THE EFFECTS OF BENAURAL AMflIHCATlON ON
THE SPEECH DISCREMENATION PERFORMANCE
OF NORMAL HEARING SUBJECTS

Thesis for flu Degree of M. A.
MECHEGAN STATE UNL‘E’EKSITY

Mary Katherine Flucke
19 6 2

4.1"“.

L I B R A R Y L]
Michigan State
Univcrsity

    
    
   

ABSTRACT

THE EFFECTS OF BINAURAL AMPLIFICATION ON THE
SPEECH DISCRIMINATION PERFORMANCE
OF NORMAL HEARING SUBJECTS

by Mary Katherine Flucke

The purpose of this study is to analyze the results
obtained from.nonmal hearing subjects as they responded to
the CID Auditory Test W-22 with and without amplification
by a binaural hearing aid in order to determine the effects
of amplification on their speech discrimination ability.

The subjects for this study were twelve university
students. Testing was conducted in two phases. For Phase 1
the standardized recordings of the CID Auditory Test W~22
(Lists 1A, 2A, 3A, 4A, 13, 23, 3B, and 43), were transcribed
onto magnetic tape and presented to the subjects at a level
of 70 decibels in a reverberant room. White noise at a level
of 52 decibels was employed to control the ambient noise level
of the room. Subjects were tested individually (except for
one instance when two were tested together), aided and unaid-
ed, at distances of 24, 48, and 72 feet from the sound
source. Responses were recorded by the subjects on forms

designed for that purpose. Phase 2 of the testing was

Mary Katherine Flucke
conducted in a sound-treated room to determine the effects of
amplification in a relatively noisenfree environment. The
CID Auditory Test W-22 recordings were played free-field to
each of the subjects, aided and unaided, at a level of 0
decibels without a white noise background.

The results of this study show that in both phases
of the testing subjects obtained higher discrimination scores
in the unaided listening conditions. In Phase 1 this was
true of all three positions. In all but two instances a
comparison of aided with aided and unaided with unaided
conditions showed higher discrimination scores for positions
the greater distance from the source of the sound.

Conclusions drawn from this study suggest that
normal hearing subjects perform better'cnxspeech discrimina-
tion tasks without amplification by a binaural hearing aid
in an environment of a reverberant acoustical nature with a
background of white noise and in one which is relatively
noise-free. Information, speech discrimination appears to be
somewhat easier in the latter type of environment as
evidenced by relatively higher scores obtained in both aided

and unaided listening conditions.

APPI‘OVEd by [writ/Q Ah OLE/J
I Director/] 0
\ s

THE EFFECTS OF BINAURAL AMPLIFICATION ON THE
SPEECH DISCRIMINATION PERFORMANCE

OF NORMAL HEARING SUBJECTS

BY

Mary Katherine Flucke

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF ARTS

College of Communication Arts
Department of Speech

1962

\‘fil :31"

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Chapter

I

II.

III.

IV.

TABLE OF CONTENTS

STATEMENT OF THE PROBLEM . . . . . . .

Introduction. . . . . . . . . .
Purpose of the Study . . . . . . .
Importance of the Study . . . . . .
Definition of Terms . . . . . . .
Organization of the Thesis . . . . .

REVIEW OF THE LITERATURE . . . . . . .

Speech-Hearing Tests . . . . . .
The Use of Binaural Hearing Aids . . .

SUBJECTS, EQUIPMENT, MATERIALS, AND TESTING
PROCEDURES 9 o e e o o e e e e 0

Subjects . . . . . . . . . . .
Equipment. . . . . . . . . . .
Materials. . . . . . . . . . .
Testing Procedures. . . . . . . .

RESULTS AND DISCUSSION. . . . . . . .

Re8u1ts - O I 0 o O - O O O O O O O 0
Discussion . . . . . . . . .4 .

