholds for the warble-tone coebinat ions indicated in each emph- ' 50 hequency in Ha 250 500 11! 2k III: & 250 500 1k 2k 15k 8k -6-I I I I I I ”I I I I I I J} “'265 - 1/800. _ 110% 'N -2_ /\ _ o_7/\v AV 2— ... 4 I I I I L I I I I I I L j—Iw‘Iz/I I I I -Iflo%I2/I I I I —. - IOOe — - 806. -2_ / - r z— — V 4 I I I I I L I I I I I I :2”I I I I I I "I I /l I I I ’16%-#sec. -nox-u..s. ~2h / /\ — / °“:7A\/ v § 2- L. 8 n J I I I I I I L I I I I «‘4’ 2'6”” I I I I I I"! I I I I I 3 "I-té%-8/sec. —:I:10%-8/sec. -2» — 2 \/ V ...—JV 1‘ L I I l I I I I L I I I '6'I I I I I I [I l I I I I AI *- 16% - 16/sec. 110% - 16/sec. -:_ \//\ —/\//—— :_I I I I I I L I I l I I ’6_I I I I I I "I I I I I 4P1’61-32/sec. 'flM-BZ sec. -z_ .. 0 WA AV 12.—I I I I I I LVI I I I Figure 11. Mean differences in. dB between warble-tone and pure- tone thresholds for the warble-tone cosbinations indicated in each 61"?”- -21 _ 250% - 1/sec. 2?0 5?0 1'1! 21: III: I 51 hequency in Rs . 8k 2?0 500 1'k 21: (III! 8k I : 1.50% "’ 8/830 e _ I- dB Difference LI I I I I _t5o%'16/B.Oe I; r I ..a N IFTII I u I Figure 12o ... L. r. I. L. I I I I l _ 1.50% "' 32/306. IIII I I I I I I I Mean differences in dB between warble-tone threshold and pure-tone threshold for the warble-tone cosbinations indicated in “Oh mp1s 52 noticeable here except at 8000 as. Poorer thresholds by approxiaately 5 dB occur with sodulation rate increases free 1 per second to 32 per second. In general. the conclusion free the presentation of the thirty warble-tone cosbinations utilised across frequencies indicates that for all practical purposes, warble-tone coabinations up to and includ- ing frequency deviations as high as 210%; and sodulation rates as rapid as 32 per second result in little or no noticeable differences in warble- and pure-tone thresholds. However. beyond the liaits Just specified, noticeable differences exist that night preclude the use of various warble-tone cosbinations in routine hearing testinqunless special calibration or correction factors are taken into consideration. Sons of these differences (particularly at 8000 He and the 150% frequency deviation) are so great that even nor-a1 calibration procedures say not be able to correct earphone sound pressure output levels to account for these differences. Changes in frequency deviation seen to have greater influence on warble-tone threshold than do changes in sodulation rate. With frequency deviation, the effects on threshold have little clinical significance (differences greater than t5 dB) until frequency deviations beccse larger than.in%. with the sodulation rates utilised there appears to be little effect on threshold. There scene to be acne effect (producing poorer thresholds with increasing rates) at the high frequency deviations but the resulting differences are not large and would be of little significance in routine clinical testing. Consequently, how do warble-tone thresholds at various coebinations of sodulation rates and frequency deviations coapare with conventional, 53 nonaural pure-tone thresholds? In general, any cosbination of warble- tone sodulation rate and Requency deviation up to and including 32 per second and 11 0% respectively should produce good agreeaent between warble-tone and conventional pure-tone thresholds for noraal hearing Idfltle Relations Aaogg Ruble-Tone Threshold Rankings by Subjects What are the relations along the threshold rankings of the various warble-tone coabinations by the subjects? This question was asked to deter-inc intersubJect reliability of warble-tone thresholds. The null hypothesis is that the rankings are unrelated. A seasure that allows this kind of association to be detersined on acre than two sets of rankings is Kendall's Coefficient of Concordance (V) which bears a linear relation to the average correlations taken over all subjects, except that only values between 0 and +1 can occur. The coefficient of concordance is an index of the divergence of the actual agreeaent in the data free the aaxiaus possible (perfect agree-eat). Since tied ranks occurred frequently in the warble-tone thresholds and tended to depress the value of II, a correction was introduced which slightly increased the value of II over what it would have been if uncorrected (310501. 1956). Table II sue-arises the results of the coefficient of concordance for each of the test frequencies and rankings given in Appendix II. Hith an N larger than 7 (N - 30), the probability associated with a calcu- lated (:11 square (x2) representing II is apprexiaately distributed as an square with N - 1 degrees of freedos (Siegel, 1956. P. 236). 54 Table lb. Sunnry of coefficient of concordance (II) of inter- subject reliability of warble-tone thresholds. Fr Coefficient Calculated '13qu of cm Square Concordance value 250 W I 0o27 23049 500 II - 0.50II 03.50% 1000 0’. O.76*** 66.12*** 2000 W - O,58** 50.116“ #000 I! - 0.II9* 02.6% 8000 w .- 03mm 54.33”“ *p.£ 0.05 '*fip.:£ 0.01 ***p. ..<. 0.001 Results of the coefficient of concordance show that the null hypothesis is rejected (p._<. 0.05) at 500, 1000, 2000, #000. and 8000 Rs. The interpretation is that the rankings by the subjects for the various warble-tone cosbinations are related. with the exception of 250 Hz. while the null hypothesis at 250 as was not rejected, this was possibly due to subject three's deviation free the threshold pattern exhibited by the other two subjects. The significant value of 9 say be interpreted as leaning that the subjects applied essentially the ease standard in perforaing the thres- hold task with the thirty conbinations of warble-tone thresholds. It should be eaphasised that a high or significant value of H does not scan that the orderings observed are correct. In fact, they say all be incorrect with respect to acne external criterion. 55 Effects of Modulation Index on warble-Tone Threshold It has been suggested that in nor-a1 ears for a given modulation index (ratio of frequency deviation in Hz to the sodulation rate at a given frequency) better thresholds are obtained with saaller frequency deviations (Dallos and Till-an, 1966: Young and Herbert, 1970). Dallcs and Till-an (1966) initially warned against drawing sweeping generalisations froa their data since it was based on one nor-a1 hearing subject and a patient with acoustic neurinoaa tested at 500 Rs. Young and Herbert (1970) tested four noraal and five subjects having a sensorineural loss at 1000 as to atteapt to explore further the work of Dallas and Till-an. They concluded: For a given nodulated index, better thresholds were obtained with snallor frequency deviation in nor-a1 ears. In abnor- aally adapting ears, the threshold reaained unchanged or increased or decreased for a given sodulation index (p.7). The possibility that an ”equivalent sodulation index“ of 16 as suggested by Dallos and Till-an before stable threshold could be traced in abnor- aally adapting ears was not confirsed. Table 5 gives the dB differences between warble- and pure-tone thresholds and the sodulation indices (HI) for each of the warble-tone coabinations used in this experiaent for each frequency. The purpose in exaaining these data was to deternine if the sodulation index exerted any influence on the warble-tone thresholds obtained. Even without plotting graphically the data in Table 5 it is clear that with the linited variability in warble-tone thresholds (either across frequency with a single warble-tone cosbination or within a given frequency with a variety of warble-tone coabdnations) and with the large range of sodulation indices. that there is no systenatic effect between sodulation 0.0«3 0.0 _ 0.00 9«- 0.0« 0.3 0.3 90- m; m.« «.0 «.3 0 - new 90% «.0- 0.0«3 90- 90s 93 0.00 90- 0.3 90 2. «.0 a - R0...” 9033 «.m- 0.3« n.«- 0.0«3 “.0 0.00 90- 900 3.0 0.3 93 « - men 908 a.«- 0.8.3 9? 0.0.3« 90 0.0«3 0.3- 0.00 90- 0.00 90 3 - use 0.3 0.3 m.« 0.«- «.m «.0 93 0.«- 0.0 90- 3.0 3.0- «m - an.» 900 3.« 93 3.0.. n.« 0.3 «.0 3.0- 93 0.3 0.0 0.3 03 - um“ 0.0m 3.3 0.0m 9m- 93 90 n; 93- «.0 90 93 93 o - an“ 0.0«3 90 0.3 0.3- 0.00 «.0 93 90- mg 0.0 «.0 3.0 e - as" 0.0:« 0.0 0.0«3 9«- 900 «.0 90m «.3- 0.3 0.3 04. 0.3 « - um“ 90? 90- 0.0% 3.0- 0.0«3 e.« 0.00 m.«- 0.00 «.3- 0.3 3.3 3 - an». 0.0 93 n.« 93- «.3 «.0 90 93- 0.0 90 3.0 90 «m - mm 0.03 «.0 9m 90- n.« +3.3 «.3 0.0- 90 90 0.0 0.0 03 - 3w 0.0« 0.0 0.03 0.0 9n 9« m.« 0.«- «.3 «.0- 90 «.0 m - R3“ 93 0.0 0.0« 3.«- 0.03 «.0 9m 9«- n.« 0.0 «.3 3.0 a - an. 900 9« 90.3 3.«- 0.0« 0.3 0.03 m.«- 9n 0.3 m.« 3.0- « - 3.... 0.003 3.0 0.0« 0.«- 90.3 n.« 0.0« 90- 0.03 90 90 93 3 - an 3: B 33. 0.3. 3: 0.3. 3: 0.3 3: E 3: 93. e03¢33n8o 000« 000.3 000« a ,. 0003 00m 03 «Se-.33. am 5 nosesuouh .38.: .838380 Sop-03.3.»... 2:. .30 .33. 8.3 35 80333 33$??- 2:. £3: «:03. 3.32382... 83-053 23 8.3.3 me :3 3.5 gauge 3.33.22“. once-.3333. 5.: .0 .Bee 57 0.00« 0.0? 0.0«3 0.3- 0.«0 0.0 «.30 90 0.3 0.0 0.« 93- «0 03003 0.000 0.0«- 0.00« 0...- 90«3 «.«- 0.«0 3.0 «.30 3.0 0.3 3.3- 03 0300... 0.0003 0.0«- 9000 0.0- 0.03 «.«- 0.0«3 0.0 0.«0 0.« «.30 n.«- 0 030033 9000« 0.0? 0.0003 90- 0.000 0.0- 0.00« 9.3 0.0«3 9m 0.«0 n.«- 0 03003 0.0000 «.0«- 9000« 0.0- 0.0003 0.0- 9000 3.3 0.00« 0.0 0.0«3 0.0- « 0303. 0.0000 0.3- 9000.3 3.0- 9000« 3.0- 0.0003 3.3 9000 0.0 0.00« 0.0- 3 R03. 900 «.0- 0.0« 0.0.. 0.«3 93 «.0 0.3- 3.0 3.0 0.3 0.0 «m 0303.... 0.003 0.«- 0.00 3.«- 0.0« 0.« 0.«3 3.0 «.0 93 3.0 3.« 03 0303.3 0.00« 0.«- 0.003 90- 0.00 «.« 0.0« 0.0- 0.«3 3.« «.0 0...« 0 33.3 900.3 0.0- 900« 90- 0.003 «.0 0.00 0.0 0.0« 0.0 0.«3 3.0 0 03033 0.000 0.0- 903 0.? 0.00« 0.3 0.003 93- 0.00 0.0 0.0« 0.0 « 03033 0.0003 «:3- 9000 0.0- 900.3 «.0- 0.00« 0.«- 0.003 0.0 0.00 0.0- 3 03033 90.0. 0.0 0.3 0.«- 0.« 0.« 0.0. 0.0 0.3 0.3 0.0 0.0 «n 0303.. 0.00 0.3- 0.00 0.«- 0.3 0.« 0.0 3.0 0.0 90 0.3 0.0 03 030“ 30 0.3 3: 0.3 3: 0.3 3: 0.3 3: 0.3 3: 0.3 00383080 0000 0000 000« 0003 000 0.0« 0003-030.3. um 33.... hosesg 308030080 0 0300.3 58 index size and the dB difference scores. These consents should be reserved at least for the subjects studied (a snail sample of nornal listeners). Both Dallos and Tillman (1966) and Young and Herbert (1970) reported that at a given sodulation index better thresholds were obtained with smaller frequency deviations. The test frequencies free which these consents were directed were 500 Rs for the forner authors and 1000 Hz for the latter. The results of the present investigation indicate that it would be hazardous to generalize these conclusions as shown by Figures 13 and 14. ‘lhese figures reveal no distinct trends for a given sodulation index with the possible exception being 8000 Hz. At this frequency better thresholds tend to occur at a given MI with increased frequency deviation. However, if sodulation indices are considered which include the 150% frequency deviation conditions, better thresholds seen to occur with wider frequency deviations at 250, 2000, #000, and 8000 Ha. Poorer thresholds at a given HI occur with wider frequency deviations at 500 and 1000 Hz. The latter state- sent is consistent with the findings of the two studies cited. With respect to the sodulation index and sodulation rates, poorer thresholds generally occur with lower sodulation indices for all fre- quencies and frequency deviations. Upon considering the effects of the sodulation index on warble- tone thresholds, no consistent generalisation is evident that one or a cosbination of indices provides a guideline in threshold prediction when testing noml listeners. 