ml Wm M m ~ ' . NORMAL gamma meRE-N’S 7 z'N'rmusmm'rY ON TIME Commassm )1 ' ‘ I = chDITIGNsos THE mp: ,‘ - rhesus:- w mWfifihméi Ari! : “MICHWK'STAT: mm ffiTYZV ’ u l. a g?5 . o . I . . : ‘ . ' ‘ . ' V - i " ': Accepted by the faculty of the Department of Audiology and Speech Sciences, College of Communication Arts, Hichigan State University, in partial fulfillment of the requireaente for . Beasley, Ph.D. 31 $1150 w NOFC in Speech h Sm Stu by the Tin diaglos SUbject listene for ‘Spe Little as wel] SPEECh T1 hearin. CiiScri CdtiOn linden IEVels L\ V ABSTRACT NORMAL HEARING CHILDREN'S INTELLIGIBILITY ON TIME COMPRESSED CONDITIONS OF THE WIPI By Paula Jane Shoup In the area of speech perception, the use of time compressed -. Speech has been the focus of several investigations . The purpose of such studies has been to investigate the effect of terrporal alteration, by time compression, upon the auditory perception of speech signals. Time compressed speech stimuli have recently become an effective, diagnostic tool in determining auditory perceptual abilities of various subject populations . Most of this research has provided data for adult listeners . However , a large percentage of the total population seen for 'speech and language and .hearing evaluations is. comprised of children .’ Little information is available to indicate how normal hearing children ,‘ as well as other subject populations of children, perform on standard speech discrimination tasks under .time compressed conditions . This study investigated the effect of time compression on normal hearing children' 3 performance using an appropriate standard speech -. discrimination measure, the Word Intelligibiliw by Picture Identifi- cation (WIPI) test. A total of ninety subjects divided into, three age , groups (14, 6, and 8 years) were each presented four lists of the WIPI under time compressed conditions of 0%, 30% and 6096 at two sensation levels, 32 dB and 16 dB. Each subject received a 096 time compressed ‘ conditior sated a1 item phi time as? with an e The groups u were CDT? The 13081 Gex age inc: titre co 32 (13 t found, four 11' Hem dj Wilda? Paula Jane Shoup ' condition prior to either a 30% or 60% condition. Two lists were pre- sented at 32 dB SL prior to presentations at 16 dB SL. Four practice itexrs preceded each list in order to familiarize each subject to the time compressed stimuli. Stimuli were presented under rearphones , with an equal number of right and left ears tested. 'Ihe mean percentage correct scores for each of the three age groups under each condition of time compression and sensation level were computed. Right ear scores and left ear'scores were canpared. ‘Ihe most frequently missed words for each age group were determined. ' General results of the study indicated that scores improved as age increased. In addition, scores decreased as the percentage of time compression increased and as sensation level was decreased from I 32 dB'to 16 dB. Minimal right versus left ear Score differences were found, but no consistent trends were noted. Scores for each of the four lists of the WIPI were compared. Results of the present study were discussed with reference to previous investigations using subject populations of children and time compressed Speech stimuli. NORMAL HEARING cumREN's MELIGIBILITY on TIME COMPRESSED . CONDITIONS or THE wrpr * By Paula Jane Shoup ‘ A'IHESIS Submitted to Michigan State Universtiy in partial fulfillment of the requirement for the degree of MASTER OF ARTS Department of Audiology and Speech Sciences 1975 to ex;mx35 Haki.vfljo assistan mm t I w Lansing and eSpe for his Fix 531d 10v; Offerng Acmmmnsrm I would like to thank the members of my committee for their guidance throughout the duration of my research. A special thanks to Dr. Fred Bess for serving as a committee member. I wish to express my gratitude to Dr. Daniel. S. Beasley not only for providing the impetus for this thesis and his direction of the thesis, but also for his guidance throughout the course of my completed graduate studies . To my many- friends who assisted me in many different ways, III wish to express my thanks. ..I would especially like to recognize Dr. Jean ' . Maki who hterrupted her own hectic schedule to lend countless hours of assistance and inspiration throughout several long months. Also, I thanks to Toni Tryon who unrelentlessly searched for subjects. . I would like to thank the many parents and children from the. Lansing area for their interest and participationin. this study _....., and especially a mischievous four year old who shall long be remembered for his "performance." I g p ‘ D _ Finally, a very special thanks to Ron, who remained as patient and loving as possible throughout the entire difficult year, and who offered his assistance and support in every way. LIST OF (HAPIER III. TABLE OF CDNTENTS mm or TABLE 0 O O 0 CHAPTER I. INTROIIJCI‘ION . . . Historical Aspects of Time Compression . Intelligibility of Time Compressed Speech:- Intelligibility of Time Compressed Speech: Children . . Statement of the Problem II . MRDIENTAL PROCEwRES . subjects . . . Preparation of Bq>erimental Tapes Testing Procedures . III. RESULTS . . . . Time Compression and Sensation Level ' Effect of Age . . Ear Differences . List Differences and Analysis of Errors IV. DISCUSSION' . '. . Time Compression and Sensation Level Effect of Age . . Bar Differences . List Differences and Analysis of ErrOrs Clinical Implications iii '11 13 ' 16 15 ' 17 '20 2a ' 2a '28 28 30 ~ 33 39 35 33 39 no V. SUMMAW . A. PRACTICE ITEMS BY LIST B. CALIBRATION PROCEDURES AND INSTRUMENTATION C. INFORMATION SHEET D. WIPI SCORE SHEET E. INDIVIDUAL DATA LIST OF REFERENCES . .iv Page #3 an as In '48 us 55 Table 1. LIST OF TABLES Mean intelligibility scores in percent on the WIPI for each age level, sensation level, time compres- sion percentage and right and left ear presentations Mean difference scores on the WIPI between 16 dB SL and 32 dB SL for each age group and each time com- pression condition of the present study (P). The Beasley et a1. (B) and the Sanderson and Rintel- ‘mann (8) results are also shown for comparison pmses O O O O O O O O 0 Mean percent scores on the WIPI for each condition, of time compression and sensation level for age groups 14, 6, and 8, for the present study (P). The Beasley et a1. (B) and the Sanderson and ’ Rintehnann (S) results are also shown for comparison pmses O . O O I O O ' O O 0 Mean difference scores. on the WIPI in percent between ages l} and 6 and between 6 and 8 for each time com- pressed condition. Beasley et al. '3 (1975) values are indicated in ( ) . . . . . ._ Mean percent correct scores for each list of the WIPI for all age groups combined at each time com- pression condition for the present study (P) and for the Beasley et a1. study (B) for 6 and 8 year olds at 16 dB SL . . . . . . . _ . The ten most frequently missed mrds on the WIPI at all levels of time compression and both sensation levels for each age group . _ . . . . Mean SRI‘ scores in dB according to age groups for - the present study, Beasley et al. (1975) and Sanderson and Rintelmann (1971) . . . . . Page 25 25 27 29 31 32 37 CHAPTER I INTRODUCTION The area of time compressed, or accelerated, speech has bean the topic of several investigations in the area of speech perception. The primary objective of these studies has been to investigate the effect of temporal alterations via time compression upon the auditory perception of speech signals . A Most of the research dealing with the perception of time com- pressed speech has provided data for adult listeners . The effect of time compression on the performance of normal hearing adults as well as hearing impaired adult populations and ’ brain damaged adult popula- tions has been determined. Time compressed speech stimuli have become an effective diagnostic tool to determine the auditory per- cepimal abilities of these populations . In addition to adults , however, a large percentage of the total population seen for speech and language and hearing evaluations is comprised of children . A paucity of information is available to indicate how normal children perform as compared to adult pepulations when listening to temporally distorted, or time compressed, speech. No research investigating the effect of time compression upon the _ auditory perception of hearing impaired , learning disabled , or brain damaged children has been completed. Therefore, no information exists to relate the performance of these populations to a normal population . This thesis concerns the effect of time ccnpression on normal chil- dren's performance using a standard Speech discrimination measure. Historical Aspects of Time Compression . Previous investigations have demonstrated that temporal factors affect the listener's auditory perception of speech stimuli (Aaronson , 1967; Beasley and Shriner, 1973). Two of these factors which have been shown to be important in auditory perception are [the rate at . which stimuli are presented and the. duration of the stimuli (Aaronson, 1967). In a time compressed condition, both the rate of presentation I and stimulus duration are altered from the original signal in that the rate of signal presentation increases and stimuli duration decreases . Early attempts to study the effects of time compression resulted in undesirable acoustic characteristics of the speech signal associ- - ated .with the method of time compression used. For example, one method used was that of speaking at a more rapid rate . Although a . simple procedure involving no special equipment , this method resulted in undesirable changes in articulation and inflection. Furthermore, ' the range of compression was limited, since the average speaker can- not produce. intelligible speech at a rate greater than approximately 30% of normal (Calearo and Lazzaroni, 1957; ldeQuiros, 1951+). Addi- tionally , it is difficult for the speaker to speak at a rate which does not. fluctuate, especially for long