SUMMARY AND CONCLUSIONS . . . . . . .

smary O O O O 0 O O O O 0 0
Conclusions . . . . . . . . . .
Implications for Future Research . . .

.APPENDIXE87 . .. .... . . . . . . . . . . .

A. Acoustical Characteristics of the
Binaural Hearing Aid . . . . .
B. CID Auditory Test We22 . . . . .
C. Answer Sheet . . . . . . . .
D. Raw Scores Per.Cent Correct . . .

BIBLIOGRAPHY . . . . . . . . . . . . . .

Page

\JU'IdhLOH

(I)

25

25
26
26
26

30

30
32

39
39
41
42
44
44
4s
49
so

52

LIST OF TABLES
Table Page

I. 5 Scores for Phase 1 of Testing (Reverberant
Room) 0 O O O O O O O O O O O O O s 31

II. £_Score for Phase 2 of Testing (Sound-Treated
Room) a e e e e e e e e e e e e o 3 2

LIST OF FIGURES
Figure Page
1. Mean Percent Scores for Phase 1 of Testing . 34

2. Mean Percent Scores for Phase 2 of Testing . 37

CHAPTER I
STATEMENT OF THE PROBLEM

Introduction

There is some information available about the distort-
ing effects of hearing loss upon the speech discrimination
ability of hearing impaired individuals. There is also
something known about the effects of amplification on speech
discrimination ability. Some individuals with hearing losses
are able to discriminate better with the assistance of a
hearing aid: however others, even with the increased
intensity provided by an aid, have difficulty in discrimina-
tion of speech. Audiologists have come to realize that they
may be faced with not one, but two distorting factors in
attempting to improve speech discrimination scores of hearing
impaired individuals. The first of these is frequently
associated with the hearing loss itself; the second, results
from the inability of the hearing aid to reproduce speech
accurately. Corliss mentions this problem in a discussion
of the types of distortion caused by hearing aids. Although

I

2
a hearing aid's major function is to produce gain, since the
gain is not independent of frequency, the structural relation-
ships of transmitted sounds will be altered.1 Speech sounds
represent a complicated combination of frequencies; therefore,
Kranz states that to reproduce them with as little distortion
as possible, They must have approximately the same relative
intensities that they had in the original sound. However,
each component of a hearing aid has the tendency to re—

produce some frequencies much more efficiently than it will
others.2

Studies directed toward comparing the efficiency of
monaural and binaural hearing aids (to be discussed in
Chapter II) have been made in order to learn more about
the effect of amplification on the ability to discriminate
speech. In most cases subjects for these studies have been
individuals with hearing losses. It appears, however, that

additional valuable information in this area relative to the

effect of hearing aid distortion on speech discrimination

 

1Edith L. R. Corliss, “Types of Distortion in Hearing
Aids.“ Abstracted in ASHA, 3 (October, 1961). P- 344.

2Fred W. Kranz, Hearing Aids, Sonotone Corporation,
Elmsford, New York, 1946, p. 29.

3
might be obtained by providing amplification via a hearing
aid to the normal ear, thus eliminating one distorting

factor, that of the hearing loss.

ngpgge 9f the Study

The purpose of this study is to analyze and compare
the results obtained from normal hearing subjects as they
responded to the CID Auditory Test W-22 (lists 1A, 2A, 3A,
4A, 13, 23, 33, and 43) with and without amplification by a
binaural hearing aid. From this analysis it is hoped that
it might be determined (1) if the normal hearing adult is
able to discriminate better as a result of amplification,
or (2) if the distorting effects of a hearing aid are such
as to hinder his ability to discriminate. It is also hoped
that by obtaining responses to these lists, aided and un-
aided, at three distances from the source of the sound, the
effects of increasing distance upon discrimination of
amplified speech might be obtained. As an aid to analysis
the following questions have been formulated:

1. Is there a difference in speech discrimination

scores as a result of applying a hearing aid

to the ears of normal hearing subjects?