59 ....... I 3003 ------- 303.3 new um“ ............... «33 aseonem s3 seavsaben senescenu on» ad sodvsa>ee bonesaenm .nevessusn .xeusd sodvsaseos on» go couvonsn d an mm 000« and .oom eon” as eeudnaps nouvusdnloo econ-odnnsa sees you 00.8000 003.“.an Nd El .M3 seamen 03.3.03 0030.00.38: 00.0I3000 003 0 03 n q — -\ — — § . am 0903 he I l l L,l um onu 3939333310 HP 60 pseosom 33.3 no.3 33.38 hoses: gees-sash one 0.33 33033.50 5033333083 .3805 3338.300- ee... .30 8388.3 e 3 .33 0000 05 .0000 .000« as 03.3.3.5 333.333.3373 once-eases: nose Hon echoes conch—etude me 53: .0: show?— NsunH Guava; coco." 08a 00.." o." ...... 3 ... s... i s s e Jilin umoocu l [IIJI 0| Gamma up 61 Discussion Due to the ssall sasple size and variation in the range of warble- tone thresholds fros the pure-tone thresholds, a question concerning the validity of the findings of this investigation sight be raised. It is true that in routine clinical testing such of this range would fall within the clinical error generally accepted of 15 dB. However. in warble-tone testing, ssall differences say be of sore clinical signifi- cance. Recall. that when the. coefficient of concordance was perforsed to detersine the consistency of subjects to rank order thirty cosbinations of warble-tone at each of the test frequencies, that significance (p. $0.05) was exceeded at 500, 1000, 2000, 1.000. and 8000 Rs. It is rather noteworthy that this significance level was reached since there was a lisited intensity range in which the warble-tone thresholds occurred . Consequently, the results of the coefficient of concordance provide the Justification for having confidence in the warble-tone thresholds obtained. Trends in Warble-Tone Thresholds. It was stated in previous discussion that frequency deviation contributes sore than sodulation rate to vari- ations in warble-tone threshold. with this in sind it is appropriate to reiterate the distinctive patterns in threshold responses that were found. it 250 as the general trend was for the 250% frequency deviation condition to result in the best thresholds for all sodulation rates. However, at 500 and 1000 Ha this pattern was reversed with the 150% condition yielding the poorest warble-tone thresholds at all sodulation rates. Then. at 2000, #000, and 8000 Hz, the 250% condition showed a 62 pattern sisilar to that at 250 Rs with better thresholds obtained at all sodulation rates. while the frequency deviation pattern of warble-tone thresholds varied as a function of the test frequency, thresholds were always isprovsd at 350% frequency deviation conditions with lower sodu- lation rates. In the total pattern presented there appears to be two changeover regions—one between 250 and 500 HI and one again between 1000 and 2000 Ha. A first logical assusption sight be that the changes in threshold are related to the sinisal audible pressure threshold curve for husans. However. this would isply that under the 150% frequency deviation conditions better warble-tone thresholds should always be obtained since the audibility curve would be reached at lower sound pressure levels due to the “wide frequency sweep.” a: the other hand. these differences cannot be explained by individual subject variation since the patterns are consistent across all subjects (except for subject three at 250 and #000 Ha). ' Since large sasple consistency in threshold trends and the signifi- cance of deviations fra these trends is unknown, it is difficult to detersine whether subject three or the other two subjects were deviant at 250 and M00 Hs. At any rate it say be best to consider only the differences in individual patterns at these two frequencies. Because subject three holds a B.A. degree in susic. her thresholds sight be suspected to reflect a sore experienced ability to listen to frequency changes. However, if this were the case the differences that occurred would sore logically have been expected for all test frequencies for this subject and this did not happen. In fact, selected warble—tone cosbinations were repeated with no significant differences in the thresholds obtained . 63 At this tise no feasible explanation for the threshold patterns obtained is offered by this investigator. If the warble-tone threshold patterns are confined by subsequent research, it would then be appos- priate to speculate about possible acoustical. physiological, or psycho- logical factors [or interactions. Oosaisens with Previous Work. Are the results of this investigation consistent with any previous studies cosparing warble- and pure-tone thresholds? Sivian and unit. (1933) had reported that a fsw check 2 seasuresents sade on the sass individual with the warble- and pure-tone indicated no systesatic differences between the threshold values other than those due to the physical and psychological considerations the warble-tone was intended to sinisise. They used a constant sodulation rate of 10 per second and a frequency deviation which progressively changed in percent fros approxisately that at 1100 he (:50 Ha) to approxisately 10.97% at 15.000-Hs (1'1“ Rs). The results of the present investigation tend to support their findings under the conditions utilised. Peck (1970). using a warble-tons having a frequency deviation of 5% to detersine auditory thresholds in very young children. consented that it was difficult to give a precise reference level for the warbled sound- field pure-tones. However, it was his isprsssion (based on thresholds obtained on sore than 10 norsal-hsaring young adults) that the thresholds approached the ISO sero reference levels. He did not specify whether the frequency deviation was a 1'55 or a +5% variation and the sodulation rate was not given. Regardless, under the possible warble-tone cosbin- ations that could have resulted. this investigation supports his cossents. 64 An Allison laboratory Bulletin 5-; (not dated) and Reilly (i958a). suggested that better thresholds occur with a warble-tons than with a pure-tons stisulus. This investigation does not necessarily lead to the ease conclusion. ihile it is true that certain warble-tone cosbin- ations result in better thresholds than produced by pure-tones, this trend is not consistent across all frequencies, and in fact, shows poorer warble-tone thresholds at sose frequencies than by pure-tone. A sore tenable conclusion would be that warble-tone say act as a sore attention centering device and serves to circusvent response difficul- ties produced by asbient noise and tinnitus. and thus my result in thresholds which are sore consistent . However, to say that warble-tone thresholds are better than pure-tone thresholds would be a hasardous supposition. These statssents. of course. apply to nersal hearing adults only. larble-tone versus pure-tone thresholds for children and for subjects with auditory pathology asait investigation. Studies specifically cosparing warble- and pure-tone thresholds are generally not available with which to relate the results of this research However. lisited data is provided in studies by Dallos and Tillman (1966) and Young and Ihrbert (i970) cosparing warble-tone with pure-tone thresholds at 500 and 1000 Rs. while it is not possible to directly cospare the thresholds they obtained with those of the current study (because of different warble—tone cosbinat ions, psychophysioal sethod, and signal generating apparatus) there are sufficient sisilari- ties to sake appoxinte cosparisons. Dallos and Tillsan (1966) found approxisately the sass or slightly better thresholds with increased frequency deviation at 500 Hz with a single norsal listener and better thresholds with slower sodulat ion 65 rates. The present investigation showed approxintely the ease or slightly poorer thresholds with increased frequency deviation. while better thresholds with slower sodulation rates were also found in this study, the variability was not as divergent as thresholds obtained by Dallos and Tillsan. Young and Ehrbsrt (1970) recorded the thresholds of four norsal, trained listeners at 1000 Rs and found that thresholds resainsd about the sans or inprevsd slightly with increased frequency deviation. Results of the current investigation at the .... frequency do- ,not . show any effect with respect to frequency deviation. However. Young and Ihrbert 's contention that better thresholds were obtained with slower sodulation rates tends to be confined-although the isprovesent is not as asst as obtained in their investigation. A review of the previous two studies in light of the current investigation depicts sose rather interesting cosparisons. This study's results do not agree with Dallos and Tillsan'e at 500 He in that poorer thresholds were found with increased frequency deviation. Also, at 1000 Ha it is difficult to detect any consistent differences in three- holds as suggested by Young and Ehrbert. It is isportant to ressnbsr that the cosparisons being sade exclude the 1'50% frequency deviation conditions since neither of the forser stud ies esployed that wide a frequency deviation. The findings concerning sodulation rates are consistent across all three studies but differences are not as great in the current investigation. It sust be esphasised that the signals used varied soaswhat for the three studies cospared, in that the other investigations used saw-tooth wavefors frequency deviations and this study used sinusoidal wavefors deviations. Perhaps the type of wavefors 66 generating the test signal effects warble-tone thresholds in terns of sodulation rate and frequency deviation. The final point that should he ends is that there is no reason to expect that changes in thresholds are sisilar fros one frequency to the next. While this aspect should be investigated further, this research suggests that definite differences do exist. Role of the Hedulation Index. Thresholds for a given sodulation index in'nornal listeners scene to provide no significant inferention or trends with respect to desirable cosbinations of warble-tone frequency deviation and sodulation rate. In fact, a cosparison of Figures 13 and it with hb, 5b, 6b, 7b, 8b. and 9b shows that sisilar inforsation is present except that the abscissa is expanded in the forser series of figures. am In attsspting to generalize the findings of this investigation to a larger population care lust be taken because of the ssall saspls size