units of V stimuli. An additional method of increasing the rate of speech signal pre- sentation was to tape" record the original signal and replay it at a speed faster than the original recording (Fletcher, 1929; Foulke, 1966; Garvey, 1953; Klumpp and Webster, 1961). Again, this was a2 simple, inexpensive procedure , but it resulted in an undesirable upward shift in frequency . Sampling methods in which a segment of the original sigral is reroved have been shown to have the advantage of minimizing the shift in vocal frequency. Miller and Licklider (1950) used a rapid switching arrangement thatpermitted the speech signal, in this case monosyllabic words , to be turned off and , on periodically , thus elimi- nating a certain percentage of the original signal. They did not re- - move the silent or "off" periods from their signal, so total pree . sentation time was unchanged, although the actual duration or "On" portion of the stimulus word decreased. ‘ ‘ i I Garvey (1953) used a manual sampling method in which samples of the original signal were. removed. He accomplished this by manually splicing out small segments of a taped signal and joining the renain- ' ing segments together . Although this method permits a specific portion of the signal to be removed or retained, it was found to be excessively tedious and time-consuming . I . An electromechanical means of sampling speech was developed by Fairbanks, Everitt, and Jaeger (1959). This speech compressor made use of a tape loop onto which a signal was recorded. This loop then ' passed over a rotating head assembly comprised of four record heads, at which point portions of the signal were retained and recorded onto a variable speed tape recorder. This method permitted high quality compression up to 80% time compression with minimal pitch distortion. . I; Compressors which accomplish a similar effect as the depressor developed by Fairbanks et al . include the Lexicon Varispeech I - (Lac, 1972). This portable apparatus uses cassette tapes and is con- siderably less expensive and easier to operate than the Fairbanks' compressor. Essentially, the Varispeech I is comprised of a Wollensak tape recorder. and an analogue mini-computer. The signal is recorded ‘- on the Wollensak and compression or expansion is achieved via the mini-computer. Standard-size. pomputers and speech synthesizers have also been utilized to study the effects of time compression. In addition to the advantages of other electromechanical compressors, this refined allow for selective discarding when processing the signal. These methods A are , however , very expensive and as yet in the developmental stage r I Intelligibility of Time Compressed Speech: Adults -‘I‘wo factors of speech and language which have been investigated V ' under time compression are the intelligibility (Garvey, 1953; Fair- 2 banks and Kodman, 1957; Luterman et al., 1955; Daniloff, at sin-1959; ’ Sticht and Gray, 1969; Beasley et al., 1972a, 1972b; and Korflc’le at al., 1971+) and the comprehension (tam-m et al., 1957a, 1957B, 195%; Foulke et a1. , 1962) of the time compressed speech signal. Intelligibility is measured by testing the listener's“ ability to ' repeat a' brief message, usually words or sentences , - accurately. This may be tested by an oral or written response and is usually expressed as a percentage of correctly identified itens . I Comprehension is S examined by presenting a selection auditorily at a time compressed rate to the listener and subsequently testing him on the information contained within the selection. Objective tests are generally used to obtain the comprehension score . Garvey (1953) using the manual sampling, or "mop-splice," medod to achieve temporally accelerated speech , investigated the effect of acceleration upon the intelligibility of spondee words . Results indicated that intelligibility scores remained high. even at a rapid rate of acceleration. Scores remained above 95% for rates up to two times (50% compreSSed) the original signal rate. Mean intelligibility scores did not drOp below 80% until 67% time compression was achieved, and did not fall below 50% until a 75% time compression rate was 7 attained. . Garvey compared these results to those obtained by accelera- ting the signal by the fast-play method with its associated upmrd shift in frequency. At two times theoriginal rate, or 50% time com- pressed, using the fast-splay procedures, 65% intelligibility scores. ' resulted (compared to 95% for manually oorpreSSed speech). Scores dropped below 10% for 2.5 times the speed of the original message (compared to 93% for manually compressed speech). Fairbanks and Kodnan (1957) also inVestigat'ed the effect of time cmpression upon speech intelligibility at rates varying from l+035 to 90% time compression. Phonetically balanced (PB) words were processed ' using the Fairbanks' compressor to achieve the desired experimental conditions . The intervals of discard , that is the duration of the segments removed from the speech signal, were also varied in duration. In addition , listeners received training to familiarize them with the vocabulary used during the investigation . For the shorter discard intervals , intelligibility remained at 90% or better for rates of time compression up to nearly 80%. The authors concluded that if intelligibility is to vary primarily as a function of I the conpressed signal duration, then a discard interval which is short in relation to the signal unit is required. . The effect of time compression with and without frequency dis- tortion was investigated by Daniloff , Shriner, and Zemlin (1968). Stimuli were eleven different vowels produced in the /h-V—d/ context. Experimental conditions were derived using the compressor developed by Fairbanks et al. (1951;). Both a male and female speaker were used to determine if speakerhsex differences would occur under the experi- mental conditions of the study. Time compression values used were i 30% to 80%, with each successive condition increasing in 10% steps. Results indicated that time compressed vowels were more intelligible at all conditions than were frequency distorted vowels . In contrast to the Fairbanks and Kodman (1957) study, a rapid decline in intelli- gibility was noted at 70% time compression instead of the previously reported 80%. However, Fairbanks and Kodman used a discard interval of 10 msec and trained listeners, whereas Daniloff et a1. uSed a discard interval of 20 msec and unsophisticated listeners . In terms of speaker-sex differences , the female ‘speaker was generally more intelligible than the male for all conditions of frequency and time distortion. Similar vowel confusions were noted for both speakers. Results showed that duration was a critical factor in the intelligibility of vowels (i..e. , a "long" vowel when time caupressed was often mis-identified as a "medium" length or "short" vowel.) In addition , the rapid linear decline of vowel intelligibility in con- ditions of greater than 3096 frequency distortion indicated that fre- quency is not redundant in the sense that duration is for vowels. Beasley, Sclminmer, and Rintelmann (1972b) studied the effect of time compression upon the intelligibility of CNC monosyllables. The authors presented to normal adult listeners four lists of Form B of the Northwestern University Auditory Test #6 (NU-6) (Tillman and Carhart, l966) at 095, 30%, MR, 5096, 60% and 7096 tine compression- rates. In addition, four sensation levels (8, 16, 24, 32 dB) were used, and the effect of ear differences was also investigated. Results indicated a gradual decrease in intelligibility scores mrtil the 70% time compression condition, at which point a marked decrease in intel-p ligibility occurred. As sensation level increased, intelligibility also increased. Ear differences were fomd to be minimal. A similar study was "conducted by Beasley, Forman, and Rintelmann (1972a). Using the same test stimuli. (NU-6) and normal listeners as subjects, the effect of a higher sensation level, #0 dB, was in- vestigated under time compressed conditions . Results indicated a slight, non-significant improvement in scores. I In addition to the young adult, normal hearing populations used as subjects in the preceding studies , several invefiigators have studied the effects of time compression upon aging and/ or pathological populations. Time compressed speech stimuli have been employed.in diagnostic audiology in.accordance with the 'subtelty principle' presented by Jarger (1960). Jerger hypothesized that as auditory pathways increase in complexity, the stimuli needed to adequately study these pathways :must also increase in complexity. Related to this concept are the findings that persons with a damaged auditory cortex may still perfionn well on standard nonsdistorted speedh discrimination measures and.pure tone tasks. These results are due to the intrinsic redundancy of the hearing mechanism as well as the extrinsic redundancy of the signal (Calearoand Lazzaroni, 1957). ' Tb reduce the extrinsic redundancy of the signal, speeCh.has » been distorted by various methods, including time compression. The use of time compression is based upon the assumption that time plays a significant role in auditory perception. Results indicatinga.use ftm*accelerated.speedhin the diagnosis of lesions in the central auditory pathway were presented‘byCalearo and Laszaroni (1957). In_ addition, an investigation.by'deQuiros (196h) determined.that‘time ‘ compressed speech could be usefu1 in.the differential diagnosis of .auditory disorders. _ I ‘ Lutenman, welsh, and Melrose (1966) investigated the effects of age and sensori-neural.hearing loss upon the intelligibility of time compressed speedh using normal hearing adults, young adult sensori-v neural impaired, and.aging sensorieneural impaired subjects. The CID WL22 test of auditory discrimination was presented at ratios of 10% and.20% compression.and 10% and 20% time expansion. Both the time compressed and the time expanded