4
2. Does discrimination of speech vary as a function
of distance from the sound source?
3. What is the trend in speech discrimination through
the conditions unaided and aided?
4. Is there a difference in the aided and unaided
speech discrimination scores as subjects were

tested in a sound-treated room?

Importance of Study

This study is important for two reasons. In the first
place, since the most important function of hearing is to
allow an individual to communicate and understand communi-
cation,1 the significance of assessing discrimination ability
in the hard of hearing individual becomes apparent. If
response norms can be established for normal hearing subjects
with hearing aids, it may be possible to determine the degree
of distortion imposed by the hearing aid by assessing the
distortion caused by the aid when applied to the ear of a
normal hearing subject.

Secondly, if it is determined that amplification by

means of a hearing aid does, in fact, improve discrimination

 

1Douglas MacParlan, “Speech Hearing Testing,“ Larynggo-
£5323, 55 (February, 1945), p. 71.

S
in normal hearing people, it may be that individuals with
jobs requiring a high degree of accuracy in their ability
to discriminate speech will be found better able to perform
these jobs through the use of amplification such as that
provided by a hearing aid. In this instance also, informa-
tion concerning the effects of distance on the ability to

discriminate with amplification might also prove valuable.

Definition of Terms

For the purpose of this study the terms used are
defined in the following manner:

§p§egh Discrimination or Articulatign Tgs§.--A test
which allows for evaluation of a patient's ability to differ-
entiate among acoustically similar sounds or among words that

contain acoustically similar sounds.

CID Auditory Test W-Zg.--A discrimination test con-

sisting of four lists of 50 phonetically balanced, one-syllable
words adapted by the Central Institute for the Deaf from

the Phonetically Balanced WOrd Lists of the Psycho-Acoustic
Laboratory, Harvard University. These words are available

in recorded form. They are presented to the subject at a

level above his Speech Reception Threshold.1

Phpnetically Balanced.--Test items in which all, or
nearly all, of the fundamental sounds into which speech can
be analized are represented. The frequency of occurrence
of these fundamental sounds is in proportion to their

distribution in normal speech.2

Speech Reception Threshold.--The sensation level at

which the patient can repeat 50 per cent of the stimulus

words correctly.3

Amplifiipppipn.--Increase in intensity--in this case.

to be provided by a binaural hearing aid.

Binaural Hearing Aid.--An instrument providing each

)

ear with a separate transmitter having its own receiver.

Normal Hearing Subjects.--Persons who are able to

hear pure tone stimuli, 250 through 6000 cycles per second

 

1Ira J. Hirsh. pp. p;., ”Development of Materials for

Speech Audiometry,“ Jgurnal of Spggch and Hearing Disorgeps.

17 (September, 1952), pp. 322-323.

2James P. Egan, "Articulation Testing Methods,” Lgryp-
gpppppg, 58 (September, 1948). p. 957.

3Hayes A. Newhy, Audiology, (New York: Appleton-Century-
Crofts, Inc., 1958). p. 111.

at a level of 15 decibels.

n z 7 h h 8

Chapter I has contained the statement of the problem
that led to this study. It has included an introduction to
the topic and an outline of the purpose of the study.

It has put forth the questions to be considered in this
study, discussed the importance of the study, and defined
the terms which will be used.

Chapter II contains a review of the literature
pertinent to this topic.

Chapter III consists of a discussion of the subjects,
equipment, materials, and testing procedures utilized in the
study.

Chapter IV consists of a discussion of the results
of the study.

Chapter V contains a summary and the conclusions of

the study and implications for further research.

CHAPTER II

REVIEW OF THE LITERATURE

Spggch-Hearing Tests

For many years the field of audiometry was limited in
scope to the evaluation of hearing by means of pure-tone
testing. With the realization that speech is the most
important thing with which hearing is concerned came a
growing interest in the evaluation of how well people hear
speech. There seemed to be, however, no way of predicting
a person's ability to hear speech from a pure-tone audiogram.1
Thus, emphasis came to be placed on the development of
appropriate means of measuring speech-hearing ability.