involved. However, this does not necessarily scan that the saspls sise detracts fros the general findings presented. Recall, the coeffi- cient of concordance did reach statistical significance desonstrating that intersubject reliability of warble-tone thresholds was good. In general, substantial agreesent was found between warble- and pure-tone thresholds. However, differences were found for acne stisulus parascter conditions. These differences varied by test frequency and warble-tons cosbination (frequency deviation and sodulation rate). The results desenstrated that changes in frequency deviation had a greater influence on threshold than changes in sodulation rate. This was 67 particularly noticeable for the 350% frequency deviation conditions. While threshold changes related to frequency deviation were not consist- ent across frequencies. lower sodulation rates generally resulted in better thresholds for a given frequency deviation at all test frequencies. Poorer thresholds generally were found with lower sodulat ion indices (frequency deviation divided by sodulation rate) for all frequencies and frequency deviations. In contrast to previous invest igations, no evidence was found to support the notion that one or a cosbination of modulation indices provides a guideline for threshold prediction when testing norsal hearing adult listeners. Intersubject reliability of warble-tone thresholds was good (phi. 0.05). In addition. variability in warble-tone thresholds was small with the exception of 8000 Hz. In general. warble-tons cosbinations up to and including frequency deviations of 110% and sodulation rates as fast as 32 per second resulted in close agreesent (125 dB) between warble- and pure-tone thresholds for norsal hearing adults. CHAPTER V SUMMARY. CONCLUSIONS. AND RECOMMENDATIONS §E£EE£1 warble-tons stisulus parascters of frequency deviation and nodular tion rate were investigated to detersine their effect on hearing threshold. A Three norsal-hearing experienced listeners were individually adsinistsred thirty randosissd warble-tone cosbinations and thirty repeated seasures (for a total of sixty) at each of six octave fre- quencies fros 250 through 8000 an. The thresholds obtained were then cospared with the ease subject's conventional. pure-tone airbconduction thresholds. Each subject's hearing threshold levels were seasured sonaurally on six separate occasions. with one frequency tested per session utilising a 2 dB step descending sethod. The data were subjected to descriptive and statistical analyses to answer the questions originally posed. Descriptive seasures were . esployed to explore the significance of one variable over another in contributing to warble-tone thresholds and their cosparison with pure- tone results. The coefficient of concordance was utilised to deter-ins intersubject reliability of warble-tone thresholds. The results showed that up to and including frequency deviations and sodulation rates of 210% and 32 per second respectively. little difference between the two sethods of threshold ssasuresent can be 68 69 expected under clinical conditions with norsal adult listeners. However. beyond these warble-tone cosbinations. variations in threshold are expected to occur’and correction factors should be applied to the obtained thresholds if they are to substitute for pure-tone seasuresents. Conclusions 1. 2. 3. 5. 6. The following conclusions sees warranted: warble-tons thresholds are not always cosparable to pure-tons thres- holds. Their cosparison depends on the test frequency and warble- tons cosbination being tested. In general. warble-tons thresholds are poorer than pure-tone thresholds at 250. 500. and 2000 a: and better at 1000. #000. and 8000 us. There appear to be two ”changeover“ regions with respect to the types of warble-tons threshold responses expected. one between 250 and 500 He and the other between 1000-and 2000 as. The direction of threshold response reverses in these regions and is soot notice- able with the wider frequency deviations. Vhriability in warble-tone thresholds is ssall as a function of frequency with the exception of 8000 Ha. Intersubject reliability of warble-tone thresholds is good but scse individual subject variability was found. no evidence suggests that one or a cosbination of sodulation indices provides a guideline in threshold prediction when testing norsal adult listeners: however. poorer thresholds generally occur with lower sodulation indices for all frequencies and frequency deviations. Changes in frequency deviation. within lisits. sees to have greater influence on warble-tone threshold than do changes in sodulation 70 rate. ‘ However. while changes in frequency deviation are not con- sistent fros one frequency to the next. lower sodulation rates generally result in better thresholds for a given frequency deviation . 7. Harble-tone cosbinations up to and including frequency deviations and sodulation rates of 310% and 32 per second result in little or no clinically noticeable differences between warble- and pure-tone thresholds for norsal hearing adults . Reconsendations for Future Research lihile certain patterns of warble-tone threshold were found in this investigation. their ccnfirsation is desirable utilising a larger adult saspls on a lisited nusber of selected cosbinat ions of frequency devi- ation..and sodulation rats. Additional frequency deviations and waveforss sight be evaluated which were not included in this initial study. For exaspls. fewer fros the 11‘ “110% and sore between the 110% and 150% frequency deviation range could be evaluated. A ssaller nusber of sodulation rates could be used. although the extreses of the range should be tested. Further. a cosparison of thresholds should be perforssd using warble-tones pro- duced by triangular. positive pulse. negative pulse. positive rasp. negative rasp. and sawtooth waveforss. Varble-tone thresholds under earphones should be ccsparsd to sound- fisld thresholds on an adult pepulation. This would provide additional inforsation relative to the warble-tone's clinical usefulness. The clinical utility of warble-tone (utilising various cosbinations of frequency deviation and sodulation rate) should be systesatically exasined using a large group of subjects representing various types of 71 auditory pathology (e.g. conductive. cochlear. rstrocochlsar. and central lesions). Representative response patterns could hopefully be oestablished for the various types of auditory pathologies and thus used in differential diagnosis. After basic warble-tone parascters have been established with adults. several experisents should be replicated with children. Addi- tional questions that should be asked are: Does warble-tone result in sore consistent thresholds than the conventional pure-tone stisulus? Is the warble-tone a better attention-centering auditory signal for children than conventional pure-tones? Gan the warble-tons be applied sore successfully with young children than conventional pure-tone audicsetry? A possible clinically useful extension of warble-tone study in sound-field is its use in hearing aid evaluations. especially with children and those with language problens. By cosparing the unaided sound-field discrete frequency warble-tone thresholds with aided sound- field thresholds. inforsation relative to the use gain of the hearing aid can be obtained. The Sensorineural Acuity Level (SAL) test described by Jerger and Tillnan (1960) has generated interest as a ssthod to quantify the status of the sensorineural sschanisn. while the procedure is sinple to snploy. it is lisited in its application because of two problens. First. the occlusion effect results in underestisating low frequency cochlear reserve in conductive hearing loss cases. Secondly. cases with sensori- neural losses are likely to be overnasked due to “spread of sacking" resulting in overestinating SAL thresholds particularly in the high frequency region. A study could be conducted to detersins whether 72 warble-tone can be used in sound-field SAL testing with the warble-tone serving as the tonal stisulus. hopefully. this nethod would circusvent the occlusion effect problen nentioned above. The usefulness of sound- field SAL snploying spondee words has already been descnstratsd by Rintelnann and Johnson (1970). The warble-tone SAL studies should be perfcrned initially under earphones (conventional) and then in sound- field. Nornal hearing adult subjects should be tested first followed by pathological ears and then its feasibility should be investigated with children. In susnary. warble-tone audicsetry should prove to be a useful audiological tool for a variety of clinical applications. However. before this technique can becose a routine part of the audiologists' test battery. a series of studies nust first be conpleted. Sons of these basic investigations have been nentioned above. LIST 01" armc- LIST or RHEREJCE Allison laboratories. Inc.. The use of warble tone in clinical audiosetry. Bulletin _A_-§. IaHabra. Galifu Allison laboratories. Inc. (not dated). Aserican National Standards Institute. Inc.. herican National Standard Smification £93; Audio-store (ANSI 83.64%”. No"? r"'or'E." """' Aserican Standards Institute. Inc. (1969). Aserican Standards Association. Aserioan Standard Criteria for M Noise in Audio-star Rooas (ASA SBA-{$05. New York: Aserican Standards Association (1960). hrr. 3.. Pure tone audioaetry for pro-school children. Acta PM" 5‘1PP1. 121 (1955)- Beadle. 0.. and Graven. D. IL. Neonatal DIG responses to sound. g. mommy... 5. 112-123 (1962). Beltane Electronics Corp.. 222293.125 Instructions: Beltane H'r-um Harblg Tone Adafier. Chicago: Beltone Electronics Corp. H9611). Bender. 3.. A child's hearing: Part II Evaluation of a child's hearing. 5.122 minimal. 9.1.1591 2:29;. 3. h—7 (1967). Garhart. 3.. and Jerger. J. F.. Preferred aethod for clinical detsrain- a(tion)of pare-tone thresholds. g. m Hearing 214.. 2“. 330-316 1959 . Carver. H. F.. hjor Audiosetric Heasureaents. Chicago: Beltone Electronics Corp. 1 5 . Dallos. P.. and Tillnan. T.. The effects of paraaeter variations in Bekeey andioaetry in a patient with acoustic neurinoaa. g. £32531 £23322... 9. 557-572 (1966). IbVil. He. m Sfl'm. Se Re. R“: w MOSS (3rd 31.). NOW York: Holt. Rinehart a Winston g9??? ' ' DiGarlo. I... and Bradley. In. A sinplified auditory test for infants and young children. W. 71. 628-6146 (1961) Downs. I!" and Sterritt. G. 11.. A guide to newborn and infant hearing screening prograns. Arch. Mn 85. 15-22 (1967). 73 71. Fletcher. 3.. and Hunson. U. A.. Loudness. its definition. aeasureaent. and calculation. g. agonst. _So_<_:_. Aaer.. 5. 82-108 (1933). Furuktwa. 3.. Personal ccaaunications. Bion 60.. Ltd.. Tokyo. Japan 1970 . Gardner. H. 6. . A pulse-tone technique for clinical audiosotric aeasure- sonts. g. acoust. _S_os;_;. Assn. 19. 