conditions yielded a slight decreaSe in.intelligibility scores. The normal hearing group scored higher than the young sensori-neural group, WhiCh, in turn, scored.higher . than the aging sensori-neural group. The authors suggested, however, that the manner of performance of the aged population was not signi- ficantly different'frontthat of the other'two’groups for the two levels of compression and expansion. I ‘ Sticht and Gray (195 9) investigated the intelligibility of time compressed words for young (under 60 years) and old (over 60 years) sensori-neural and normal hearing populations . Time. compression rates presented were 0%, 36%, 1’.6% and 59%; Stimuli were the wbrds from the CID W—22 lists. Results showed that age, for both The normal and I sensori-neural impaired hearing groups , increased the ntnber of dis- crimination errors . It was determined that the main effects of hearing ability, age and amount of compression were highly significant. The authors concluded that aged populations have special difficulty in discriminating accelerated speeCh , and additionally. that sensori- neural hearing impairment was not a necessary requisite to a decrement in the intelligibility of temporally altered speech for the aged. 4A ‘similar'result. was fOund by Kbnkle, Beasley and Bess (197H). Kbnkle- et al. studied the effect of time compressed.speech upon the intellié gibility of different age groups of elderly subjects. Subjects ranged in age from.5u to 7% years and exhibited normal pure—tone hearing thresholds. ‘Word lists of the NU¥6 auditory test were pre- sented.under conditions of 0%, 20%, ”0% and 60% time compression. Three sensation levels (2”, 32 and HOdB) were investigated. Results indicated poorer scores as age increased and also as time compression 10 increased. In addition, scores improved as sensation level increased. The authors concluded that , in accordance with the Sticht and Gray results , percepmal difficulty with accelerated speech increases as ' a function of age. Although the Beasley et al. (1972a, 1972b) data showed minimal differences berw‘een right and left ear scores for normal hearing. adult listeners, different results may be expected for certain patho- logical groups. Kurdzi‘el and Norfsing'er (1972) investigated the in- te‘lligibilify of films impressed speech using adults with cortical brain damage as Subj eats. Although their data indicated no significant ' differenCes between contrelaterai and ips ilaterel ears (re. ' the cortical brain damage) using conventional pure tone, special pure tone, and non-dietorted speech audionefi‘y tests , they did observe that at 60% time owpmssion, scores for the ear Contrelateral to the damage showed pOorer scores, than the ipsilateral ear These results indi- cated the usenflness of time donpression as a detection method for lesions of the auditory oor’c‘ex. ' ‘ 9 These selected studies indicated that not. only did the method and rate of time compression affect the resulting intelligibility Scores , but that additional factors must also be considered. The subject population, the. sophiStiCation of the listeners , the sensation level at which the stimuli are presented, the discard interval, and Speaker-sex differences may also influence the resulting intelligibility scores of time compressed speech. ll Intelligibility’ of Time Compressed 'SReeCh: Children , Most of the studies related to the use of time carpressed speech in audiological evaluation have used normal hearing young adults as their populations . Investigations using children as subjects have been few in number, yet children comprise a significant percentage of the population seen for audiological and speech and language evaluations . To investigate the effect of time compression upon children ' s auditory perception of speech , appropriate stilmlli must be used. One measure of speech discrimination frequently used in audio- logical testing with children is the Word lntelligibility by Picture Identification (WIPI) test (Ross and Lerman, 1970). The test was. developed to asSess the speech discrimination ability of hearing- impaired children . In developing a test particularly appropriate for ’ children, the authors alleviated problems associated with conventional speech discrimination tests by using words which were familiar to children. Further, a picture-pointing responSe was required of the ’child , thus avoiding the problem of articulation errors which could yield a misinterpreted or unintelligible oral response. The entire test consisted of four lists of twenty-five. plates of six pictures each with only four of. the pictures on each plate used as test stinmli. The other two pictures served as foils. Each test list consisted of different test stimuli arranged so that no stimulus item was used on more than one list. . Sanderson and Rintelmann (19 71) presented normative auditory ulirly Gated 1 year cl lities . - in SCI): 12 discrumirla‘ticn data for normal hearing children using discrimination measures developed for use with children. One of the measures used was theWIPI. Subjects were sixty children grouped by age from 3 1/2 to ll 1/2 years of age with an interval of two years between each group. Sanderson and Rintelmam concluded that the WIPI was partic- ularly appropriate for the 3 U2 year old group. p The authors indi- catedfllattasksrequiringanorelresponse couldbeusedwithS 1/2 year old subjects who demonstrated adequate speech and language abi- Beasley ct al. (1975) studied the effect of time compression upon normal hearing children's perception of verbal stimuli using the WIPI and an additional speech discrimination measure. Three conditions of time compressim, 0%, 309a and 6096, presented in sound field atitwo sensation levels, 16 dB and 32 dB, were investigated using sixty subjects divided into three age groups 0+, 6 and 8 years). Results indicated that time compressed speech discrimination ability increased as age increased and as sensation level increased. Discrimination ability was found to decrease as the percentage of time compression increased for both sensation levels. At 30% time compression scores ' were slightly lowerthan those at 0%; however, a marked decrease in scores , especially for the more difficult 16 dB SL condition, occurred at 60% time compression. Scores at) 32 dB SL, as compared to 16 dB SL, were generally improved, with the greatest improvement found at the 60% time compression condition. An exception to this effect was noted for the 8 year old subjects where the higher sensation level resulted in increased scores by approximately the same amount for all 13 rates of time compression. As time compression increased, age groups were divided by increasingly larger amounts . However, more differences occurred between the '+ and 6 year old groups than between the 6 and 8 year olds. Overall, the greatest score differences occured between the 6 and 8 year olds at 16 dB SL at 60% time compression. Additional research is warranted to further investigate normal childrerl's perception of time compressed speech stimmdi. Additional factors, such as right/ left ear differences, should be included to determine if ear advantages exist in normal hearing children . Popu- lations of hearing-impaired, learning disabled , and brain damaged I children should be included as subject groups in studies of time I compression to determine differences in their performance as compared to normal populations Statement of the Problem Several investigations have determined the effects of temporally distorted stimuli upon normal hearing adults , hearing-impaired adults , and adult populations with cortical brain (damage (Beasley et a1 . , ll972a, 1972b; Fairbanks et al., 1957a, 1957b, 1957c; Garvey, 1953, Kltmpp and Webster, 1961, Konkle et al., 1971+; Kurdziel and Noffsinger, 1972; Luterman et al., 1966 and Sticht and Gray, 1969). A minimal amount of research regarding the effects of time ,com- pression with normal hearing children exists in the literature (Beasley. et al. , 1975). General results of the Beasley et al. study show that discrimination scores decrease as a function of time com- pression but increase as 'a function of age and sensation level. 1'4 In comparing their scores under the 096 time compressed condition with those of Sanderson and Rintelmann (1971), Beasley et al. fermd their results to be lower. One explanation suggested by Beasley er al. for the lower scores was the different procedures for detem Sfi' values. Sanderson and Rintelmann's procedure resulted in a greater number of words being presented, possibly leading to fatigue em a ' higher SK? score. The SRT procedures used in the presefit study were the same as those of Beasley et al. to allowifo‘r the presentation of fewer spondee words , thus lessening the chance for fatigue and result: ing in an inaccurate SRT Value. ‘ . i The random presentation order of both sensation level and time compressed conditions used in the Beasley et al. study probably fe: ' sulted in undue variability of results. Procedures of the present study were more like those normally used in a clinical setting. The WIPI, a closed set discrimination measure, was presented sinee fhie discrimination task has been shdwn to be particularly appropriate. ' for the ages of the‘subject population of the present study éépééiéll’y‘ under time compressed conditions (Beasley et al. , 1975).