592-599 (19W). Glorig. A.. Screening techniques for the assessaent of hearing loss. Paper presented to the International Course in Redo-Audiology. The Netherlands (1953). Glorig. A.. and Hilke. 3. 3.. A new screening audio-star. J. acoust. as “Greg 2“. ‘‘50 (1952)e Hardy. J. B.. Dougherty. A.. and Hardy. H. 6.. Hearing responses and audiologic screening in infants. ,1. Pediat.. 55. 382-390 (1959). Hardy. H. 6.. The assessnent of auditory function. I. hearing in childreno-panol discussion. m. 68. 250 (1958). HC Electronics. Inc.. HG a} Phonic (% algfm Agioaeter. Tiburon. Califu 36 Electronics. Inc. 1 8 . Heron. T. 6.. and Jacobs. 3.. A physiological response of the neonate to auditory stinulstion. _In_1;. Audiol.. 7. 1.147 (1968). Heron. T. 6.. and Jacobs. 3.. hepiratory curve responses of the neonate t(.o auditory stisulation. _In_‘_l_:_. Audiol.. London Congress. 8. 77-81% 1969 . Hillis. J. 3.. and Dyer. H. J.. Success of play audiosotry as a function ~ of chronological age. Paper presented to the Annual Convention of Hood. J. D.. The principles and practice of bone conduction audio-etry. 231252-922. 70. 1211-1228 (1960). Jerger. J.. (31.). Modern Develogents .19. Audiology. 11.. York: Acadenic Press. illd (1933). Jerger. J.. and Tillnan. T.. A new aethod for the clinical dotsraination 2f sensorineural acuity level (SAL). Arch. 93M" 71. 998-955 1960 . Johnston. P. 3.. The lbssachusotts hearing test. .1. acoust. £03. Aaor.. 20. 697-703 (1918). Johnston. P. w.. An efficient group screening test. ,1. Smech 5293—155 214.. 17. 8-12 (1952). 75 langenbeok. B.. Textbook of Practical Audioaetgy. hltnore: The Liden. 6.. and Rankkunon. A.. Visual reinforce-out audiosetry in the unagaent of young deaf children. 323;. Audiol.. London Congress. 8. 99-106 (1969). ' Lybarger. S. F.. Interia bone conduction thresholds for audiosetry. lo gamma... 9. 1183-1587 (1966). hdsen mectronics. 611mg Audio-ator Model OB 60. Copenhagen. Den-ark: thsen Electronics. Mendel h. I. Infant responses to recorded sounds. g. Snech E3126 133.. 11: 811-816 (1968). “Jars. C. J.. “18. J. De. ‘1‘. raj-Ur. Es Peg m. ruibility or group audioaetry. Indust. Medicine. 17. 215-252 (19%). Heyerson. 1... Hearing for speech in children: A verbal audio-stric test. Am Me. Suppl. 128 (1956)e Miller. 3. 3.. and Polissr. I. A.. Audiologioal Evaluation of the It Pediatric Patient. Springfield: Charles 6. Thoaas. 29-30. 7 (1%). Miller. M. 3.. and hbinowits. 3.. Audiologioal probleas associated (1;: sre-natal rubella. _In_§. Audiol.. London Congress. 8. 90-98 1 9 . Newby H. Audiolgg (Rev. 31.). New York: Appleton-Gentry-m‘ofts has. 1 a ' Nielsen. S. F.. Group testing of school children by pure tone audiosetry. l- m we 21.9." 16. “-7 (1952). O'Neill. J. J.. M Oyer. H. J.. Aggied MIOIOtn. ROI York: Dodd. Head & Gas. ms (1%6)o Peck. J. 3.. The use of bottle-feeding during infant hearing testing. :1- M $9.25 21.9... 35. 3611-368 (1970). Roger. S. 3.. and Newby. 3.. A goup pure-tone hearing test. g. M 21_... 12. 61-66 (19117). Reilly. R. 3.. Frequency and aaplitude sodulation audiosetry. A.H.A. Me Me. 60. 363-366 (195&)e Reilly. R. 11.. The assossaent of auditory function. 1. Hearing in mildrenupanel discussion. W. 68. 250 (i958b). 76 Rintelaann. it. 3.. and Johnson. K. 3.. Coaparison of pure-tone versus speech sensorineural acuity level (SAL) test. Paper presented at the Annual Convention of ASHA. New York (1970). Schulaan. C. A.. and Fontana. V. J.. A clinical technique for the evaluation of hearing levels in infants. (In preparation). Cited in Misc Evoked Res nse Audion t . Canberra Industries. Inc.. Heriden. Conn. (1 9 . Siegel. 8.. Ron ric Statistics :21; 3h; Behavioral Sciences. Nev York: HcGraw-Hill 19 . Sivian. L. J.. and Shite. S. D.. Ch ainiaua audible sound fields. g. m. _S_9_c_. £35.. a, 288-321 (1933). 31th. C. 3.. Pediatric audiology. Maico Audiologioal gm Series. 6. 29-32 (1969). Staab. H. J.. and Rintelaann. H. F.. Status of warble-tone in audio-store. Unpublished (1971). Stevens. S. 8.. and lids. 3.. Heari_ng. It; Ps chol' a_r_1_d W. New York: John Wiley 8 Sons. Inc.. 235 (1938). Tracor. Inc.. Allison Model 22 Clinical and Research Audioaoter. Austin. Texas: Tracer. Inc. Tracer. Inc.. 153 Mose 3A 122 Harblet 2000 Infant Audioaoter. Austin. Texas: Traoor. Inc. Webster. J. 6.. A recorded warble tone audioaeter test suitable for group adsinistration over loudspeakers. g. wech Hearing lie... 17. 213-223 (1952)- wedenberg E. Auditory tests on newborn infants. Acts 93%. Stockholn. #6. #1164161 (1956). ' Young. I. 3.. and Barbert. 3.. Frequency aodulated tone thresholds in norsal and abnoraally adapting ears. Aug. Otol. Rhinol. 2525.. 79. 138-1“ (1970). APPHDICE APPHDIX A AMBIENT NOISE LEVELS IN TET 300M AMBIENT NOISE LEVELS IN TB! 300! Table A1 . Octave band and O-scale analyses of asbient noise levels in exaaination roo- (fan on) in dB SPL according to the standards set forth by the Aaerioan Standards Association (ABA 83.1- 1960 . Test Roo- - IAC 1200-ACT‘ Sound Level Meter - m 220'. Microphone - BAX #116 Octave had Filter Set - BAR 1613 Center Frequency in Rs O-Scale 31.5 63 125 250 500 1000 2000 M00 8000 dB SPL ‘55 311 M 26 <10 <10 <10 <10 <10 <10 APPHDIX B RATIONALE AND PROCEURE F03 CALIBRATION OF THE NARBLl-TONE SIGNAL RATIONALE AND PROCEDURES FOR CALIBRATION OF THE NARBLE-TONE SIGNAL calibration of Harble-Tone There are no accepted or consistent standards on which to base warble-tone calibration (Staab and Rintelaann. 1971 ). Since the sub- Jective loudness of a sound does not parallel its physical intensity. because of both intensity and frequency (Fletcher and Hunson. 1933). it would soon desirable to calibrate the warble-tone so that the loudness is constant in the total test frequency range. However. to do this would require that there be an understanding of the frequency deviations and sodulation rates necessary to equate the loudness at the various frequencies. Since this inforsation is not known. it see-ed desirable to calibrate the center or base frequency of the warble-tone through the ACCESSORY INPUT of the HA-Zh audioneter without any “warble” in a aanner sisilar to that advocated hy the Aaerican National Standards Institute (83.6-1969). The effect of this was that the sound pressure level (SPL) outputs obtained were not the ease as those for pure-tones because the ACCESSORY INPUT of the HA-Zh audio-ator was calibrated to a 19 dB SPL at '0“ V0. However. with the SPL output of the pure-tone and the center frequency of the signal to be warbled known. (after the input Hearing Threshold Level dial setting had been subtracted) it was a sinple latter to allow for the SPL.differences and sake appropriate coaparisons of the hearing thresholds obtained. This was done by 78 79 detersining the SPL outputs for '0' Hearing Threshold Level for both the warble- and pure-tones and adding or subtracting that value to the seasured Rearing Threshold Levels. This procedure can be used with any audioaeter as long as the SPL outputs and Hearing Threshold Level dial inputs are known for both the pure-tones and the center frequencies of the unaodulated warble-tones. Tables A3 and AN reflect the pre- and post-experiaent SPL outputs obtained for both the pure-tones and unaodulatod warble-tones. These values would nest likely change for other instrunentation. It was aandatory that the exact center frequencies. sodulation rates and frequency deviations utilised during the testing procedures be specified. The following indicates how this was done. Calibration of Center'grgguencz. This refers to the unaodulated center frequency obtained free the BAR 1013 beat-frequency oscillator. Since it was a sine wave the frequency counter (Bskaan Eput and Tiler. Model 61h8) was utilised to set the frequency by varying the FINE SCALE FREQUENCY ALIGNMENT of the beat-frequency oscillator until the frequency counter recorded the frequency desired. Calibration of Modulation Rate. An independent function generator (Hewlett-Packard Model 1033A) externally drove the beat-frequency oscillator to generate the various sodulation rates used. For exasple. if the function generator produced a 5 as signal. the sodulation rate was 5 per second. Consequently. the sodulation rates were easily detersined by reading a frequency counter connected to the output of the function generator. 80 Calibration of [fluency Deviation. Calibration of frequency deviation was perforned using a Tektronix Typo 3L5 Spoctrun Analyser Plug-in Unit designed for use with the Tektronix Type 56113 Model 12111 oscilloscope. The analyser displayed signal aaplitude as a function of frequency deviat ion and stability of aaplitude of the warble-tones. The basic procedure utilised in frequency deviation dotsrnination involved the sanipulation of a DISPESION knob on the Tektronix Type 3L5 Spectrua Analyser Plug-in Unit which allowed for the selection of a certain value of Hs/DIVision on the visual display area of the oscil- loscope. The value of the warble-tone frequency deviation desired at a given tine was aanually varied by nnipulating the FREQUENCY DEVIATION knob on the sex 1013 beat-frequency oscillator along with the output voltage of the external function generator until the display fell within the predeterained scale selected on the oscilloscope and outlined by the graticule divisions. Figure Ai gives an exaaple of a 310% frequency deviation at 1000 3s and Figure A2 shows a 110% frequency deviation at 8000 Rs. 81 ludivor 1 2003s DISPERSION . 5o Fin/DIV Frequency deviation - 200 Hz Figure A1. Visual display on an oscilloscope produced by a spectrua analyser showing a 110% frequency deviation centered around a base frequency of 1000 Rs. le—B div or 1600 113—4 DISPERSION . zoo ns/DIV Frequency deviation - 1600 Ha Figure A2. Visual display on an oscilloscope produced by a spectrua analyser showing a 110% frequency deviation centered around a base frequency of 8000 as. APPENDIX C LINEARITY OF NAICO HA924 AUDIONETER ATTENUATOR LINEARITY OF HAICO [AA-21$ AUDIONEI‘H ATTENUATOR A check of the linearity of the audioseter attenuator was porforsed acoustically with the test earphone attached to a BA! artificial ear and associated sound level aster and octave band filter set. while the ANSI-i969 Standard (83.6-1969) indicates that ”Measures for soapliance with this requireaent shall be aado electrically at the input to the earphone . . .." it was not possible with the systea utilised. to aeasure the electrical signals at low Roaring Threshold level settings because of the internal noise of the instruaentation. Consequently. a aodified version of checking audiosetor attenuator linearity was uti- lised which peraitted these seasuresents to be asde acoustically. The rationale and procedure for the technique follows : Rationale and Itocedure The reason for seasuring audioaeter attenuation is to ensure that changes in the Hearing Threshold Level dial result in cosparable sound pressure changes in the earphone. As long as these changes occur in a linear fashion (within given tolerances) throughout the entire range of the attenuator. it can be assuaod that the attenuator is functioning properly and in fact will result in appropriate sound pressure changes. Since the difficulties with noise usually encountered in asking these seasuresents acoustically (and in this experiaent also electrically). occur at aaxiaua attenuation. a probable solution appeared to be to 82 83 shift the SPL scale upward on the Hearing Threshold level dial. This was achieved by externally sending a 1000 Ha tone through the ACCESSORY INPUT of the audiometer. This input was calibrated to 19 dB for a “0" VU reading and consequently allowed for approxiaately an additional 20 dB range over which to test the linearity of the attenuator-even though the noise levels had not changed. This procedure is sisilar to that advocated for checking the Range and Intervals of Hearing Threshold Levels for Speech (ANSI 83.6-1969) except that the neasureaent is aade acoustically rather than electrically. In a good sound-treated rose (as was utilised in this experiaent) acoustical seasuresents down to approxiaately ~20 dB on the Hearing Threshold Level dial can be perforaed. The values recorded in Table A2 indicate that the Hearing Threshold Dial is linear down to -15 dB if the ANSI criterion is utilised (did not differ by aoro than 0.3 of the dial interval aeasured in dB). A by-product of this aodification is that at the upper end of the Roaring Threshold Level dial the aaxiaua power output of the audioaeter is reached at approxiaately 95 dB HTL. However. to check for linearity above this. seasuresents can be aade through the regular pure-tone system. In the current study thresholds were obtained in 2 dB steps by use of a six position VERNIER on the HA-zlb audioaeter which changes the Roaring Threshold Level output in 1 dB steps through a range of 5 dB. The audioaeter also allows for a -20 dB loss pad in series with the Hearing Threshold Level control. Although not shown in tabular fora. acoustical and electrical linearity checks of both of these con- trols indicated that they provided appropriate changes in sound pressure. Table Re 84 Pre- and post-experiaental linearity of Haico hAp24 audioaeter attenuator aade acoustically at the test earphone. dB HTL hrphone .. Right (TDH-39/1OZ) hrphene cushion .. 111-41 /AR Audioaeter - Haico HA-24 Artificial Ear - Ban! 4152 Andioaeter Channel - Right Sound Level Meter - BAR 2204 Microphone I M 4144 Octave End Filter Set - B&K 1613 Pro-experiaent Post-experiaent 1000 Rs 1000 as dB SPL dB dif dB SPL dB dif 115.4 115.7 110.7 4.7 111.1 4.6 105.8 4.9 106.1 5.0 101.0 4.8 101.4 4.7 95-9 5.1 96.2 5.2 91.1 4.8 91.4 4.8 86.0 5.1 86.4 5.0 81.2 4.8 81.6 4.8 76.1 5.1 76.4r 5.2 71.3 4.8 71.6 4.8 66.2 5.1 66.5 5.1 61.4 4.8 61.7 4.8 56.2 5.2 56.6 5.2 51.4 4.8 51.8 4.8 46.3 5.1 46.7 5.1 41.5 4.8 41.8 4.9 36.4 5.1 36.7 5.1 31.5 4.9 31.9 4.8 26.4 5.1 26.8 5.1 21.6 4.8 22.2 4.6 17.2 4.4 18.1 4.1 12.6 4.6 13.6 4.5 8.5 4.1 9.0 4.6 5.5 3.0 7.0 2.0 APPENDIX D EARPHONE OUTPUT DATA 85 .neaesoauss one: uHo>eH snore _¢Niea scavenpaaee Hashes. crass .«so\nochu «000.0 on core» one cHe>eH me enhances use escapeapdaeo Ha :0. as oedososuoum fleeces osovuodnnes nopeasuoass one no success 9mm on» meanneses.bn condense cues cashed scene .uoaaensessve no: one osovnodnnss on» you coveua seashoa soaceundade Hosanna one.-a .Nso\eonhc «000.0 on none» one cached m0 censuses can nnoaecnnaaee HaeA oneroonm .c 83833 833838 .89 ....H. . Hes 88...: .83 23a 88.38 or 8888.3 .888 8.91.8.8: 813888: 8c .388 E .9. 8. Teen 3.8.29 38m 8 or ... 88 889.38 80 no.3 3.838. 83.83 no 2. e. 8.6 838 .883 «are non .. in .3333. 33 can .. 8m 832 88 .580 .33 can .. 88983: «363:2. .. 25. .8883 8«« can ... 8...: 8.3 888 mi :18 a 25. .388 8.4: .3! .. 88838. A8386... 53 .8383 .3888 38382 838.: on» o» unannooos ones ones nuns-ensues: osoanensa one .nenescsaenh Henson «Ha-«an esov:ednnsn uoauasuosss one you censuses asmnso one Amy use .«Hnsuan esopionsm on» new censuses psnpso one Adv non none-onuse n~1<= onus: ona mo econnnso anwau on» new even pagans esonnnso Hove-cause use-«nemxolvuom .na canoe APPENDIX E HARMONIC DISTORTION DATA 88 Table A6 . Poet-experinentel hernonic distort ion noesurenente of the funduentel for test frequencies ueod.in the study. Measurements were node for the right earphone and right channel of the mica MIL-21$ nudioneter under two conditions: (1) that for the pure-tones generated by the Heioo HA-zh end (2) thot for the unmodulated warble-tone center frequencies through tho right channel and right earphone of the hico FLA-24 eudionetor. Measurements were node in compliance with the Anorioen National Standards Institute (ANSI 33.6-1969). Audio-eter . hico PIA-21} Microphone - w: MM mono Type - TDH-39/1OZ Artificial m- - m 4152 Cushion Typo - Hx-lll/AR Cathode Follower - m 2617 Frequency Anelyoer - M 2107 Hernonic Distortion Heeeurenente Condition #1 Frequency in H! 250 500 1000 2000 #000 8000 SPL of Mduentol 102.6 110.7 106.1 109.8 103.9 86.7 SPL with Mduental Bejeoted* 68.8 79.5 70.2 75.3 66.6 52.5 Dif- in dB 33-3 31-2 35-9 31*.5 37-3 3M2 Condition #2 SPL with Fundanental Rejected* 7M6 75.9 82.0 76.0 61.9 52.3 mt. in dB 38.5 39.8 33.6 36.6 143.9 03.0 fl'I‘heee values represent the total SPL remaining after the fundamental has been rejected. APPENDIX F RISE AND DMAY TIME DATA FOR AUDIOHEI‘EB INTERRUPI‘B 89 RISE AND DEA! TIME DATA FOR AUDIOHETER INTERRUPTEB Table A7. Pre- and post-experinental rise and decay tines as neasnred for pure-tones generated by the Maioo BIA-2h audiometer. The tines were neasnred tron the right channel of the audiometer with the assistance of a storage oscilloscope. Measurements were nade in con- pliance with the net-i... National Standards Institute (ANSI 33.6-1969). Andioneter .- Haico MA-zh Storage OscilloscOps - Tektronix Type 56hB Earphone Jack - Right Rise and Decay Tine Heasnrenents of the Tone Signals Pre—Erperinental Values Post-Experhental Values Mum” in H‘ Rise Tine" Decay Tine" Rise Tine" Decay Tire“ 250 M uses. '45 uses. ‘40 nsec. 50 nsec. 500 40 uses. 50 nsoc. 50 uses. #5 nsec. 1000 1&5 uses. #0 uses. 55 uses. 50 nsec. 2000 35 nsec. 50 uses. #5 uses. 1+5 nsec. M00 35 nose. 40 less. 50 uses. 50 noon. 8000 55 uses. 55 uses. 50 uses. 50 nsec. an 'Tine for SPL to rise Iron -20 dB to -1 dB re its final steady value. "Tine for SP1. to decay by 20 dB. APPHDIXG BONE- CDIDUCI'ION CALIBRATION DATA 90 eHo>55Heo « Nowell]. 5.55.. .5 .m u m. .8338... .5858 on. ... 5.... m. 5.3. .... . . . . . 8.88.... .m 56.. 56.. N6- .6- 56- n .5. ..5. u .5. 6 ..3 ~6~ 5.3 «.3 {mu 5.... m. 3825 .m 5.3 «.8 0.« e... .6... .5255. 5 ... 8.5 m. 88.... 6 2.. ~65 .... .62 5... .58... 5.55.. 5...... .5 a .... a ...m a. .... a. ... a: .mu .m 5 8882c a. .... 8. 6.8 6.3 6.. .... a. ma 8. a. .mu 8m 8 mm 3.5.... 8.88... 8.6 83.85.. 8.8.8888. 83 no. .- ..... .8885: «a: 5...: .85.. .. .... 5...... 5555.... ...... 8.5.6 .. 8...... .8. .... 5...: .85.. .. 5...... 55.5.... 8.... ...... .. 88.5... .Awmme .uonnanhqv hueooo«.n< you ouaonoouna noeeoeuoooaonom IduoenH Aodev oononoenoo hueoaunH can .5”... on. 3 8.5.... ...... one o. .58.... 8.8.... 3.. 85.85.. 8.8.8.8 6. .25 «Had :OHHiflmHndu IGHHUDQZOOAHQOQ APPWDIX H TET FREQUENCY m3 91 TEST FREQUENCY CHECKS Table A9. Pre- and post-experiaental frequency checks of the test frequencies of the Haico I'M-24 audioneter perforned in compliance with the herican National Standards Institute (ANSI s3.6-1969).* Audioneter - Maico PIA-21+ Voltneter - sex 2409 Channel - Right Frequency Counter - Eek-an 61% Pro-experiaent Frequency mocks Test y Measured ”an”; ”3;, we”? 2mg: 250 25“ +1! 1 .6% 500 503 +3 0.6“} 1000 1 006 +6 0.6% 2000 2008 +8 0.4% #000 #000 0 0.0% 8000 7998 -2 0.02% Post-experiaent Frequency (books 250 252 +2 0.8% 500 #99 -1 0.2% 1 000 1 003 +3 0.3% 2000 2006 +6 0.3% 4000 #001 +1 0.02% 8000 8002 +2 0.02% inn—W *The modulated warble-tone center frequencies were observed during all testing and were nanually varied so that they were within three percent of the indicated frequency. Rm METRIC]! ORDER FOB nun-rm STIHULI hble “0e 92 mm PRBENTATION ORDER FOR HARBLE-TONE STIMULI Randolised presentation order (P0) for the various cosbinations of warble-tone frequency deviations (PD) and sodulation rates (HR) for subject #1 for test session #1 . Center Frequency - 1000 Rs PO FD HR PO FD HR PO FD HR P0 FD HR 1. 3% film. 16. 10% 16/sec. 31. 6% 2/seo. 1+6. 10% 1/sec. 2. 50% fill». 17. 10% Mac. 32. 6% 16/sec. #7. 3% Rh». 3. 10% 2/seo. 18. 1% 32/sec. 33. 1% 1/sec. #8. 6% 32/sec. 4. 6% 16/sec. 19. 50% 1/seo. 3h. 3% 16/sec. b9. 1% 2/seo. 5. 6% 1/seo. 20. 3% Blue. 35. 3% 1/sec. 50. 501 We». 6. 6% 2/eec. 21. 1% 2/sec. 36. 1% 16/sec. 51. 6% 8/sec. 7. 10% Blue. 22. 50% Uses. 3?. 6% 1/seo. 52. 6% “Inc. 8. 10% blue. 23. 1% 32/sec. 38. 6% 32/seo. S3. 3% “less. 9. 1% Blue. 2t». 3% 32/800- 39. 10% Waco. 5h. 1% blue- 10. 10% 2/eec. 25. 1% blue. M. 1% 1/sec. 55. 3% 16/seo. 11. 6% It/sec. 26. ”10% :32/sec. #1. 10% 16/sec. 56. 3% Blue. 12. 101 32/3». 27. 11 Blue. 42. 50% blue. 57. 50% 32/2». 13. 50% 2/seo. 28. 6% Blue. #3. 50% Blue. 58. 130% Blue. 15. 50% 2/see. 29. 1% 16/sec. M. 50% We». 59. 3% 1/seo. 15. 3% 2/seo. 30. 50% 16/seo. #5. 3% 2/sec. 60. 50% 16/sec. Table “1e 93 hndonised presentation older (P0) for the various cosbinations of warble-tone frequency deviations (m) and sodulation rates (HR) for subject #1 for test session #2. Genterl'requuoy-zooom PO I'D IR P0 In HR PO an HR P0 In) HR 1. 50% “less. 16. 6% 16/seo. 31. 1% 2/sec. #6. 10% 2/see. 2. 1% blue. 17. 50% 32/see. 32. 10% blue. #7. 10% Blue. 3. 3% lt/see. 18. 10% Uses. 3. 50% blue. #8. 6% Was. ’h 1% Wm. 19. 50% 15h”. 3“. 50% Blue. 1’9. 6% “/006- 5. 10% 16k... 20. 1:: Glue. 35. 3x 32/see. so. 50% 16/sec. 6. 1% 1/see. 21. 6% Uses. 36. 10% Blue. 51. 3% Blue. 7. 3% Um. 22. 50% l/mo 37. 50% Zinc. 52. 3% 1/m. 8. 3% 2/sec. 23. 6% 32/seo. 38. 10% 32/sec. 53. 50% 2/seo. 9. 50% 32/see. 23. 1% Blue. 39. 6% 2/seo. 5“. 3% 32/sec. to. 6% 32/see. 25. 1% 16/sec. #0. 6% Uses. 55. 1% 32/sec. 11. 3% film. as. so: Blue. #1. 10% Isl-co 56. 1o: 2/sec. 12. 10% 32/seo. 27. 1% 32/see. #2. 1% 2/sec. 57. 3% Blue. 13. 50% ill». 28. 1% 16/sec. #3. 3% 16/see 58. 6% li/see. it. 1% 1/see. 29. 3% 2/sec. M. 6% 16/sec 59. 3% blue. 15. 6% Blue. 30. 10% 1/sec.} 1+5. 6% 2/sec 60. 10% 16/seo. Table A12. hndcnised presentation order (P0) for the various cosbinations of warble-tone frequency deviations (PD) and sodulat ion rates (HR) for subject #1 for test session #3. Center hequency - #000 a. P0 In) HR PO m HR PO FD HR P0 FD HR 1. 1% #lsec. 16. 3% 16/sec. 31. 1% 1/sec. #6. 50% 32/sec. 2. 6% 32/sec. 17. 6% z/sec. 32. 6% #lsec.L#7. 1% 32/sec. 3. 3% Uses. 18. 3% 1/sec. 33. 1% i6/see. #8. 1% Uses. #. 50% #/sec. 19. 50% 8/sec. 3“. 1% Blue. #9. 50% Blue. 5. 1% 2/sec. 20. 3% fill». 35. 6% 8/sec. 50. 6% 1/sec. 6. 101 32/seo. 21. as 8/sec. 36. 31 32k.” 51. 6% 32h... 7. 