- NO susjéot ' received more than four lists of the WIPI, thus eliminating any re= petition of lists . Additionally, eaCh subject received a zero percent time compressed condition prior to either a 3096 or” 60% céfidi- . tion. Subjects received two lists at 32 dB SL prior to presentations at 16 dB SL. Four practice items preceding each list were included f5 ' familiarize each subject to the time compression sti1m11i. I. Subjects were presented stirmfli under earphones rather than in 15 sound field as in the Beasley et al. study. Equal ntmtbe’rs of right and left ears were tested. Although the Beasley et al. (1972a, 1972b) data indicated minimal differences between right and left ear scores for normal hearing adult listeners , different results may be expected for certain pathological groups , as indicated by the Kurdziel and Noffsinger (1972) study. Data‘for children responding to time com- pressed speech under earphones have not been established; therefore, normative data do not exist as a comparative measure . Nor have data been reported to show differences , if they exist, between scores obtained from the right and left ear. . I A In summary, the purpose of this study was to determine the effect I of time empression upon normal hearing children's intelligibility of» a closed set speech discrimination measure. - Stimuli were presented, under earphones at two sensation levels . Specifically , the f01lowing questions were investigated: 1 1.. What effects would time compressed conditions of 0%, 30% and 6096 have upon normal hearing children' s speech intelli- gibility scores using a standard speech discrimination (measure (WIPI)? ‘ 2. Would these effects differ for age level (1+, 6 and 8 year olds), sensation level (16 and 32 dB), and/or right and left ' I ear? ‘3. how would the results of the present study compare to pre- vious findings with normal hearing populations using time compressed conditions? CHAPI'ERII MAL PROCEIIJRES Ninety normal hearing children in three age groups were presented the word Intelligibility by Picture Identification (WIPI) speech dis- crimination measure under earphones at three conditions of time com- pression (0%, 30%, and 60%) and two sensation levels (16 dB and 32 dB). Subj ects Ninety normal hearing children with normal intelligence were the subjects of this study. Thirty children each comprised the following groups: Group I, age 3 years-6 months to '4 years-6 months (M = 1} years-j . 0 months); Group II, age 5 years-B months to 6 years-6 months (M = 6 years- 0 months); Group III, age 7 years-6 months to 8 years-6 months, (H = 8 years-0 months). 0 , In order to qualify as a subject for the.experiment, each child was given individually a bilateral pure tone air conduction screening test at 20 dB (re: ISO 1961+) for the followingfrequencies: 125:, 250, 500, A 1000, 2000, 14000, and. 8000 Hz. Any child who did not pass all frequencies for each ear was not included in the study. The experimenter conversed with each child prior to the determi- nation of the Speech Reception Threshold (SRT) so that any deviant artic- ulations could be noted and did-not affect those responses accepeted as correct. In addition, the University of Akron Articulation Identification 16 nu —-._l'."-..’ ‘. ' t 17 Test was also administered to each subject to deterfiiiéhe aeieaation GITOI‘S. Preparation of Experimental Tapes The four lists of the Word Intelligibility by hietae identifia- cation (WIPI) test of speech discrimination were recorded by a male, General American , experienced speaker. The speaker satisfies normal 4—...1.‘ fundamental frequency (f0 = 105) and speaking rate (13$ wan reading avg rate). u The tapes were recorded on an Ampex AG HMO-B tape recorder (fie: k quency response * 2 dB EEO-15,000 Hz). The speaker wasseated’ in a ' single-walled recording booth with a two-way window. f An. Electra Voice (Type 635A) microphone was used throughout the recoraaofng proa- A W meter was positioned inside the recording ber so that the 2 speaker was able to note the level at which he was speakihg; 'I'hie Vii I meter was adjusted to correspond to the reading of the Vii meter of the Ampex AG lino-B tape recorder. Two experiended observers firinitored the level of ‘ each speech production as indicated on the Vii meter. 6f the (Ampex recorder. . 1 Each item of the WIPI was produced three times by the speaker. The carrier phrase "Show me. . ." preceded each test item.- The speaker was instructed to peak his productions of the carrier phrase between 0 and -2 dB, and then produce the stimulus word using fiefimal prosodie cues. If either of the two observers or the speaker was fiat~ satisfied with at least one of the three productions , the speaker-7 reproduced the item until a satisfactory production was achieved; Four practice 18 items and identifying information for each list of the NIH, as well as for each test condition, was also recorded. (Practice itmes for each list are indicated in Appendix A.) Prior to the recording of the test stimuli, a sweep tone (50— 15,000 Hz) and a 60 sec 1000 Hz calibration tone were recorded onto the master experimental tape . A Bruel and Kj aer Sine-Random Generator (TyPe 1021+) was utilized for this procedure. The recording of the. calibration tone and the test stimuli was monitored by TDH '39 head- phones with MX til/AR cushions connected to the Ampex AG 600-2 recorder. To record the test stimuli , the tape was auditorially and visually monitored by two observers using earphones and a Bruel and Kjaer Elec- trcmic (Voltmeter (Type 21409) to select the most appropriate test stim- uli. from each group of the recorded items . These items were copied . from an Ampex AG I«MO-B tape recorder, via the Bruel and .Kj aer Electronic Voltreter, to an Ampex AG 600-2 tape recorder (frequency response a 2 dB 50—15,000 Hz) in order to create the experimental master tape. , The master tape was 'then recorded from the Ampex AG 600-2 re:— corder to (a cassette tape using a Sony Solid State/Cassette-Corder' (TyPe TC 180 AV). The three test conditions of 0%, 30%,and 60% time-- compression were made from the cassette tape using the Lexicon Vari- speech I time conpressor (Lee, 1972). A Beckman 61|+8 Eput and Timer (frequency counter) was connected to the Lexicon Varispeech I to determine the fréquency of the pure tone recording on the cassette tape . Frequency values for each per- centage of compression were determined according to the following 19 formula: 100 - % time compression = 1000 1000 x Therefore, when using a 1000 Hz pure tone for calibration, the appropriate frequency reading was 1000 Hz at 0% time compression , 11:23 Hz at 30% time compression, and 2500 Hz at 60% time compression. The appropriate frequency coimt for each of the rates of time compres- sion was maintained for at least eight of ten readings displayed on the Beckman instrument . g . I The pitch-restoring computer of the Lexicon Varispeech I time compressor was not activated during this calibration procedure so that p a higher frequency output resulted as the percentage of compression ‘ increasedfram 0%. _ (I i A Following the calibration procedures , the time compressed stlmnili. were recorded onto magnetic tape using the Ampex AG 600-2 tape recorder- from the Lexicon Varispeech I . In order for the frequency (pitch) to i be restored to normal during the time compression procedures, the computer of the lexicon Varispeech I was activated. 0 Following the completion of the above recording procedures , the 2 intervals between stimulus items of the time. compressed conditions were spliced from the tape . Between each item the magnetic tape was removed and replaced with leader tape . Each section of leader tape spliced onto the tape was approximately 30 inches long , equivalent to. four seconds in duration when played at a speed of 7 l/ 2 inches per Second. Color coded leader tape was spliced between the three 20 time compression conditions and between each of the WIPI lists in order to permit the experimenter easy identification and location of each list and each condition. Testing Procedures Each subject was tested in a two—room double walled, sound treated audiometric suite (IAC series 1200). The rooms of the testing Suite were divided by a window which allowed the subject and the examiner to be in view of each other. . A Beltone Model 15C Clinical Audiometer was used for pure tone screening . For each test presentation, the taped signal was directed from an Ampex AG 600-2 tape recorder through a Grason—Stadler Model 0 162. Speech Audioneter to the accompanying TD-I 39 earphones with MX Lll/AR cushions. The 1000 Hz calibration tone of the recording was ' adjusted so that the VU meter of the speech audiometer indicated a reading of 0 dB. Preceding each testing day, the Beltone and Grason- Stadler audiometers were calibrated to meet established standards (ANSI, 1969). (Calibration procedures and instrumentation are in-4 eluded in Appendix B). ' . Following the hearing screening test, the Speech Reception Thresh- old (SRI'). for either right or left ear of each subject was determined using earphones . The same earphone was used for both right and left cars. A recorded list of the Utley Children's Spondees (Utley, 1951) was, used for this procedure . The taped spondees were diregi from \\‘ an Ampex AG 600-2 tape fiddfierthrough the Grason-Stadler Model 162 , \\~./ 21 Speech Audiometer to the accompanying earphone . Prior to the estab— lishment of the SRT, each subject was instructed to repeat each spondee word as the examiner read the list. A short screening test of articulation was also given , and the examiner determined if articu- latory production would affect test responses. Directions read to each subject before obtaining the SRI' were as f follow: I'm going to say some words and I'd like to have you say the words after me. . . Now you'll hear the words coming from here (experimenter points to the earphone). Some of the words will be very soft so listen carefully and say the word you think the man said. I will be . sitting in the next room, but I can still hear you. Following these directions , any questions the subject had were answered. ' The SRT for each subject was determfined according to the following i procedures as described by Beasley et a1. (1975): The intensity level for presentation of the spondees ; was set at 20 dB to 30 dB HL initially and was decreased in 1} dB steps following word presentations at each level. Initially , two words were presented at each level until the point where the subject began to respond incorrectly. From that point a maximum of four words was presented at a each level. In this manner , determination was made of the lowest intensity level at which the subject could repeat 50% of the words presented, that is, at least two out of _four words presented. - Subject responses for the SRT were monitored through an earphone con- nected to the speech audiometer. , Following these procedures , the experimental conditions were pre- ' sented. The subjects were randomly assigned to either a right ear or 22 left ear condition. Each subject received the following insiructions. Here are sole pages that have pictures on them. In a fa: minutes you. will hear a man telling you what pictures to show me on the page. Some of the time he may sound funny or different but look at the pictures on the page then point to the picture he tells you to show me . 