6% 2/seo. 22. 50% 32/800. 37. 10% “Inc 52. 10% 8/“0. 8. 10% 1/sec. 23. 50% Was. 38. 1% Blue 53. 10% 16/sec. 9. 6% Uses. 2#. 10% Blues. 39. 10% 16/sec 5#. 3%! 8/sec. 10. 3% 16/sec. 25. 50% 2/sec. #0. 3% #Im 55. 50% 1/see. 11. 6% “Inc. 26. 10% ”no. #1. 50% 16/seo 56. 3% 2/sec. 12.50% 1h... 27. 1% 2/sec. #2. 6% 16k... 57. 1% 16k... 13. 6% Blue. 28. 3% 2/see3 #3. 50% 16/see 58. 1% #/sec. 1#. 50% 2/sec. 29. 6% Wm. ##. 3% #Im 59. 10% #/seo. 15. 10% 32/see. 30. 1% 32/sec. #5. 10% 2/... 60. 10% 2/seo. Tau. “3e rates (HR) for subject #1 for test session It. 95 hudcsised presentation order (P0) for the various cosbinations ef warble-tone frequency deviations (PD) and sodulation Center Frequency .- 8000 [is PO FD HR PO FD HR P0 I'D HR P0 FD IR 1. 1% 16/sec. 16. 10% 32/sec. 31. 50% 16/sec. #6. 1% 32/sec. 2. 1% 2/sec. 17. 3% 16h». 32. 1% 32h“. #7. 10% 32h». 3. 3% 1/sec. 18. 10% #/m. 33. 6% 1/sec. #8. 6% 32/000. #. 6% 32/sec. 19. 6% #/sec. 3#. 1% 2/sec. #9. 3% 2/sec. 5. 10% 16/sec. 20. 3% 16/seo. 35. 10% 1/sec. 50. 50% 32/sec. 6. 10% Was. 21. 1% Blue. 36. 6% 16/sec. 51. 10% 16/sec. 7. 1% Us». 22. 10% Blue. 37. 3% #/seo. 52. 50% “[800. 8. 50% 1/sec. 23. 50% 8/sec. 38. 50% #/m. 53. 50% 8/ses. 9. 10% 1/sec. 2#. 3% #/sec. 39. 1% Bk». 5#. 3% 2/sec. 10. 6% 1/sec. 25. 3% 32/sec. #0. 6% 2/sec. 55. 3% Blue. 11. 50% 2/seo. 26. 10% 2/sec. #1. 6% 8/sec. 56. 3% 32/sec. 12. 50% 2/see. 27. 50% 16/sec. #2. 1% #/m. 57. 6% 16/sec. 13. 10% 2/sec. 28. 6% #/sec. #3. 6% 2/sec. 58. 50% Has. 1#. 1% #/see. 29. 1% 16/sec. ##. 50% 32/sec. 59. 3% 1/sec. 15. 6% 8/seo. 30. 3% 8/sec. #5. 10% #/sec. 60. 1% 1/sec. Table A1#. 96 hndcsised presentation order (P0) for the various cosbinations of warble-tone frequency deviat ions (PD) and sodulat ion ratetOlR) for subject #1 for test session #5. Center Frequency - 500 Rs PO FD HR PO FD HR PO FD HR PO FD HR 1. 1% 32/eee. 16. 10% 1/sec. 31. 6% 6/sec. #6. 6% 32/sec. 2. 50% 32/sec. 17. 3% Wm. 32. 3% Wm. #7. 10% 16/sec. 3. 10% #/sec. 18. 1% 2/sec. 33. 6% #/sec. #8. 50% i/sec. #. 3% 16/sec. 19. 3% 16/sec. 3#. 50% 32/sec. #9. 3% Uses. 5. 6% Blue. 20. 3% Wm. 35. 1% 16/sec 50. 6% Uses. 3 6. 6% #/sec. 21. 50% 16/sec. 36. 6% 8/sec 51. 50% 2/sec. 7. 6% 32./.... 22. 3% 32k». 37. 10% 41/... 52. 101 an... 8. 50% #/sec. 23. 50% #/sec. 38. 1% #/sec 53. 6% 2/sec. 9. 10% 32/sec. 2#. 1% Blue. 39. 3% 2/sec 5“. 50% 2/sec. 10. 50% 16h». 25. 6% 1/see. #0. 10% 2/sec 55. 3% 1/sec. 11. 1oz 32/sec. 26. 10% 1/....u1. 3% 32m. 56. 10% an... 12. 1% 1/sec. 27. 1% 16/sec. #2. 6% 16/sec 57. 6% 2/sec. 13. 50% 8/see. 28. 10% 16/sec. #3. 1% 8/sec 58. 10% Z/sec. 1#. 1% #/see. 29. 50% 1/sec. ##. 3% 8/sec 59. 50% Was. 15. 1% 2/sec. 30. 1% 32/sec. #5. 3% 8/sec 60. 1% Uses. __..J= h.__ Table A15. 97 Bands-ised presentation order (P0) for the various cosbinations of warble-tone frequency deviations (FD) and sodulation rates (HR) for subject #1 for test session.#6. Center Frequency - 250 as PO 1. 2. 3. 6% 1% 1% u. 50% 5. 16% 6. 10% 7. 1% a. 10% 9. 50% 1o. 1% 11. 10% 12. 1% 13. 6% lb. 10% 15. 6% 1/see. 1/seo. 32h»- 2/eeo. 2/seo. 16/sec. z/.... 32/sec. 8/sec. 32/seo. i/sec. 8/sec. 2/eee. 1/sec. 16/me 16. 17. 18. 19. 20. 22. 23. 25. 26. 27. 28. 29. 30. 1% 10% 6% 50% 3% 10% 10% 50% 6% 50% 3% 10% 50% 1% 2/sec. 2/sec. #Iseo. 16/sec. #/sec. #/eec. 8/seo. #7.... 1/sec. 16/see. 17.... i/seo. 32/sec. Z/sec. h/“Ce 31. 32. 33. 3*. 35. 36. 37. 38. 39. #0. #1. #2. #3. #5. 1%; 13% 10% 6% 50% 3% 50% 10% 6% 50% 3% 10% 1 10% 3% 16/sec. 32h»- 8/seo. 8/eec. 8/seo. a/.... 16/seo. z/b... 8/eec. 32/sec. 16/sec. #Isec. 8/sec. 16/sec. Z/Me 51. 53. 1%; 3% 3% 6% 50% 1% 1% 10% 6% 6% 50% 3% 50% 6% i/seo. z/eec. 8/eec. 32/5... 1/seo. #leec. i6/seo. 16/sec. 32h... #/sec. 32/sec. 32/5... 1/sec. #/eec. 1/800e T‘hl. ‘16s rates (HR) for subject #2 for test session 0‘1. 98 Randonised presentation order (P0) for the various cosbinations of warble-tone frequency deviat ions (FD) and sodulat ion P0 Center Frequency - 1000 Es PD POFD HR 1 . 50% 10% 6% 6% 1% 1% 2. 3. #. 5. 6. 7. 8. 9. 10. 6% 6% 10% 10% 12. 6% 13. 6% 1#. 50% 15. 3% 11. Z/bOOe 32h»- 2/sec. 1".ce n/IOce 2/see. 3‘; 16/I00e 16/‘00e 2/sec. 2/sec. 8/sec. 8/seo. #/sec . 16/I00e 8".0e 16. 17. 18. 19. 20. 21. 22. 3% 50% 3% 1% 10% 3% 6% 3% 10% 50% 10% 3% 1% 10% 1% llbOOe 2,..Ce 32,3.Ce 32/IOOe 2/COCe 8/IOCe “/ICOe ~/'O°e i6/sec #/seo. #/sec. #/secJ #/sec. 316/COCe l/bOGe 3% 3% 50% 6% 3% 10% 50% 1% 6% 6% 31 . 32. 33. 34. 35. 36. 37. 38. 39. #0. 1/‘00e Z/hOCe 32/sec. 32/eec. 16/seo. 32/see. 1,..oe 1,8..e a/IOCe 16/‘03e his 50‘: 32,8060 #2. 10% #3. 50% ##. 1% #5. 6% 1/..°e 16/300e 8".0e l/IOce 50. 51 . 52. 53. 5‘}. 55. 56. 57. 58. 59. 50% 6% 1% 1% 50% 1% 1% 3% 10% 1% 10% 50% 50% 3% 60. 10% 1/sec. 32,..Oe 8/sec. 16/800e B/IOCe 32,..Ce lé/bOCe 2/sec. 1/sec. 2/sec . #/sec. #lsec. a/IOCe 32l800e a/UOQe =1 Table M7e 99 Handonised presentation order (P0) for the various cosbinations of warble-tone frequency deviations (FD) and sodulation rates (HR) for subject #2 for test session #2. . M PO Center Frequency - 2000 HI ID HR P0 FD HR PO ED 1. 2. 3. #. 5. 6. 7. 8. 9. 10. 11. 12. 13. 1#. 15. ”7 1% 1% 6% 10% 10% 1% 50% 10% 6% 50% 50% 10% 1% 6% 16. 17. 18. 19. 20. 21 . 22. 23. 2#. 25. 26. 27. 28. ‘ 29. 3°- 10, 32/800. 310 50% 16,.”0 3% 116/800. 32. 1% 32/800. 10% “/0000 33. 6% 1/800. 6% #Isec 3#. 1% 2/seo 3% 15/806 35. 10% 1/sec 1% Blue 36. 6% 16/sec 10% 8/seo 37. 3% #/sec 50% Blue 38. 50% #/see 3% #/sec 39. 1% 81sec 3% 393/000 #0. 6% 2/sec 10% 2/sec #1. 6% Blue 50% 16/seo #2. 1% #/sec 6% #/m 53. 6% 2/seo 1% 16/sec 5#. 50% 32/sec 3% Wm 55. 10% #/sec #6. 1% #7. 10% #8. 6% #9. 3% 50. 50% 51. 10% 52. 50% 53. 50% 5“. 3% 55. 3% 56. 3% 57. 6% 58. 50% 59. 3% 60. 1% f 32/sec. 32/800- 32/«0- 2/sec. 32/eeo. 16/seo. #/sec. 8/sec. 2/seo. 8/sec. z/a... 16/sec. 1/sec. . 1/seo. 1/‘00e 100 Table M8. mndonised presentation order (P0) for the various conbinations of warble-tone frequency deviations (PD) and sodulation rates. (n) for subject #2 for test session 33. Center hequency :- #000 Rs PO FD HR PO FD HR P0 FD HR PO FD HR 1. 6% Moss. 16. 1% Uses. 31. 1% 32/sec. #6. 10% #/sec. 2. 10% 8/sec. 17. 6% 16/sec. 32. 6% #/sec. #7. 50% 16/sec. 3. 10% Blue. 18. 1% 2/sec. 33. 6% 32/sec. #8. 10% 1/eec. #. 3% i-2/sec. 19. 1% Uses. 3#. 3% 8/sec. #9. 50% 2/sec. 5. 50% 8/800. 20. 6% 1/000. 35. 1% #Isec. 50. 1% 8/Ieo. 6. 6% 2/sec. 21. 3% 8/seo. 36. 6% 32/sec. 51. 3% 16/seo. 7. 1% 16/sec. 22. 50% Blue. 37. 1% 8/sec. 52. 50% #/sec. 8. 1% Uses. 23. 3% ill». 38. 3% #/sec. 53. 50% 16/sec. 9. 6% 8/sec. 2#. 3% #/sec. 39. 6% 2/seo. 9!. 1% 16/see. 10. 1% 32/sec. 25. 10% #/sec. #0. 10% 1/sec. 55. 1% #/sec. 11. 10% 32/sec. 26. 3% 32/seo. #1. 10% 2/seo. 56. 3% Uses. 12. 6% Blue. 27. 3% 16/sec. #2. 50% 1/sec. 57. 50% 2/sec. 13. 10% “has. 28. 3% 2/sec. #3. 10% 32./sec. 58. 6% 16/sec. 1#. 50% Rb». 29. 6% #lsec. ##. 10% 16/sec. 59. 50% 1/seo. 15. 50% #/see. 30. 50% 32/seo. #5. 3% 32/sec. 60. 10% 2/sec. 101 Table A19. Bands-ind presentation order (P0) for the various cosbinations of warble-tone frequency deviations (FD) and sodulation rates (HR) for subject #2 for test session I". W! Centerh'equeney-8000Hs POFD HR P0 FD HR POPD MB POFD HR 1. 6% Uses. 16. 1% 2/sec. 31. 1% 16/sec. #6. 1% Von. 2. 1% VI». 17. 10% Hose. 32. 3% 32/sec. #7. 3% 2/sec. 3. 1% 32/sec. 18. 6% Wm. 33. 10% 8/sec. #8. 3% Blue. #. 50% 2/sec. 19. 50% 16/sec. 3". 6% 8/sec. #9. 6% Rh». 5. 6% 2/sec. 20. 3% #/sec. 35. 50% Blue. 50. 50% 1/«c. 6. 10% 16/seo. 21. 10% #/seo 36. 3% 8/sec. 51. 1% #/seo. 7. 1% 2/sec. 22. 10% Blue. 37. 50% 16/sec. 52. 1% Mk». 8. 10% 32/000. 23. 3% #/m 38. 10% 2/800. 53. 10% 16/se0. 9. 50% 8/sec. 2#. 50% 1/sec. 39. 3% 16/seo. 5#. 6% RIM. 10. 1% 32/see. 25. 6% 16/sec. #0. 6% 8/seo. 55. 6% #/sec. 11. 10% 1/see. 26. 50% #lsecfi #1. 50% 32/sec. 56. 50% 32/see. 12. 1% 8/sec. 27. 3% Mac. #2. 10% Wm. 57. 3% 32/sec. 13. 6% 2/see. 28. 10% 32/seo. #3. 1% Wm. 58. 3% Uses. 1#. 10% U“. 29. 50% 2/800. ##. 3% 16/“0. 59. 50% “/0”. 15. 6‘ 16/“0e 30s 1‘ I"/CCCe “Se 3% 2/“0e 60e 6‘ 1/‘00e W T‘bl. ‘20s 102 nandcniaed presentation order (P0) for the various cosbinations of warble-tone frequency deviations (FD) and nodulaticn rates (HR) for subject #2 for test session #5. Centerhnquency-SOOHI FD HR PO FD P0 FD 1 . 1% 6% 3% 50% 1% 10% 6% 10% 6% 3% 6% 2. 3. 4. 5. 6. 7. a. 9. 1o. 11. 12.50% 13. 6% 1#. 50% 15. 10% #/sec. Sal-oe- 1/sec. #/sec. 2/sec. 32/sec. 2/sec. i/sec. i/sec. 16/ses. 16/see. 1/sec. 8/sec . 2/eec. 32h»- 3% 16/seo. 6% 3% 50% 2/sec. i/see. 8/sec. 32h»- Blue. 32/sec. #/sec. 8/sec. Z/sec. 2/sec3 2/sec4 2/sec #/sec 1% 32/sec 31 . 32. 33. 3“. 35. 36. 37. 38. 39. #0. #1 . #2. #3. ##. #5. 1% 6% 1% 1% 6% 3% 10% 1% 10% 3% 50% 6% 50% 3% 10% 1/sec. #/sec. 16/sec. Blue. Blue. 32h»- #/sec. 8/seo. 16/sec. #/seo. 16/seo. 16/sec. 16/sec. #/sec. Z/BOOe #6. 50% #7. 1% 1% 50% 6% 6% 10% 10% 3% 50% 3% 1% 1% 10% 10% #9. 50. 51 . 53. 5#. 55. 57. 58. 59. 60. 32h»- 32h». 1/sec. 8/sec. 1/sec. 32/.... 8/seo. 16/seo. 8/sec. 1/seo. 2/sec. 16/sec. #/seo. #/sec. 2/sec. PO Table ‘21s PD 103 iandcnissd presentation order (P0):for the various cosbinations of warble-tone frequency deviations (FD) and sodulation rates (HR) for subject #2 for test session #6. PO Center Frequency - 250 HI ID PO FD PO FD PM 1. 2. 3. #. 5. 6. 7. 8. 9. 10. 11. 12. 13. 1#. 1%: 6% 3% 50% 1%; 10% 6% 10% 6% 3% 6% 50% 6% 50% #Iseo. 32/seo. 1/sec. #leee. z/seo. 32/eec. 2/.... 1/sec. 1/see. 16/sec. 16/sec. i/seo. e/t... 2/“0e 16. 17. 18. 19. 20. 21. 22. 23. 2#. 25. 27. 28. 29. 3‘ 16/000. 6% 3% 50% 3% 3% 50% 50% 10% 50% 10% 1% 6% 2/seo. 1/seo. 8/seo. 32h». Blue. 35. 36. 32/500.137. t/IOCe 8/seo. 2/“Oe 38. 39. 1% 6% 1% 1% 6% 3% 10% 1% 10% 3% 2/sec. 2/eee. “/me 6% 50% 3% 1/eec. #jsec. 16/sec. 8/seo. 8/seo. 32/000- #lseo. 8/seo. 16/seo. #6. #7. “/seo.H55. 16,..Ce 16’Me 16/seo. 56. 57. 58. 59. 50% 1% 1% 50% 6% 6% 10% 10% 3% 50% 3% 1% 1% 10% 32h». 32/seo. 1/seo. 8/see. 1/090. 32/sec. 8/seo. 16/seo. a/.... 1/sec. 2/see. 16/sec. #lseo. ‘/”¢e 10# Table A22. hndosised presentation order (P0) for the various cosbinat ions of warble-tone frequency deviations (PD) and sodulation rates (HR) for subject #3 for test session #1. Center Frequency - 1000 He PO PD HR PO FD HR PO FD HR PO FD HR 1. 1% film. 16. 10% 32/sec. 31. 50% 16/sec. #6. 1% 32/sec. 2. 1% 2/sec. 17. 3% 16/sec. 32. 1% 32/sec. #7. 10% 32/seo. 3. 3% Uses. 18. 10% #/sec. 33. 6% 1/sec. #8. 6% 32/sec. #. 6% 32/seo. 19. 6% #/sec. 34. 1% 2/sec. 49. 3% 2/sec. 5. 10% 16/sec. 20. 3% 16/sec. 35. 10% 1/seo. 50. 50% 32/sec. 6. 10% Wow. 21. 1% 8/sec. 36. 6% 16/sec. 51. 10% 16/sec. 7. 1% Uses. 22. 10% Blue. 37. 3% #/sec. 52. 50% #/seo. 8. 50% 1/.... 23. 50% ‘ 8/sec. 38. 50% up... 53. 50% 85.... 9. 10% Uses. 2#. 3% #/sec. 39. 1% Blue. 5#. 3% 2/sec. 10. 6% 1/sec. 25. 3% 32/seo. #0. 6% 2/sec.155. 3% 8/sec. 11. 50% 2/sec. 26. 10% 2/seo. #1. 6% 8/sec. 56. 3% 32/sec. 12. 50% Z/sec. 2?. 50% 16/sec. #2. 1% #/sec. 57. 6% 16/sec. 13. 10% 2/sec. 28. 6% #/sec. #3. 6% 2/secJ 58. 50% 1/3... 1#. 1% #/sec. 29. 1% 16/sec. ##. 50% 32/sec 59. 3% 1/sec. 15. 6% 8/sec 30. 3% 8/sec. #5. 10% #/secl60. 