1", For each list under each time compressed condition , four practic items preceded the actual test stimuli so that the subject was familiarized with listening to each percentage of time compression presented. During the presentation of the experimental tape, the examiner remained in tl'e‘room with the subject. An assistant controlled the . tape recorder, stopping the presentations temporarily if the subject needed a longer time to respond between stiJmJli. I i The following six experimental conditions were presented in this study: . I 0% time compression at 16 dB SL 30% time compression at 16 dB SL. 60% time compression at 16 dB SL 0% time compression at 32 dB SL 30% time compression at 32 dB SL' 60% time compression at 32 dB SL The values for the 16 and 32 dB SL conditions were determined from each subject's SRT score. I Each age group of subjects received presentations at both 16 and _ 32 dB SL. In addition, each subject in each of the groups received two time compressed conditions, either 0% and 30% or 0% and 60%, so that each list of the WIPI was used a maximum of one time per subject. The 0% condition was always presented first to each subject, as this 23 is the clinical procedure generally used. Each subject received two lists of the WIPI at the 32 dB SL condition prior to the presentation of lists at 16 dB SL. Order of presentation of the four test lists was rotated. . Individual. data sheets were completed for each subject listing basic identifying information , SRI‘ scores , experimental conditions pre- sented, and scores for each experimental condition. (See Appendix C) A response sheet was also completed for each subject, indicating correct responses and incorrect responses (See Appendix D.) The mean percentage scores for each of the three Subject groups under each condition of time corpreSs ion , age and sensation level were computed. Scores obtained by right and left ears were cmpared to see if any differences resulted. The ten most frequently missed words for each age group were also determined. Data were compared with previous investigations . CHAPTER III RESULTS Results of the study showed that scores decreased as the per- centage of time colpression increased. The 32 dB SL presentation resulted in better scores than presentations at 16 dB SL. Higher scores were found as age increased from four to eight years. Minimal right versus left ear differences were found , but no consistent trends were observed. Scores by list were compared, and the ten most. fre- quently missed test words for each age group were computed. The results of the Study can be found in Tables one throughisix. Time Compression and Sensation Lavel As the rate of time compression increased from 0% to 60%, the mean percent scores decreased wider both sensation. levels (See Table l) . For both sensation levels, only a. slight decrease in scores was noted at 30% time compression. However, at 60% time cotpression, the mean ‘ scores were generally much poorer , particularly at the 16 dB sensation level. _ . - _ Scores increased at all three time compression conditions as the Sensation level was increased from 16 to 32 dB, a finding similar to that of Beasley, Maki, and Orchik (1975). However, Beasley et al. found that there was a major improvement in scores at the 60% time 21} 25 a”: new 98 ”.8 .15 93 ”.3 ad... {a 93 9.6 35 .13 m Boa m.mm . m.mm m.:m m.mm o.mm s.mm m.um e.sm m.sm 5.5m m.sm m.sm V m m.~m o.mm m.~m m.mm m.mm o.mm Am.mm H.mm m.mm m.mm n.mm m.mm m m.Hm 5.3m. «.ms . o.~s m.es s.mm c.1m m.mm o.~m «.0m 1.0m a.om : H38. ”Ema “£3 Boa “Ema £3 1.5.2. Ema t3 HES. 9&2 £3 Hmpoev_ .mmm.. .mmm . mmw mm< m noun mama—00 mafia Am me am H.mm :.~m m.mm o.me. m.:~ m.be o.mm “.mm «.mm «.5m «.5m 3.5m ‘.m Hayes m.mm :.mm_ m.om «the o.mm s.mm :.am m.om o.om m.om m.mm m.~m m m.:m «.mm :.:m o.me c.55 m.:e m.mm . :.sm m.mm o.om «mam m.mm m o.me p.ms m.ms o.mm . m.Hm H.mm «.me m.mu m.me m.om m.om H.Hm : HBBpfiE £3 fifieufié t3 QSBufiE t3 fifiaufié t3 3 , 0 Happy .mmm .mmm .mm gflwwggv 95E”. . Aw MU mH . . ..magnifiehummfimH 9mm gamma can. ”Ewen now mwmvcwgmm c3383. . .a mummd mwm some now NEE man. so Page 5.” 8903 3.333335... :82 25 corpressicn condition with an increase in sensation level, whereas theresults of the present study indicated a similar increase for all levels of time compression. The mean difference scores between sensa- tion levels for the three rates of time compression and each age group are indicated in Table 2. ' . H TABLE 2. Mean difference scores on the WIPI between 16 dB SL and 32 6 dB SL for each age group and each time compression condition of the present study (P). The Beasley et al. (B) and the - ' Sanderson and Rintelmann (8) results are also shown for comparison purposes . Time Compression ’08 -308 8085 §.. 3" E. a. :3.— .P. .8. E 2 Age . ' v. . 13.0 - 9.3 . 4-' .- . 14.8 . - I - '7‘.o 5 3.3 11.2 5.8 - 9.6 _ 8.8 _ - 17.8.12.8 8 ‘ 3A. 6.8 8.8' - 8.8 '7.2 - 8.8 5.3 The mean scores obtained in this study were slightly poorer than those of Sanderson and Rintelmann (1971) but were somewhat better than those of Beasley et al. 0(1975). The greatest mean score differences between the present study and the Beasley et al. study were found at 60% time compression for both sensation levels. The mean scores associated with the several levels of time compression, sensation level, and age can be found in Table 3 . 27 , .onm new o-m .ou: ”euspm pcmmugm osu_ncm mane nam_~uo .a-:.N.Hm pm smammom were new mum 61m "8%. $30.93mmmgghnomwnommfiggmnmomfiafimonommwmgoge. 9mm 9mm 93 98 9mm 93 w 3.3. m.~m m.mm u m.me c.Nm. . o.~s o.m : was m.um 1.0m . m.mm o.~m u c.1m w.am - mom s.sm m.um n.ea m.mm m.:m m.em ~.am «.mw e.am we , . , Gounmmwnasoo mag m m m m m m _m _m m umu. .Jma .mn» .8m< mm_mu am 93 98 95 93 9.2. e H309 ~.se _ a.we u c.ms.. :.:m‘. u e.mo . a a: was :.om m.pm . m.mm :.Nm . «.ms . u . . eom m.om m.am m.mm o.om m.mm c.1m m.om . . p.ms . we , . counwmgeeoo mafia m m m m .m m. m, m m .mww .nw. .na. «mw< . .am.me ma .momomna somwgmguoo .Hom gm Omdm who mygmg Amy 5333 g dogwoqmm 86. on... 2: Am #8 .6388 93. .av Sm acumen” m5. 90% “a fifim am. :3 mmoohw own 90% Hoe/ma nonhuman“. 98 £038,538 can». mo coflflocoo £08 90% EH2 gt. :0 macaw, Magma . com: . m 59%. 28 EffeCt ‘of Age As indicated in Table l , mean percentage scores increased for both sensation levels and all time compression conditions as age in- creased. The greatest score differences were obtained between the four year old group and the six year old group. In general, scores for the six year olds were only slightly poorer than scores for the eight year olds. The greatest score differencebetween for and six year olds occurred at 60% time compression under 32 dB SL. while the greatest difference between six andeight year olds was found at the t 60% time carpression condition under 16 dB SL. This trend of differ- - ences between the four and six year old groups and also the six and eight year old groups at both sensation levels-was sinfiJar to the‘ results of Beasley et al.* I i I Score differences between age groups in the present study were generally less for all age groupings than those reported by Beasley et al. Table ll indicates score differences between age groups for the present study and as reported by Beasley et al. ' Ear Differences Mean scores obtained from presentations of the WIPI to both left and right ears are found in Table 1. No consistent ear advantages were fOImd forany age group. *Beasley et al. did not present the stimuli at a 16 dB sensation level to the four year old group. 29 TABLE 14. Mean difference scores on the WIPI in percent between ages 1+ and 6 and between 6 and 8 for each time compressed condi- tion. Beasley et al.'s (l975) values are indicated in ( ). ~‘IE’M * r‘-g-?r‘z -._. 16 dB SL 0 Age; Hand 6 '6 and 8 Time Compression f 0% 9.1 .9 (7.2) g 30% 9.3 - 1.81 (5.2) 60% ‘10.9 . 11.2 (10.6) Total E? 9.7 H.6 9.0 32 dB SL 553 "Hand 5 "Sand 3 Time Compression 0% 5.5 (8.0) 1.8 (2.8) 30% 9.3 (11.2) 0.3 (9.0) 50% . 16.8,(1u.0) .3.7 (0.8) Total E 10.6 (11.0) 3.3 (0.0) 3O LiSt Differences and Analysis 'Of Errors Mean scores for each list for all groups at each sensation level and time compression condition are included in Table 5 . In general, 1 scores obtained with each list were similar. However , overall mean t scores obtained from List IV were slightly lower for both sensation 1' levels, particularly at 60% time compression. Beasley et al. also noteda similar trend for List IV. Table 6 indicates the ten most frequently missed words for each age level across all levels of time compression and boflu sensation ’ levels. -It was noted that List IV contained at least two times ‘as many of the host frequently missed words when compared to each of the other three lists.' ' I. . For eachiage level, each group of the ten most frequently missed words was analyzed to determine what percentage of the total errors i-t comprised. For the four year old group, the ten words with flue i greatest total errors accounted for 61.75% of all, errors. For the six year old group, 35. 596 of all errors occurred within the ten most fro-r quently missed words, and for the eight year old M #7. 596 of all errors were found within this group. 31 .m.om new 3.8 mi .93 98 was. is m. s33. n.3m. m.mm,w ss ~.m>_ m .m.:m. m m.sm .ss o.mw m alum. om 0.1m . >s m.mm m.mm m 0.0m _ as o.mm e s.mm :s s.mm ss m.om «a m.~m sss :.mm m.sm. m o.mm ss s.mm e m.~m .ms m.mm m m.mm sac o.mm ss 5.0m m.sm m 0.3m .ss m.mm ss o.~m m m.mm m o.mm :N m.mm s smss .m. Am in .m I.) m “M is NM..|LMM Mm sm NM .u.sw. Mm saves sow son so . . .cosmmmgasco mesa sm mu um 98 was was «as. 0.8. .25 new 9% e s38. m.ee o.ee V: o.mm as m.de .5 m.me ms m.om : so.mm ma s.mm >s s.mm m.mm e .s.sm ms m.sm m m.mm m o.mm m m.mm :m «.0m sss m.ms m.mm m 0.3m m. m.ms m e.wu ms .m.mm e s.mm om m.mm Hs m.om .m.mm : o.mm. m b.5s : o.mm is .o.em : o.mm .mu o.mm s u. n. .. .. .. .. .._ .. .. .. .. .. .. .. .pmss m n m : m.|:._c m a m.||u a. m a m .1: c m smuoe sow . . . sow . so . c3385 meg. Am mo 3” l' ...sm me as ea mesa gmms m new m gum Ame sespm .Hm pm hoammom mfi. Rom can any gm #53.an may 90% nousvdocoo gowmwemeoo 959 £08 . Hm omega—co mmbouw emu Sum 90% EH3 05. mo pm: some now, monsoon Powaaoo #5093 new: .m 59E. 32, TABLE 6. The ten most frequently missed words on the WIPI at all levels of time compression and both sensation levels for _ each age group. ..................... 1+ Year Olds Word ‘ List ‘ Times Missed Times Presented '% Missed Crown 3 22 30 73 Spring 3 21 30 70 Gum l} 21 30 70 Wing l 20 30 66 Beet '4 19 30 63 Bowl 2 18 . 30 60 Pear 1+ 17 30 56 Bow '4 17 30 56 Red 2 ' 16 . 30 53 Pan, 1 16 30 53 6 Year Olds Bowl 2 15 30 50 Beet ll ‘ 15 ' 30 50 Gum 1+ 12 30 40 Bow '4 12 30 I+0 Pan 1 ll 30 36 Pear l} 10 30 33 'Lip' ”a 9 30 30 Wing 1 9 30 30 Spring 3 8 30 26 Box 3 7 30 23 8 Year Olds Bow '+ , 14' 30 1+6 Pear 1+ 11 - 30 36 Crown ' 3 ll 30 36 Spring 3 ' 10 30- 33 Gum l} 10 30 33 Lip ' 1+ 10 30 33 _Mouth l) ' 9 30 , 30 Bee 1+ 8 30 26 Broom 2 8 q 30 26 Bowl 2 . 7 30 23 CHAPTERIV _ DISCUSSION Results of the present study indicated that for all three age groups tested, intelligibility decreased as time compression increased. In addition, scores improved as a function of increasing sensation level and increasing age. .' No consistent ear effect differences were found. In determining the ease of each list of the WIPI, it was found-- that lower scores were. often associated with List IV, and furfluer, of. the words missed most frequently' by each age group, a greater peroentage was contained in List IV. Caution should be used in interpretation of list results, since the number of subjects per list in each time can- pressed condition is small. . Overall, the scores and trends found in the present study were similar to those reported by Beasley, Maki and Orchik (1975). The present study differed somewhat in procedures from the Beasley et al. study. in that a different male speaker was used to record the test stim- uli , testing was done under earphones with only one ear receiving the test stimuli (as Opposed to sound field), and four taped practice itens , preceded each test list. In addition, each of the two higher time com- pressed conditions was preceded by a 0% compressed condition, whereby the first presentation was always at ‘32 dB SL, followed by‘ either the 30% or 60% compressed condition at 32 db SL. The last two lists .33. 3'4, received by each subject were presented at 16 dB SL at 0% time com- pression followed by a 3096 or 60% time compressed condition. Time Compression 'and Sensation 'Ie'Vel For each age group at each sensation level presented , highest scores were obtained at the 096 time compressed condition, with a slight decrease at 3096 time compression and a major decrease at 50% time can— pression. As sensation level increased from 16 dB to 32 dB, an increase in scores was observed at all levels of time compression for each age The scores obtained in this. study were similar to those of Beasley et al. (1975), but were somewhat higher under the 30% and 60% time compressed conditions 'at 16 dB SL and 5.0%.1'2132 compressed condition at 32 dB ISL. _ . The improved scores of this study .were a. probable result of the. procedure in which. the test stimuli were presented to the subjects. v Prior to each test list four taped practice items were presented at the same rate of compression as the test list to follow. Presentations of . practice items allowed the subject time to, adjust to the time compressed rate and the sensation level of . the stimuli. Each subject received a. 0% time compressed condition prior to receiving either the 3093 or 60% condition at each sensation. level, and, in addition, all subjects re- ceived two 32 dB SL conditions prior to receiving any lists at 16 dB SL. These procedures resulted in the easiest conditions being presented first, then progressing to more difficult conditions at a lower sensation level. Wren—“m ct...’-_11 35 The procedures allowed the subjects additional time to become familiar with the task prior to receiving the more difficult listening conditims ._ Beasley et al . did not hold constant the sensation level or time com- pression rate presented initially to each subject, this the nest dif- ficult sensation level and highest compression rate were sometimes the first condition presented. Effect ‘iof Age As age increased, intelligibility secres metevea for all time compression conditions. and both sensation levels . Results chewed that both the eight and six year olds. achieved higher scores at re more difficult 16 dB sensation level than the four year olds at the easier 32 dB sensation level. The exception to this trend was found at the 0% time compressed condition where four year Olds at 32 dB scered equivalent to six and eight year olds at 16 dB SL. filie poorer scoring trend by the four year olds may indicate that younger children who have less language experience need the temporal redundancy (“9f non-compressed words to achieve maximum intelligibility. In comparing the results of the 0% time compressed conditicns “' wifil ' those results obtained by Sanderson and Rintelmarlfi (1971) , those scores reported by Sanderson were higher at both the 16 and V 32 dB sensation levels. A similar result, in comparison to Sanderson and Rintelmlafin's“ findings, was found by Beasley et al. (197.5% . Two possibilities were suggested by Beasley et a1. (1975) for file higher scores obtained by Sanderson and Rintelmann. One possibility 36 for the differing results is the manner in which the test stimuli were generated. The tapes used in the Beasley et al. and present study were processed at 0% time compression using a time compressor, resulting in the presence cf some compressor noise. The Sanderson and Rintelmann tapes were not generated using a time compressor. An investigation using tapes generated by both procedures to achieve a 0% time compressed condition ‘ could be undertaken to determine if intelligibility scores are affected by the manner of stimulus genera- tion. ‘ _ 4 ' A second and more likely possibility suggested by Beasley et al. was the effect of differences in mean SRT scores. Table 7 shows the mean SRT scores for comparable age groups in the present study as com- pared to those of Sanderson and Rintelmann and Beasley et al. SRT values for. the Beasley et al. study and the Sanderson and Rintelmlann study were obtained in sound field with Speakers at 0° azimuth. The SRT values of the present study were obtained under earphones. The mean SRT scores obtained by Sanderson and Rintelmam'were higher in abrest all instances than those of either the Beasley et al. study or the present investigation. .. I ‘ Dirks , Stream and Wilson (1972), in reviewing the literature on - speech audiometry, compared Speech reception thresholds for Spondees obtained under earphones and in sound field. Results of the studies selected indicated that SRTs obtained under earphones were usually 3.6 dB poorer than those obtained in sound field when the speakers were placed at a 0° azimuth. Thus, it would be expected that those 37 TABLE 7. Mean SRT scores in dB according to age groups for the present study, Beasley et al. (1975) and Sanderson - and Rintelmann (1971). " Ages * 1*. ‘ ’9. £3. Sanderson and I Rintelmann 12.8 (6 to 18) 8 (21:0 10) u.5 {-2 to 12) Beasley et al. 6.3. {-2-to 16) ‘ 2 (-2 to 8). 2.3 {-2 to 10) Present Study 9.5 (o to 20) 6.3 (2 to 12) ,5 ' '(-6 to 12) mean values for SRI‘s found in this study would have beenlower (better) if obtained in a sound field condition at 0° azimuth. If this trend was actually observed, the SRT values in the sound field corriition would have been more similar to those found by Beasley et al. , suggesting that the Sanderson and Rintelmann procedures for obtaining SRI‘s maybe clinically inapprOpriate. - h - Beasley et al. also suggest that those differences in SRI' scores may be the result of procedural differences in obtaining the SRT values. 'Ihe present study followed the saneprooedures as Beasley vet al., ini-' tiating presentations of the Spondees at an intensity level of approx- imately 30 dB HL. Intensity levels were decreased in it dB steps fol-.- lmirg word presentations . Initially, two words were presented at each intensity level until the point where each subject missed the first word. From that point a maximum of four words was presented at each intensity level until the lowest. point was reached at which the subj ect. could repeat 50% of the words presentedn Sanderson and Rintelmann's 38 procedure began with an initial intensity level 10 to 20 dB above the estimated threshold and decreased in 2 as steps. Four words were pre- sented at each sensation level. Thus , the Sanderson and Rintelmann ’ . procedure would allow for a greater number of word presentations, pos- sibly increasing the likelihood of subject fatigue and ultimately re- sulting in a higher SRT value than the actual value. Ifthis were true, then the sensation level of the test word presentations would actually be higher than the level indicated. By using the SRT procedures of the present study and presenting test items at higher sensation levels it could be determined if the difference between intelligibility scores . in these three studies was a result of differing SRI' scores. Bar Differences It has been recognized that a cerebral hemisphere dazninance exists for smech processing. Research using dichotic listening tasks has shown that verbal material is better perceived by the right ear- .left hemisphere (Kinnira, 1961; 1963; Shanlmeiler, 1966;3tuddert- Kennedy and Shankweiler, 19705 , whereas non-verbal environmental somds. were found to be nore accurately perceived by the left ear-right hemisphere .