1% Uses. 1101. A23. cosbinations of warble-tone frequency deviations (PD) and sodulation rates (HR) for subject #3 for test session #2. —_._—.__m PO 105 Center Frequency - 2000 as FD P0 FD Randonised presentation order (PO) for the various 1. 2. 3. #. 5. 6. 7. 8. 9. 10. 11. 12. 13. 1#. 15. 6%; 1% 1% 50% 6%: 10%: 1% 10% 50% 1% 10% 1% 6% 10% 6% 1/sec. 1/eeo. 32/seo. 2/see. 2/eec. 16/eeo. 2/sec. 32/mo 8/sec. Balm- 1/seo. 8/eeo. 2/see. 1/eeo. 16/Me 16. 17. 18. 19. 20. 21 . 22. 23. 2b. 25. 26. 27. 28. 29. 30. 1% 10% 6% 50% 3% 10% 10% 3% 50% 6% 50% 3% 10% 50% 1% _: 2/seo. 2/eec. #Isec. 16/sec. #/sec. #lseo. 8/sec. #/sec. i/sec. 16/seo. #/sec. 1/seo. 32/seo. 2/see. ‘/“¢e 1% 3% 10% 6% 50% 3% 50% 10% 3% 6% #1. 50% #2. 10% #3. 1% #4. 3% #5. 3% 35. 37. 38. 39. 16/seo. 32/sec. 8/sec. 8/sec. 8/sec. 8/sec. 16/sec. 2/sec. 16/sec. 8/sec. 32h»- #/sec. B/seo. 16/seo. 2,..Oe _ 1%: 3% 3% 6% 50% 1%: 1% 10% 6%: 6% 50% 57. I%‘ 58. 3% 59. 50% 60. 6% 55. 56. 1/sec. 2/sec. 8/sec. 32/sec. i/sec. #/sec. 16/sec. 16/eec. 32/sec. #lsec. 32/seo. 32/sec. 1/sec. #/seo. 1/“0e 106 an. A211. Randomized presentation order (PO) for the urioue cabinetim e! warble-ten frequency devint1ene (PD) and eeduhtion retee (HR) for eubjeet #3 for test session #3. Centerhequem-MOOHI PO FD EB PO I'D HR IPO I'D IR PO PD HR 1. 50% Z/eeo. 16. 3% 1/eec 31. 3% Used. #6. 50% 1/eeo. 2. 10% 32/m. 17. 50% 2/eeo 32. 3% 2/.... 1&7. 6% 32b». 3. 6% 2/eee. 18. 3% film 33. 50% 32/eec. #8. 1% Blue. '0. 6% 1/eec. 19. 1% 32/m 3“. 6% 32/eeo. I“9. 1% 16/000. 5. 1% Wm. 20. 10% 2/eec 35. 3% 16/eee. 50. 50% Bleec. 6. 1% 2/eeo. 21. 3% Blue 36. 10% film. 51. 1% 32/eee. 7. 3% 16/800. 22. 6% film 37. 50% 1/lec. 52. 1% 16/lec. 8. 6% 16/eeo. 23. 3% We» 38. 1% Used. 53. 3% Z/eeo. 9. 6% 2/eee. 2b. 10% 16h» 39. 6% Blue. 5“. 10% 1/eee. 10. 10% 2/eee. 25. 50% blue #0. 6% 16/eee. 55. 1% Z/eec. 11. 10% Wm. 26. 10% h/eec #1. 50% 32/eec 56. 10% VI». 12. 6% Blue. 27. 3% Ween #2. 10% Used 57. 50% #lm. 13. 6% blue. 28. 1% 4/eec ‘13. 50% 16/eec 58. 50% Blue. 1#. 50% 16/eee. 29. 10% 16/eec Ml. 1% '8/eec 59. 3% 32/eec. 15. 3% Blue. 30. 1% 1/eeo #5. 6% 1/eec 60. 10% 8/eec. Teble A25. 107 hndoeieed preeentetion order (PO) for the verione coebinet icon of urble-tone frequency devietione (FD) end eodnlet ion retee (HR) for subject #3 for teet eeeeion #1. Center Frequency - 8000 He PO FD HR PO FD HR PO I'D HR PO FD HR 1. 1% film. 16. 10% 1/eeo. 31. 6% 16/eeo. #6. 6% 32/eeo. 2. 50% 32/300. 17. 3% b/eeo. 32. 3% Ween. 47. 10% 16].“. 3. 10% kleec. 18. 1% 2/eec. 33. 6% b/eec. #8. 50% 1/eeo. it. 3% 16/eeo. 19. 3% 16/806. 3“. 50% 32/m. ’19. 3% ill”. 5. 6% Blue. 20. 3% 2/oeo. 35. 1% 16/eeo. 50. 6% 1/eoc. 6. 6% 4/eec. 21. 50% 16/eec. 36. 6% Shoe. 51. 50% 2/806. 7. 6% 32/Ieo. 22. 3% 32/Iec. 37. 10% h/eec. 52. 10% Blue. 8. 50% lt/eec. 23. 50% blue. 38. 1% h/eec. 53. 6% 2/eeo. 9. 10% 32/eeo. 21!. 1% 8/eec. 39. 3% 2/eeo+5h. 50% 2/eec. 10. 50% 16/eeo. 25. 6% 1/eeo. #0. 10% 2/eec. 55. 3% 1/eec. 11. 10% 32/eeo. 26. 19% 1/eeo. 41. 3% 32/eec. 56. 10% 8/eec. 12. 1a: m... 27. 1x 16/.... #2. 6% 16/eec.” 57. ex ‘21.... 13. 50% Bleec. 28. 10% 16/eeo. §3. 1% Blue. 58. 10% 2/eeo. 1h. 1% b/eec. 29. 50% 1/eec. Ni. 3% 8/eeo. 59. 50% Blue. 15. 1% 2/eec. 30. 1% 32/eeo. #5. 3% 8/eee160. 1% 1/eeo. 108 Teble A26. hndoeized preeentetion order (PC) for the verioue coebinet ione ed’ werble-tene frequency devietione (no) end nodulet ion retee (HR) for eubjeot #3 for teet eeeeion #5. Center Frequency :- 500 He POPD HRPOFD HRPOFD HRPOFD HR 1. 6% 1/eec. 16. 1% 1/eeo. 31. 1% 32/eeo. #6. 10% #leeo. 2. 10% 8/eeo. 17. 6% 16/eeo. 32. 6% #leec. #7. 50% 16/eeo. 3. 10% Blue. 18. 1% Z/eeo. 33. 6% 32/eec. #8. 10% 1h». #. 3% z/eee. 19. 1% 2/eeo. 3#. 3% 8/eec. #9. 50% Z/eeo. 5. 50% Blue 20. 6% 1/eeo. 35. 1% Mac. 50. 1% 8/eeo. 6. 6% Z/eeo 21. 3% Blue. 36. 6% 32/eeo. 51. 3% 16/eec. 7. 1s 16/... 22. 50% 8/.... 37. 1% 8/eeo. 52. 50% #/eeo. 8. 1% Us». 23. 3% 1/eeo. 38. 3% #/eeo. 53. 50% 16/eec. 9. 6% Blue. 2#. 3% #/m. 39. 6% Z/eeo. 5“. 1% 16/eeo. 10. 1% 32/neo 25. 10% #/eeo. #0. 10% 1/sec. 55. 1% #[eec. 11. 101 32/... 26. 3:: 32A... #1. 10% Z/eeo. 56. 3% Mac. 12. 6% Blue. 27. 3% 16/eec. #2. 50% 1/eec. 57. 50% L'Z/BOC. 13. 10% 16/eeo 28. 3% 2/eec. #3. 10% 32/eeo. 58. 6% 16/eec. 1#. 50% film 29. 6% #/eeo. ##. 10% 16/eeo. 59. 50% 1/eeo. 15. 50% #/eec 30. 50% 32/nec. #5. 3% 32/aec. 60. 10% Z/eec. 109 Table A27. Rendoeized preeentetion order (PC) for the verioue coebinetione of uerble-tone frequency deviations (PD) and eoduletiou retee (HR) for subject #3 for test eeeeion #6. N Center Frequency - 250 He PO FD HR P0 FD MR P0 FD HR P0 FD HR 1. 1% #/eec. 16. 3% 16/eec. 31. 1% 1/eeo. #6. 50% 32/eeo. 2. 6% 32/eec. 17. 6% 2/eec. 32.’ 6% #leec. #7. 1% 32/eec. 3. 3% 1/eec. 18. 3% 1h». 33. 1% 16/eec. #8. 1% 1/eec. #. 50% #/eeo. 19. 50% 8/eec. 3#. 1% 8/eec. #9. 50% 8/eec. 5. 1% 2/eec. 20. 3% 32/eec. 35. 6% Blue. 50. 6% Mac. 6. 10% 32/eec. 21. 3% Blue. 36. 3% 32/eeo. 51. 6% 32/eec. 7. 6% 2/800. 22. 50% 32/eec. 37. 10% #/eec. 52. 10% Blue. 8. 10% 1/eec. 23. 50% #/m. 38. 1% 8/eec. 53. 10% 16/eec. 9. 6% 1/eeo. 2#. 10% 8/eec 39. 10% 16/eec. 5#. 3% Blue. 10. 3% 16/eec. 25. 50% Z/Iec] #0. 3% Moon] 55. 50% 1/eec. 11. 6% 16/eec.. 26. 10% 1/eec. #1. 50% 16/eec. 56. 3% 2/eec. 12. 50% 1/eec. 27. 1% 2/eec. #2. 6% 16/eec. 57. 1% 16/eec. 13. 6% Blue. 28. 3% 2/eecw #3. 50% 16/eeo. 58. 1% #/eec. 1#. 50% 2/cec. 29. 6% #/m. ##. 3% #/eec. 59. 10% #/eec. 15. 10% 32./see] 30. 1% 32/eec. #5. 10% 2/eec.‘ 60. 10% Z/eec. an W DIVIATIONS FOR I“!!! rm mm (II m man All) 112) ALOIG Wm READINGS MUM 0!! m INSTRUMATION UTILIZD T0 PRODUCE AID mm m "MID-TONI STIHULI 110 FEMUE‘NCY DEVIATIONS FOR EACH TET MUMCY (IN BOTH PERCENT AND HZ) ALONG WITH REKDINGS REQUIRED ON THE INSTRUMENTNTION UTILIZED TO PBODUCE AND HIISURE‘THE HARBLEeTONE STIMULI Teble 128. The rannunncr DENINTION (FD) setting required on the heet- uency oscillator, along with the VOLT SCALE (V8) and OUTPUT VOLTAGE v) on the function generator. and the Hz/DIV (H/D) setting of the storage scope spectrue analyzer to produce and nonsure the warble- tone frequency deviations given.* Center Frequency - 250 H! Percent Frequency 11% 13% 16% '31 0% 150% Devietion Frequency Deviation 5 15 30 50 250 in Hz Instrument Dial Setting Required no $100 1100 £100 £100 £250 VS 1 1 3 3 1 0 V 0.25 0.5 1.1 1.6 #.O *The noduletion rates used in this study had no effect on any of the eeesured frequency devietions and consequently are not shown in the table. 111 Table 129. The FREQUENCY DEVIATION (FD) setting uired on the beat-frequency oscillator, along with the VOLT SCALE (:3 and OUTPUT VOLTAGE (v) on the function generator, and the Hs/DIV (H/D) setting of the storage scope spectrus analyser to produce and eeasure the warble- tone frequency deviations given.‘ Center Frequency I 500 H! Percent . Frequency 1‘1 % 33% 16% 1'1 0% 150% Deviation Frequency Deviation 1 0 30 60 1 00 500 in Hz Instrusent Dial Setting Required FD 1100 1100 :100 1100 than '8 1 3 3 3 20 V 0.# 1 .0 1 .9 2 .8 4. 0 H/D 10 10 10 20 100 *‘l‘he sodulation rates used in this study had no effect on any of the measured frequency deviations and consequently are not shown in the thIOe 112 Table A30. The moms! DEVIATION (FD) setting uired on the beat-frequency oscillator, along with the VOLT SCALE (:3 and ovmr VOLTAGE (v) on the function generator, and th. Ila/DIV (Ii/D) setting of the storage scope spectrus analyser to produce and eeasure the warble- tone frequency deviations given.* m Center Frequency .- 1 000 Rs Percent Frequency 11% 13% 16% “310% ~ 150% Deviation Frequenoy Deviation 20 60 120 200 1000 in as Instruent Dial Setting Required m 2:100 $100 1100 $160 1630 V8 1 3 10 10 10 V 0.78 1.7 3.# 4.2 4.2 H/D 10 50 50 50 100 in“ *The sodulation rates used in this study had no effect on any of the seasured frequency deviations and consequently are not shown in the table. 113 Table A31. The FREQUENCY DEVIATION (FD) setting re uired on the beat-frequency oscillator, along with the VOLT SCALE (VS and OUTPUT VOLTAGE (v) on the function generator, end the Hz/DIV (H/D) setting of the storage scope spectrum analyzer to produce and secure the warble- tone frequency deviations given.* Center Frequency - 2000 Hz Percent Frequency 11% 33% 16% 1‘1 0% 350% Deviation Frequency Deviation in H! #0 120 2#0 #00 2000 Ihstrueent Dial Setting Required FD $100 1100 1160 tooo 11000 V8 3 10 10 10 10 V 1 s 3 3 a“ “.8 3 .2 no 0 H/n 20 5o 50 100 200 *The nodulation rates used in this study had no effect on any of the seasured frequency deviations and consequently are not shown in the table e 11# Table A32. The Emmet DEVIATION (FD) setting uired on the heat-frequency oscillator. along with the .VOLT SCALE (:3 and OUTPUT VOLTAGE (V) on the function generator. end the Has/DIV (H/D) setting of the storage scope spectrus analyser to produce and assure the warble- tone frequency deviations given.* Center Frequency . uooo as Percent Frequency 11% 13% 16% 110% 150% Deviation Frequency Deviation 80 21.0 uao 800 #000 in He Instrusent Dial Setting Required ED 1100 3250 than 1630 :1 500 vs 3 10 10 10 10 v 2 sh 3 e 7 3 . 8 3 on 3 o 6 H/D 20 so 100 100 500 *Ths sodulation rates used in this study had no effect on any of the seasured frequency deviations and consequently are not shown in the table. Table A33 e 115 The FREQUENCY DEVIATION (FD) setting beat-frequency oscillator, along with the VOLT SCALE (VS and OUTPUT uired on the VOLTAGE (v) on the function generator. and the Hz/DIV (Ii/D) setting of the storage scope spectrus analyser to produce and seasure the warble- tone frequency deviations given.* E‘ Center Frequency - 8000 He Percent Frequency 11% 33% 36% 110% 150% Deviation Frequency Deviation 160 #80 960 1600 8000 in Hz Instruent Dial Setting Required FD thou tuoo 1960 11000 12500 V8 3 10 10 10 10 V 1 .4 11.1 4.1+ 3.8 8.6 H/D 50 100 200 500 1000 4i *‘I‘he sodulation rates used in this study had no effect on any of the aeasured frequency deviations and consequently are not shown in the table. APPUDIX K AVERAGE HEARING THREHOLD LEVEL AND SOUND PRESURE LENEL THRESHOLDS FOR EACH SUBJECT UNDER EACH OF THE UARBLE-TONE COHBINATIONS FOR EACH FREQUENCY 116 "u 1 It? 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E023 Auk—.000- uovdoaouv 030925 $2 0.30.2. APPENDIX L INDIVIDUAL SUBJECT AND MEAN dB DIFFERENCE SCORE FOR EACH HARBLE-TONE COMBINATION AND FREQUENCY 122 0.? ma 3. 3- w... .2.» 9m ; in- :5. fig“; :6- m.N _ o.“ TX? o.N-_ NJAET m.ou_ N.NL‘J- \Nn - 3- “N . as m.“ . o.o . o.“ _ as- 7N- ca _ 0.0 TA- .3th fioN- o; TNFio o.“ r." _ N.Nu 8n): n 3- 3 3 n; ma . m “JP ma- 7;... o; _ 3. 7.? “NT...“ _17 m; _o.N Ta- n." TNF 9N- 8a} m «N. do . N6 3 do 68>. w. o.n fl ...? 7.? o.“ _ 0.« _N.N- n6 _ 9N :6- 06 :4 :6- o6 _ «6 Two w +9? n6 m; o.“ «.o- .oou\N e o.N _ a6- _ “...? n.“ _ 0... H31 o.N _ a... _ 06.. m6 _ «.N Has o; :6 _ ”N- QT m6- 9o 3 o.“ .02.: n.“ mg..- 0.3. m6- m3 0.? o.N «A in- m6 «5 ”.7 o.“ o4 {N m N a n N N m N a n N N m N H 9.83% 9833 0.83% ”.823 0.833 Ron“ Reah Row mm“ RH“ aoavda>on hocosuouh .u: 3.