(Knox and Kimura, 19:70). Since contralaterel auditory path- ways to the cerebral hemispheres have been shown to be stronger than ' the ipsilateral pathways (Kinme, 1961), the results ‘of this previous researdl inply a left cerebral hemisphere dominance for verbal processing. . Recent research has suggested that ear advantage is less evident . i when monotic speech; tasks are presented (Dirks, 1961;) . Dirks presented filtered phonetically balanced mrds in both dichotic and monotic 39 conditions to normal hearing listeners . A significant right ear advantage was found only in the dichotic situation, with a greatly reduced advantage with the right ear observed in the monotic situation. The present study , involving a mnotic task , resulted in no consistent ear advantages. The greatest difference in ear scores was a right ear advantage observed at a 32 dB sensation level under 60% time compression for the four year old group. However, at the same time carpression rate and at 16 dB SL, a slight left earadvantage * was observed for the four year olds. No explanation is offered for this occurrence.- Additional researchis warranted to study ear differ- ences with children under time conpressed conditions, as no research I on this topic, other than theppresent study, has been reported? ‘ . Although no additional information on ear differences under time compressedconditions with children is available, Beasley, Sclmimrer, and Rintelmam (1972b) and Beasley, Fornan and Rintelmarm (1972a) ‘ reported minimal ear differences for adults under time compressed conditions using a mnotic Speech task. List Differences and Analysis of Errors Overall mean scores for List IV were somewhat lower than the other lists of the, WIPI. The. remaining three lists resulted in similar mean scores. In computing the ten most frequently missedwords for each age groxp, it was found. that List IV contained at least twice as many of the most frequently missed words in canparison to the other three lists. List IV, therefore, represents the most‘difficult speech dis-l crimination task of the ,four WIPI lists and may be expected to result ' M0 in poorer scores . Several errors resulted from apparent oonfus ions or non-recognition of the drawings of the WIPI. For example, the test word "skirt" appears on the same plate as the foil picture of a girl wearing a dress. Subjects frequently pointed to the skirt of the girl's dress rather than the . pictured skirt. Across all age levels the selection of "girl" comprised 66.6% of the total errors on the test word "skirt.". A picture of a glass of milk, apparently representing a dish for some children,qappears as a foild on the plate with the test word "dish." Again, the foil accounted for a high percentage of the total errors on the test item. In presenting the WIPI, problems with items associated with such confusims may be alleviated by asking the child to repeat the word heard, if the pictures on the plate appear to be ambiguous. Amore. . comprehensive task would be to have the pictures currently in use ' Clinical Implications . Results of this study indicate that, in order to achieve optimal scores on time compressed conditions of the WIPI, several procedures should be followed. Practice items should be administered at. the same rate of time canpression as the test stimuli that follow. Higher sensation levels should be presented before the more difficult lower - sensation levels, and a 0% time carpressed condition should precede higher compression rates at each sensation level presented . Deviations nu from these procedures may be expected to produce lower scores. For the nomal hearing population of this study no ear advantage was noted; therefore , presentation of the test stimuli could be to either ear with minimal intelligibility score differences. Results similar to those of this study, in terms of intelligibility scores, were reported by Beasley et al. (1975). Test stimuli wére pre- sented in sound field rather than mder earphones as in the present study. Particularly for younger children , sound field presentation would be recommended as same of the younger, children in the present ' study showed an aversion to wearing earphones . i ' 0f the four WIPI lists, List IV was the most difficult and re- sulted in the lewest mean scores. This was particularly evident at 30%,and 60% time cmpression rates at the more difficult 16 dB sensation- level. Therefore, if a slightly more difficult speech discrimination- measure is desired in oarparism to the other test lists, List IV could ' be presented. . ' The most frequently missed words overall for each age group were computed. Future research efforts may wish to compare word errors by sensation level, time coxtpression and 'age in addition to total overall The present study presents narrative data for normal hearing white children on time carpressed conditions of the WIPI. Additional studies are needed to supply comparable data for other pcpulations of , ‘ children, such as the learning disabled, brain damaged, and hearing- impaired , to provide infornetion about the speech discrinfination ‘3'?. ' - ‘ fimH—x-Db a: z' ‘ . M2 abilities of these populations under time compression. (Imperative information is needed to distinguish the performance of other populations of children from that of normal hearing children. Ear advantages should be investigated with other populations to deter— mine if they exist. Future research efforts should be directed at . determining for what populations of children the time compressed WIPI would be an effective diagnostic tool. CHAPTER V SUMMARY The purpose of this study was to determine the effect of time coupression upon normal hearing children's intelligibility of a closed set speech discrimination measure. Stinuli were presented under ear- phones at'two sensation levels. The stimuli used in this study were the words fran the Word Intelligibility by Picture Identification (WIPI) speech discrimination measure. Stinuli were processed using a Lexicon Varispeech III-time carpressor. Ninety normalhearing childrenwerethesubjects ofthestudy.- , The results of the study provided normative data on the Wcrd ‘ Intelligibility by Picture Identification 'speech discrimination measure for normal hearing children aged lb, 6, and 8 years. ' Data were - included for 0%, 30% and 60% time compressionand 32'dB and 16 as ‘ sensation levels. - ‘ . ‘ Results stmed that dismnfination scores decreased as the per-- centage of time compression increased. Also, better scores resulted as~age and sensation level increased. Minimal right versus left ear differences were found, and no consistent trends were observed. 0 Scores by list were compared, and the ten most frequently missed test words for each age group Were cmputed. . 6 Clinical application of the procedures was discussed. Results were conpared with results of previous studies. 'lt3 . APPmDIcss APPEme A lPRACI'ICE mans BY LIS'I" nu- ' PRACTICE ITEMS 2 O at 3 . Glass l} . Grass 1. Rat 2. .Cap ' 3. Bat u. Glass . LIST THREE 1. Grass -2._ Rat 3. Cap (1+. oat LIST FOUR 1. Cat 2. Grass 3. Eat 1+. Rat . APPENDIX B CALIBRATION PROCEwRES AND INSTRMNTATION WERATION PROCEDURES AND INSTRUMENTATICN Audiometers used during testing procedures were calibrated to meet those standards established by ANSI (1969). 133me MODEL 15c CLINICAL Auniomi 1. INTENSITY ourwr cf the audiometer was calibrated for each test earphone (TDH 39 with MX l+l/AR cushions) by using a Bruel and Kjaer Type u152 artificial ear with a Bruel and ,Kjaer -'Iype' ulna microphone attached to a Bruel and Kjaer sound level meter Iype 2201+. HARMONIC DISTORTION . was calibrated using the test earphones with a Bruel and Kj-aer 'Iype l+152 artificial ear with a. Bruel and Kjaer Type #1“ microphone attached to a Bruel and Kjaer Audio Frequency ‘ Spectrmeter Type 2112. . GRASON-STADLER MODEL 162 SPEECH AUDIOMETER l. A'ITENUATOR LINEARITY was calibrated by directing a 1000 Hz tone from an Ampex AG 600-2 tape recorder into the Speech audi—- ometer. The attenuator of the audiometer was initially set at 100 dB HTL and has" subsequently attenuated down in 10 dB steps. The signal output from the audiometer was directed V through the test earphone (Tm 39 with MX “llAR cushions) to .a Bruel and Kjaer Type [.152 artificial ear with a Bruel and Kjaer Type 11.1% micmphone attached to a Bruel and Kj aer Type 2112 AudioPrequency Spectrumter.‘ .'+S '46 ELECTRICAL NOISE was calibrated by using the same instr'ua mentation as indicated for attenuator linearity. The signal output from the tape recorder was directed through the speech audiometer. Readings from the Spectrometer were taken first with the tape recorder on with no signal being played and then with a lo 00 Hz tone being played. With the attenuator of the audiometer at loo dB HTL, the dB SPL level when there was no 1000 Hz signal output was required to be so dB SPL below the reading for the 1000 Hz_tone output. 3 . ACOUSTIC FIDELITY was calibrated by directing pure tones of 200, 300, I400, 700, 1500, 2000 and L$000 Hz fran a Hewlett Packard HZOHA Oscillator into the Speech audiometer. messi‘ie test earphone, artificial ear, microphone, and SpeCtruneté'r as- was indicated for attenuator linearity were also utilized ' for this calibration. The spectrometer reading for each of the above frequencies could not differ from the reading of the 1000 Hz tone by more than ten dB to meet calibration- standards. INTENSITY OUTPUT was calibrated by directing a 1000 Hz tons ‘ fran the Ampex .AG 600-2 tape recorder into the speech audi-i ometer. The VU ineter of the audiometer was peaked at '0 dB and the HTL level of the attenuator was set at 50 dB . Again using the same calibration.