«. you oonouommHo mu omnuo>d 0:» mafia .ovdu noupnanuon and scapua>ov honoavonm mo noupdudnloo soda an ovoonpan Had you cacaoonnv onoauonsn ogv Iona caonnonnp ocovuoapuu: on» no mu ad noououomuan .oad oapufi ~02”ng a: zonukamxoo goeénmmfi. mug m8 mflmoom Hogan—Ho mu 3: g Engm .HQDBSHQZH 123 Q: «.n N; «6. m6 . 2 73 T6 0... E _o.N “5-7.77; 3.-—3- m5- osflwémm 03% R a; o6 o; :6 . .2 H3 W4. “.0 Fa Ta 3-72%? 3 7.?76 3 7.0-72 8&3 9N «N rQN .3. N6- 63% m 9m _ flop? 2 T; T; 3757.“ 3%33 m... 3L 3.7: w Na Na Na o6 :6 . w. m.NH ea _ 3. man 76 TA n.7T.ou_o.a o.o v.7TJ o.o _ NJ-— o.m 08} w... 3. o.o «.0 m.“ w; . o.N _ 3- _ m6 o.o 40.0 7.7 o; _ Ron—o6 o; ngoa o; TEL “5 "EN m6 w.o Eon NJ- 3.0 . ON 3. 0.? m6 .3 mg m.” 9N- 9? fl? 3- 97 m5 v.0- m." 03: m N a m N H n N H m N N m N H 8°36 0.835 8035 N835 0.836 now“ ”an S“ NS 5“ coaudgon .35ng .nx com non 00.3.5956 mu 33d 05 25A .33.." «6333.0- 8.- coavduvov honing Mo 8330.100 no.8 an 3003:» find no.“ 30:00.2» one; on» loan 3055p gov-0.3.3.— 23. «o mu 5 80:23.38 . «3 0.3.8. 12h o.w n.«- o.o o.N- w.«- . o.a _ o.» _ o.m o.N-_ o.N- o.o o.N-_ o.axfl o.N o.N-_\m.N- o.N- o.N-_ m.N-_‘m.N- ooN\Nn a.“ «.o N.o «.o- m.o- m.n _ 0.0 kfi\o.a o." a m.«. we.“ o.o _No.«-_ n.“ n.o _ mnmu¥ n.o o.“ ~[o.«- 0.«- .ooa\ca m.n m.on m.ou m.«n o.N- . m 3 _ 95% O.“ 3.43;? m.N-_n.o-_m.o m.7_o.N-m.T 9L 3.43.. 083 m . o.a .o.o - m.o-. w.oy1 e.Nu . m 0.« _ 3.; 9n 3-7.0-7; oa _n.o- 3. 3-7.? 3. 3-7.??2- 8.} w a.“ 0.“- N.o- m.«- N.NI . 0.0 Q o.“ _ n.N m.o-_ o.N-_‘m.ou m.o4_‘m.au m.ou n.Nu_rm.ou_No.Hn o.NWHNm.N- m.N- ocu\N N.“ N.Nu n.«- m.N- o.nu . n.o n.« m.“ o.NI o.¢I m.~| m.on m.ou o.n| m.mu m.m| m.ou m.al o.wu m.«l oom\« m N H m N a m N H m N H m N a aoonpsm Noonnsm puonpsm Noonpsm poonnnm us“ «on 3... NS Rn nowada>un honozaoum .u: coo“ you oonouoHMNv mu omnuo»: onv mafia .ovuu soupuasuo- as: acuvua>ou honosuonm no nouvunan-oo coco an upoonnau Had you caonuoug» ouoauouga on» scum ”Honoounp oqopuoanuns on» no me a“ uocnououuan .Nad 0H#n9 125 o6 a.” o.N n6 n6 . wéu %m.a _ 3... von— a." A a.N m.“ _o.N _ a.“ o6? 3L m6 o.T_ m6 _ m.N oou\Nm TN- m.N Nam 0.« :J . fun am.” L_H.m.. flon— TN _ m... m.« TN..— _ oi a; _ m6 _ m6 3.« _ {N _ 2.0 03>: L N.Nu «N a; n6 o.N . 33 W 5.- F {N TN- 3-— ...N T... capas _ :6 S. F “.T_ a.N m6 _ a; Ta 0 m. I oéu N6 3.« 5.0 m6 . m 3.- _ «.7 EA: wéu— El 3.« m.ofia.fl 0.0 flou— :Jfimé m6 _ H.7_ :.N 03} m E- 3 2 S. a.” . 9m- _ 9w; 3. .3 _ a; _ ....m 3..— o.o-_ ...m as _ :6 _ .3 .3 _ N.NA a; 25k HKI N.ou m6 Nam m.~ To? «.mn «.wu «.mu 3.0 06 fion a.“ :6 3.« {N in a.“ {N in Jon) m N a m N a m N a n N a n N H Noonpsm #833 0.835 N835 $836 mom“ mom... «2.. «mm RH 53.359 sensuous .um coon Hon oououoEu mu undue: on» 3.3 .38 .331??- ? 334:8 bacon—g no 833918 no.3 3 30035 ads you 30:39.5 28.733 2:. Iona 30:09.2» 0370.32 23 Mo mu 5 3309393 . mi 0.319 126 m.ut n.mn m.NI 0.«» m.nl \ n .00» N QTL n5- 7.? 913%.? 3%: TH- a??? “.0 0.??? 3. m5. H.Nu 9N- H11 o6- L .oou\wu 9? Tan- —o.m- 31— m.o-—o.N.. oéuTN- “.7 317.? “.m. an o6fln6- m5. m6- 9N- ca- as 2: M o D o.N- TE- H3- o.N-_ 3-7.0 °.m-_ “5.4%...- 05-76-76- o.H-_o.H 75 m m 9n- 2.. «51 40.7 H.N- .23 m 3.. 7.??? 06-7...- 3.. o.m-_n.N-_m.N- 3.-—ca Ta- 31?... at... a w 0.5: m.mu n.~| w.~n «.NI .oom\m 0...- TE- 7.2. 3-— 913- EN. 3-7.? 2. 3L 3. 0.?— 3-7.? H.au w.mn w.mn a.ma o.~| .oou\a m.:n 0.0: 0.:«n m.m| o.n| o.ml m.mo m.mu 0.3! o.mu m.~n 0.3! m.mu n.al 0.«1 m N H m N H m N H m N H m N H N836 H836 gonna NSF—Hm gonna $3 3% Na “3 NH... couvua>on secondOHm .um 83 8“ oonouoymuu nu omino>d can mafia .ovdu nowadaauOI can nouvdu>oc honoaaonn no nuuadnaploo undo vd nNOOfinsn and gum uaonuoun» onovnonsn onv noun neonuouna onovnoapnd: 0:» no no ca noonouohudn .a¢< canny 127 nJN- N6. 06 QH QH . HAN- H.NNL “.mHL aflmHL 3.. {H H37— o.H- a; _o.N-_ m... 3.. # o.N-_ n6 8m\Nm oaN- m.N- o.Hu H.N m6 N.NN- TEN- ma? 9N- o.muflo.o Ha-— n.H- m.H in TEL o.N osHTNud ma .oom\mH J N.NN- . o.N-- 4M6 WH.H . . m6 . m maNu _ m.:N.fl.wNu 9.1— o.N.. m6 3.0 _ 0.77.? a; _o.o _m.H o4; o.NLo.H 038 W SN. 31 N.o.. 3.0 n6 . m o.NN- h 98-7%? H.Nwhm.w%.nu ¢.H _ o.N.._ 0.0 «.6 _ o6 _n.o 3.0 _n.o-_ o.H 03? m N.NN- 0:1 N.m.. o.o m.N . _ N.NNPENW— EN. .2-— n.m-fio.n- H.m-_ oz..-— m.H w.o-_ 0.0 A 2 .3 T3 TH 03} m.mNn 5.:l N.NI m.oa «.0 . 98.. o.mN- n.mN- H.N. n6- ma- 0.? 0.? m.N ma- 97 ON H.o.. m.Hu o.N 8.5 m N H m N H m N H m N H m N H Hoonnsm 3036 9833 983% 803% Ron“ Ron mm... mm“ NH... noavua>on honoswmnm ...: 88 93 . oocouohmdu nu onunu>d on» mafia .ovuu nouauasuon and nouvdahov honouunyu no goapandnloo none vd upoofipsu Had nun uaonuonnv oaopaouzn oz» menu uaonuonav onovuoapnd: 0:9 no nu ma noononoumdn .mi flea. APPENDIX M BANKS ASSIGNED TO EACH SUBJEBT FOR EACH UARBLE-TONE COMBINATION FOR WALL'S COEFFICIENT 0F CONCORDANCE 128 BANKS ASSIGND TO EACH SUBJECT FOR EACH UABBLE-TONE COMBINATION FOR WALL'S COMICIENT OF CONCORDANCE Table M16. Hunks assigned to each subject for thirty ramble-tone combinations at 2 50 Hz. “true-Ton. Subjecta' M1355 Sun of Combustion- 1 2 3 links 1. 1xy1 30.0 15.0 12.5 57.5 2. 1%V2 10.0 8.0 12.5 30.5 3. 1£fl0 28.0 7.0 0.5 39.5 0. 1%]8 11.0 19.5 19.5 50.0 5. 1xV16 10.0 10.0 12.5 36.5 6. 1%/32 18.0 25.0 2.5 05.5 7. 32v1 18.0 26.5 7.0 51.5 8. 3%V2 28.0 19.5 7.0 50.5 9. 31%0 21.0 10.0 0.5 35.5 10. 3xy8 20.5 22.0 19.5 66.0 11. 31V16 28.0 22.0 12.5 62.5 12. 3%V32 20.5 15.0 1.0 00.5 13. 6xy1 8.5 20.0 20.0 56.5 10. 6xvz 21.0 26.5 20.0 71.5 15. 6%V0 21.0 22.0 7.0 50.0 16. 6%/8 18.0 15.0 29.0 62.0 17. 6%V16 11.0 15.0 12.5 38.5 18. “/32 16.0 15.0 26.0 57.0 19. 10¢y1 7.0 15.0 2.5 20.5 20. 1011/2 5.0 28.0 19.5 52.5 22. 1oay8 20.5 29.5 12.5 66.5 23. 1oay16 8.5 29.5 27.5 65.5 20. 10%y32 20.5 10.0 19.5 50.0 25. 50¢y1 1.0 1.0 19.5 21.5 26. 50%V2 2.0 3.5 20.0 29.5 27. 502%“ 3.0 2.0 27.5 32.5 28. 50%y8 5.0 3.5 19.5 28.0 29. 50%V16 11.0 6.0 12.5 29.5 30. 50%V32 5.0 5.0 30.0 00.0 w Table A307. 129 links assigned to each subjcct for thirty warble-tone ccnbinctionc 0.1: 500 Hz. Fable-Tom Subjecta' mag Sun of Combinations 1 2 3 Banks 1. 1271 13.0 12.0 13.0 38.0 2. 1572 20.0 12.0 17.0 09.0 3. 1570 16.5 0.0 9.5 30.0 0. 15/8 13.0 0.0 6.0 23.0 5. 15/16 6.5 17.0 21.0 00.5 6. 1fl32 21.5 “no “'00 2905 7. 3171 A 2.5 8.0 2.5 13.0 8. 3372 16.5 17.0 17.0 50.5 9. 350/0 13.0 0.0 9.5 26.5 10. 3178 9.0 12.0 17.0 38.0 11. 3%V16 25.0 0.0 17.0 06.0 12. 32732 5.0 8.0 6.0 19.0 13. 6%71 2.5 1.0 21.0 20.5 10. 6272 6.5 12.0 17.0 35.5 15. 6%!“ 19.0 17.0 2.5 38.5 16. 6%78 21.5 22.0 21.0 60.5 17. 65716 15.0 22.0 6.0 03.0 18. 67732 26.0 8.0 20.0 58.0 19. 1oa71 9.0 27.0 13.0 09.0 20. 1016/2 2.5 25.5 9.5 37.5 21. 10570 23.5 22.0 1.0 06.5 22. 10%/8 11.0 28.0 29.5 68.5 23. 10I716 18.0 22.0 13.0 53.0 20. 105732 29.0 22.0 9.5 60.5 25. 50571 2.5 17.0 20.0 03.5 26. 50772 9.0 17.0 20.0 50.0 27. 50%/4 27.0 25.5 26.0 78.5 28. 50:78 23.5 12.0 27.5 63.0 29. 507716 30.0 30.0 27.5 87.5 30. 50%/32 28.0 29.0 29.5 86.5 r r Tabla A08. cosbinations st 1000 Hz. 130 Ranks assigned to such subject for thirty usrblo-tons Harbin-Tons Subjects' Rnnkings Sun of Conbinstions 1 2 3 Banks 1. 1271 7.5 1.0 10.0 18.5 2. 1772 0.0 5.5 6.0 15.5 3. 1%70 1.5 5.5 10.0 17.0 0. 1%78 0.0 5.5 12.5 22.0 5. 17716 10.0 17.5 25.5 53.0 6. 19732 7.5 5.5 12.5 25.5 7. 3%71 10.0 3.0 1.0 18.0 8. 3772 10.0 21.0 2.5 33.5 9. 3270 10.0 10.0 16.5 00.5 10. 3%78 10.0 9.5 10.0 29.5 11. 32716 19.0 10.0 23.5 56.5 12. 33732 6.0 9.5 6.0 21.5 13. 6271 1.5 21.0 16.5 39.0 10. 6%72 10.0 10.0 16.5 00.5 15. 6%70 10.0 21.0 21.0 56.0 16. 6%78 19.0 21.0 2.5 02.5 1?. 65716 23.5 17.5 21.0 62.0 18. 62732 25.0 20.0 6.0 55.0 19. 10%71 0.0 2.0 6.0 12.0 20. 10272 10.0 9.5 16.5 00.0 21. 10570 21.5 21.0 16.5 59.0 22. 10%78 19.0 10.0 16.5 09.5 23. 10%716 21.5 10.0 25.5 61.0 20. 102732 17.0 9.5 6.0 32.5 25. 50771 23.5 26.0 23.5 73.0 26. 50772 26.0 25.0 21.0 72.0 27. 50270 27.0 27.0 27.0 81.0 28. 50%78 29.0 29.0 28.5 86.5 29. 507716 28.0 29.0 28.5 85.5 30. 50%732 30.0 29.0 30.0 89.0 131 Table Ah9. Ranks assigned to each subject for thirty warble-tone combinations at 2000 Hz. 0 $3533. ‘T—Sfl‘m' zhnkings 3 2'“? 1. 1271 23.5 20.5 28.0 76.0 2. 1272 15.5 29.0 25.0 69.5 3. 1274 18.5 9.0 21.0 93.5 a. 12/8 23.5 20.0 21.0 611.5 5. 12716 7.5 24.5 25.0 57.0 6. 12/32 20.5 12.0 7.5 00.0 7. 3271 23.5 22.5 30.0 78.0 8. 3272 15.5 9.5 17.5 92.5 9. 327% 11.0 16.0 19.0 01.0 10. 3278 18.5 2.0 21.0 03.5 11. 32/16 11.0 12.0 25.0 08.0 12. 32/32 11.0 7.5 21.0 39.5 13. 62/1 7.5 16.0 10.0 37.5 11.. 62/2 23.5 6.0 9.0 38.5 15. 6274 11.0 29.5 21.0 56.5 16. 62/8 30.0 12.0 10.5 52.5 17. 62/16 28.5 16.0 28.0 72.5 18. 62/32 15.5 29.0 28.0 72.5 19. 10271 11.0 9.5 6.0 26.5 20. 102/2 26.0 16.0 17.5 59.5 21. 102/4 15.5 7.5 10.5 33.5 22. 102/8 27.0 20.5 10.0 65.5 23. 102/16 28.5 29.0 10.0 71.5 20. 102/32 20.5 16.0 10.0 50.5 25. 502/1 1.5 1.0 1.0 3.5 26. 502/2 1.5 2.0 2.0 5.5 27. 50270 3.0 ‘b.9 0.0 11.0 28. 5075/8 5.0 20.5 4.0 33.5 29. 502716 0.0 20.0 »h.0 28.0 30. 502/32 6.0 20.0 7.5 33.5 Table A50. cosbinations at MOO Hz. 132 Ranks assigned to each subject for thirty warble-tone 4* E Sun of warble-Tone Subjects ' M139 Combinations 2 3 Banks 1. 1271 22.5 17.0 17.5 57.0 2. 1272 17.5 17.0 22.0 56.5 3. 127k 17.5 27.0 9.0 53.5 b. 1278 27.5 30.0 30.0 87.5 5. 12716 25.0 27.0 28.5 80.5 6. 12732 17.5 20.0 22.0 69.5 7. 3271 7.5 11.5 22.0 41.0 8. 3272 17.5 11.5 17.5 06.5 9. 3270 25.0 27.0 9.0 61.0 10. 3278 25.0 23.0 1.0 09.0 11. 32716 5.5 10.0 13.5 33.0 12. 32732 29.5 17.0 5.0 51.5 13. 6271 7.5 8.0 17.5 33.0 14. 6272 9.5 17.0 26.0 52.5 15. 627k 13.5 11.5 5.0 30.0 16. 6278 13.5 23.0 5.0 01.5 17. 62716 20.5 11.5 13.5 05.5 18. 62732 20.5 29.0 2.0 51.5 19. 10271 11.0 0.5 17.5 33.0 200 10%/2 1305 900 90° 3105 21. 10272 13.5 6.5 22.0 #2.0 22. 10278 29.5 23.0 26.0 78.5 23. 102716 17.5 23.0 13.5 54.0 22. 105732 9.5 17.0 3.0 29.5 25. 50271 1.0 1.0 9.0 11.0 26. 50272 2.0 2.0 13.5 17.5 27. 5027“ 3.5 6.5 9.0 19.0 28. 5056/8 5.5 3.0 26.0 30.5 29. 501716 3.5 “.5 28.5 36.5 30. 502732 22.5 23.0 22.0 67.5 “b1. A51 0 cosbinations at 8000 H2. 133 Ranks assigned to each subject for thirty warble-tone L T “hrhlo-Tvn- ._I_.222122221_!!2§$!sz___§. Sui of Ghnbinations 2 Banks 1. 1271 26.0 20.0 18.0 60.0 2. 1272 22.5 28.5 30.0 81.0 3. 1270 19.5 25.5 19.5 60.5 0. 1278 19.5 15.5 26.5 61.5 5. 12716 29.0 15.5 16.5 61.0 6. 12732 16.5 15.5 29.0 61.0 7. 3271 26.0 23.0 10.5 59.5 8. 3272 16.5 28.5 16.5 61.5 9. 3270 16.5 28.5 21.0 66.0 10. 3278 22.5 28.5 26.5 77.5 11. 32716 26.0 23.0 28.0 77.0 12. 32732 30.0 15.5 23.5 69.0 13. 6271 28.0 7.0 15.0 50.0 10. 6272 22.5 10.0 7.0 39.5 15. 617“ 13.5 15.5 23.5 52.5 16. 6278 10.5 23.0 19.5 53.0 17. 62716 22.5 20.0 12.0 50.5 18. 62732 10.5 25.5 23.5 59.5 19. 10271 8.5 8.5 9.0 26.0 20. 10272 7.0 12.0 10.5 29.5 21. 10270 8.5 8.5 10.0 31.0 22. 10278 16.5 15.5 8.0 00.0 23. 102716 13.5 11.0 13.0 37.5 24. 102732 12.0 20.0 23.5 55.5 25. 50271 3.5 1.0 2.5 7.0 26. 5W2 600 2.5 500 1305 27. 50272 3.5 2.5 5.0 11.0 28. 50278 1.0 0.0 2.5 7.5 29. 502716 3.5 6.0 5.0 10.5 30. 502732 3.5 5.0 1.0 9.5 E=======F:‘ +_L_, :j::;. «4====: FIHIIIIH 002 7 6 ”7 293 031 I!“ Will