‘ instnimentation, the SPL output? could not differ from the established standards by more man 3' dB. ' V APPENDIX C INFORMATION SHEET. 07 SUBJECT NO."' INFORMATION SHEET DateofTesting': """""""""" Sex: M F Age: A 5 8 Nana: ................................... Birthdate‘: ....... C.A.' . .......................................... P ts:......................-.....I .............................. ' . 'HEARING'SCREENING (20 dB RE: ISO 1964)- RE 125' 250" 500" 1000' 2000" uooo ~ 8000" LE 125 ‘ 250" 500" ' 1000‘“ 2000" 0000" 8000 ‘ .ARTICULATION ERRORS NOTED Distortions Substitutions Omissions TEST EAR: Right left .SRT = . dB 16 dB SL = 32 dB SL0: "TIME COMPRESSED CONDITIONS RECEIVED ‘ 0% and 30% I ' 0% and 60% ' LIST ORDER RECEIVED: ' 123a 23ul' 3u12 0123 ‘WIPI SCORES: _ 16 dB: 0% List . 30% LiSt ‘ 60% LiSt 32 dB: 0% I List 30% List 60% List ‘ APPENDH D WIPI SCORE SHEET SUBJECT NO. WIPI SCORE SHEET Name“ DOB Date List Order: 123l+ 23lll 3'412 H123 Ear: R L %: 0, 30 0, 60 ’ LIST ONE LIST TWO LIST THREE LIST FOUR SL" - SL"" 51'. ...... SL""' TC' . TC' TC ...... TC' . SChOOl;_’__ broom_'_'___ moon ' ' ' ' Spoon—I sunke_'____ coat"' coke'” goat" f0x' socJHocH 51} 88 .8 88 N 88 H 88 8 H 8 8-8 8 8N H 88 V 8 88H 8 N8. . . N 88H H 8 8-8 8 8N N . 88H .H N8 8 88 8. 88 8 . 8H _ .8-8 8 N H 88 . 8 88H 8 N8 V N N8 H NH .8-8 8 8N 8 88H N. 88 H . 88 8 88 8 8 8-8 2 8N 8 88 8 .88H N 88 H 88 8 8 8-8 2 NN 8 88 8 88H N. 88 H 88H H 8 8-8 8 8N 8 88 8 N8 . N 88 H N8 8 8 HH-N. 2 8H 8 88 8 N8 , N 88H H 88 H 8H 8-8 .8. 8H N 88 H 88H . 8 N8 . 8 .88H 8 . 8 N8 8 8H N 88 H 88H 8 88 8‘ 88 H 8 8-8 8 8H 8 88 N 88H . H 88H . . 8 88 8 8H 78 2 8H 8 88 . N 88H H 88 8 88 H 8 .8-8 8 8 H 88H 8 88H 4 8 88H . N N8 8 8 8-8 8 8 8 88 N .88 . H . . 88 8 4N8 8 8 HH-N. z 8 “EH 888 . pmHH mm _ . 8.83 mg ..2 88.3.: Masha 888. 38:0. 888 8 888.388 H8 88 N8 H8 88 8H Pom-Coo 950.38 88.8 898.com coflhfififim-B 888088188888. 5888888850 .8888? 888. can“ 88. .888. BE. .85 Bfimowfi 983.. 830.8888 8 pom. 386 HusugchH . . LIST OF was _ LIST OF REFEREMZES . Aaronson, D. , Temporal factors in perception and short term mennry. Psychological Bulletin, 67, 130-11!!! (1967). Beasley, D., Forman, 8., and Rintelmann, W. , Perception of time-con- pressed CNC monosyllables by normal listeners. Journal of Auditory Research, 12, 71-75 (1972a). Beasley, D., Maki, J. and Orchik, D., Children's perception of time- canpressed speech on two measures of speech discrimination. Journal of Speech-and Hearing Disorders (In press). Beasley, D., Schwirmuer, S., and Rintelmann, W., Intelligibility of time- compressed CNC monosyllables . Journal of Speech and Hearing Researdh, 15, sun-350 (1972b). Beasley, D. and Shriner, T. , Auditory analysis of temporally distorted sentential approximations . Audiology. Journal of Auditory Communication, 12, 262-271 (1973). Calearo, C. and Lazzaro'ni, A., Speech intelligibility in relation to the speed of the message. laryngoscqae, 67, Lt10-419 (1957) Daniloff, R. , Shriner, T. , and Zemlin, W. , Intelligibility of vowels altered in duration and frequency . Journal of the Acoustical Society of America, an, 700-707 (1968). de Quiros, J. , Accelerated speech audianetry and examination of test , results (Trans. by J. Tonndorf). Translations Beltane Institute of Hearinq Research, No-17, Beltone Inst1tute of Hearing ' Research. Chicago—(1964) Dirks , D. , Perception of dichotic and monaural verbal material and cereé bral dominance for Speech, Acta Oto—laryngologica, 58, 73-80, (19610.. Dirks, D., Stream, R. and Wilson, R. Speech audiometry: earphone and sound field, Journal of Speech and Hearing Disorders, 37, 162- 176 (1972). Fairbanks, G. , Bveritt, W. , and Jaeger, R. , Methods for time or frequency compression-expansion of Speech. ‘ Translations I.R.B.-P.G.A. , AU-2, 7-12 (195%). , ~. Fairbanks, G. Guttman, N., and Miron, M. , Effects of time compression upon the comprehension of connected Speech. Journal of _Speech and Hearing Disorders, 22, 10"19 (1957a). 55 56 Fairbanks, G., Guttman, N., and Miron, M., Auditory comprehension of repeated high-speech messages. ‘ Journal 'Of Speech and Hearing Disorders, 22, 20-22 (1957b). Fairbanks, G., Guttnan, N., and Miron, M., Auditory comprehension in relation to listening rate and selective verbal redun . ' ‘Journal of Speech and Hearing Disorders, 22, 23-32 (1957c). Fairbanks, G.,and Kodman, F. , Word intelligibility as a function of time compression. Journal of the Acoustical Society of Air-erica, 29, 636—6110 (1957). Fletcher, H. , Speech and Hearing in CommmiCations. Chapters 15-19. New York. Van Nostrand (1965). Foulke,E . , Comparison of comprehension of two forms of compressed speech.’ Journal of ExceptionalChildren, 33, 169-173 (1966). Foulke, 2., Amster, c., Nolan, c., and Bixler, R., The canprehe'nSion of rapid speech by the blind. Exceptional Children, 29, 13'4-1‘1-1 (1962). Garvey, W. , The intelligibility of speeded speech. Journal of Experi- mental Psychology, #5, 102- 108 (1953). J erger, J. , Audiological manifestations of lesions in the auditory nervous system. Laryngosccpe, 70, #174125 (1960). Kimma , D. , Cerebral dominance and the perception of verbal stimuli . . Canadian Journal of Psychology, 15, 166-171 (1961). Kimura, D. , Speech lateralization in young children as determined by an auditory test. Journal of Comparative Physiological Psychology, 56, 889- 902 (1963). Klumpp, R. and Webster, J. ,Intelligibility of time compressed speech. Journal of the Acoustical Society of America, 31, 265-267 (1961). Knox, C., and Kimura, D., Cerebral processing of nonverbal sounds in boys and girls.’ Neuropsycholcgia, 8, 227-237 (1970). Konkle, D., Beasley, D., and Bess, F., A study of time-compressed speech with an elderly population . Paper presented to the American Speech and Hearing Association, Las Vegas (1971!). Kurdziel, S. , and Noffsinger, D., Performance of cortical lesion patients on I40% and 60%. time compressed speech materials. Paper pre- sented to the American Speech and Hearing Association (1972). 57' Lee, F. , Time cOmpression and expansion of speech by the sampling methods. Journal of Audio Engineering Society , 20, 738- 7H2 (1972). Luterman, D., Welsh, 0., and Melrose, J ., Responses of aged males to time—altered speech stiJmili. ’ Journal 'of Speech and Hear1ng "ResearCh, 9, 226-230 (1966). Miller, F. and Licklider, J. , The intelligibility of interrupted speech. Journal of the Acoustical Society of America, 22, 167-173 (1950). Ross, M. and Lem-an, J, A picture identification test for hearing- d children. Journal of Speech and Hearing Research, 13, Hist-53 (1970) Sanderson, M. and Rintelmann, W. , Articulation functions and test- retest performance of normal hearing children on three speech discrimination tests. Paper presented to the American Speech and Hearing Association, Chicago (1971). Sharflcaeiler, D. , Effects of temporal lobe damage on perception of di- chctically presented melodies . ‘ Journal of Comparative Physiological Psychology, 62 , 115-119 (1966) . Sticht, T. and Gray, B. , The intelligibility of time-compressed words as a frmcticn of age and hearing loss. Journal of Speech and Hearing Research, 12, HUB-9% (1969). Studdert-Kennedy , M . and Shankweiler , -D. , Hemispheric specialization for speech perception. Journal of ' the Acoustical Society of America, H8, 579-59“- (1970).- Tillman , T. and Carhart, R. , An expanded test for speech discrimination using CNC monosyllabic words (N. U. Auditory Test No . 6) ' SAM-RT—BB- 55. (1966). . Utley, J, What's Its Name. Urbana, Ill. :University of Illinois Press (1951). o O. . ' ‘ o' .- . a - . O .' ' . ." 8 .- a ,‘ ‘ ~ . .‘ ' .8 _ - .. _ . .' .- . " I .' ,- . u .r u o ' I I - ' N _ ' , c. ’ a 8 ., .- 8'. . ‘ . 8 . . ,. ‘ 8 . 8 . u . .I l . 8 ,. n . .' ‘ .8 . " a ‘I ‘ v. ' .8 ' ' . . . .. .. - . . I a . . ' -' 8. ' . u . . ‘ .' ~ 8 8 . ' c ..- . - ‘ O1 8 . . _ .- . . . 1' ’ . . . ‘- l .0 . I ' . .- . o . ’0 N ’ . o _ c - ‘ I ' 8 . . ' . v I - ' - u -o . . . . . _8 1 8 ~ . 8 8 " . 8 8 ' 8 . o o .. p ' . , . . 8 u '- ‘ 8 o v '. . .' ~ c .' - . . ' ’ h 4 . I - I I. . . . o g. '. _. . . ,- . u ' . 0. . - .o ‘ . . .. a .- --- . . D. _ n n . " ' n " v 8 ‘ . . u . - u 8 . ’. 8 0. . .‘. .- .ca . u . -0 8 o 8 - O c .- a 8 . . . n ' .r 4 . . ' . n ’ - . 8 a n _ '- . . ,- . . '. .- u . ' . . l ' . . I . ' . - . I .. ' .- 8 u _ ~ 8 ‘ .I o ' . . 8 . . . v , ' . 8 . . . u ' .' ‘ . .c u .. ' n 8 . ‘ . . ' | ‘ . I. ' . ._ v I -" . ' ' .. .. . . I ' . v . . . .. c - 4 . l ‘1 . . u _ c . . \ \ ~ ! c _ . . o. ' .. .1 i . l . '.. . ' . _ . a a . . ’ ‘ . ' ' ' . .' . . u. ‘ ' I.“ . . . 1' ' I ' ' . 7 - . . . . ' ‘ . . . u .,o 4 ... . ' .' .8 ‘ .- . .' ‘ .- .r . , I h . . . ' I. . . ' ’ 8 - 0 l. . I o ' n. ’ .8, ' o _ '. ..- . . . l' .- . ' . I o ' . .. . . ' I l . - .a° . .0 . O l . 1 . ‘ ’ . . o - o . ' .' o ". . . . ' ' . . a . .. n , - , " ._- . . . . ..l ‘ . '. . g . n . ‘ ‘ - .' ' . . ' , u ' --.‘ ' . O . ‘ . ‘ .- 8 . ' .. . . . u .. -. ...- .. ‘ . .o' . ' o. . . . ‘_ . . . _ . . l . . - . . ‘ ' . - u. ' . . . .. . . . 8 I . ' I .‘ ‘ ‘ 8.4 .. _ ‘ . . . . 8 . -' ‘ n . . . _ ‘ > . . . I .' ' . . . ' ‘ . .8 . l ‘ . ‘ . .' . .. . 8 . “‘ ' I . . . I ' . 0' . , o . ' . a ‘ .o ‘ . u . . O ”CHIC-AN STATE mm Id” 3 H"?! III N! ' N.‘ 1293 03174 75 r!!- 5, 1 i l i 7 . . _- . . n ' . - - . v o ‘ ' ' . Q - . - u ‘ . . v a I I -‘ I . . ‘ n . ' ‘ . - . -' . ’ . - " I . ‘ '- .. - . I . I . ' .8 . t 8 . ' l . .' 8 I I ' 7 . ' - . O ' . ._ ‘ - . _ ’ , ' ' . - ' ’ i . n .' u I . . I . ’ ' ’ . . 1 4 - I . u - ‘ .8 . ' n . . . . . a I .- ' . 8 .— ‘O . . - i ‘ . ‘. .- a - ‘ . n _ v . - - . . ' l o . a r, . . . ‘ ‘ . .- . ‘ l ' I . ..' . A I . . . ‘_ .' n I . a ' ' I . I I. ' c . r . . '. . . .l u . I ' . h.- . - a . . a '. . o . . . ‘ . . . . .1 n . . o . . 1 a 8 o a . . FRSITV LIBRAP' H' 1 a a I o . o , . l o r n 1 r - ES - u 8 O . l