In this process of development it became evident
that two measures of a person's ability to hear speech are
desirable. The first of these, a quantitative measure,

indicates the level at which a person is able to understand

50 per cent of what is said to him. This level is evaluated

 

_,_ ‘—v

1Hallowell Davis, "The Articulation Area and the SAI
for Hearing.“ Lapyppgppppp. 58 (1948). p. 761.

8

9
by means of Speech Reception Threshold Tests. The second
measure is qualitative in nature in that it yields a picture
of a person’s ability to discriminate fine differences in
speech sounds when these sounds are given at a level easily
audible to the listener. This ability is evaluated by means
of phonetically balanced word lists. Since both tests
are similar to common auditory experiences, they add
validity to pure-tone audiometry as well as being valuable
for diagnostic and prognostic purposes.l Of these two
measures discrimination testing has been particularly
useful with individuals having difficulty in communication
because they confuse speech sounds even though they are able
to hear the speaker.

Davis, in his attempt to fill a need for a quantitative
measure of the social adequacy of hearing,:used these two
kinds of speech-hearing tests to develop the Social
Adequacy Index, a single number that indicates how well a
person hears speech under everyday conditions. The Social
Adequacy Index is derived from the relation of a patient's

discrimination score to the level at which he hears speech.2

V—r Y wv—V _,~_

1Hirsh, ppy_g;;., p. 321.

2Davis, M” pp. 776-777.

10

With this index it is possible to estimate numerically the
handicap of a person's hearing loss. The value of this index
in facilitating the planning of rehabilitation programs for
patients and in evaluating the results of fenestration
operations and hearing aids has placed an even greater
importance upon speech—hearing testing, and in particular.
discrimination testing.

A great deal of research and experimentation with a
variety of speech-hearing tests preceded the development
of speech—hearing tests as we know them today. Early
research in connection with the telephone, phonograph and
radio industries yielded information which aided the
development of these tests. From this research it was
learned that because words, parts of words, and individual
vowels and consonants vary greatly in their acoustic
characteristics, some words are more easily heard and under-
stood than others. Vowel sounds are heard twice as easily
as consonant sounds; thus, most mistakes in interpretation
can be attributed to the mishearing of consonant sounds.
Familiarity, mental acuity, word memory, and word associa-
tion were all found to be factors important to good hearing.

On the other hand, noises, interruptions, distractions, and

ll

cross-talk were found to interfere with good hearing.1

This information proved to be valuable in the
construction of test materials as did such criteria as
familiarity, phonetic dissimilarity, normal sampling of
English speech sounds, and homogeneity in terms of basic
audibility.2 More specific criteria have been adopted for
materials designed to test speech discrimination. These
criteria, as specified by Egan, are: (l) monosyllabic
structure. (2) equal average difficulty, (3) equal range
of difficulty, (4) equal phonetic composition, (5) composi-
tion representative of the English language, and (6) words
in common usage.3

One of the first speech-hearing tests developed was
that used by the Bell Telephone Laboratories in a study of
the efficiency of telephone circuits. This test, designated
as the ”Standard Articulation Lists," consisted of a large

series of unintelligible sounds-~combinations of consonant-

vowel-consonant, consonant—vowel, and vowel-consonant.4 An

j—v— v

HMacParlan, gpy_gi§y, p. 77.

2Hudgins, pp. 31., “Development of Recorded-Auditory
Tests for Measuring Hearing Loss for Speech," papypgpppppg,
57 (1947). p. 58.

3Egan, w, p. 958.
IMacParlan, 9p. cit., p. 77.

12

attempt was made to make these lists as much like speech as
possible but difficulty remained in the reporting of meaning-
less sounds heard and in the recording or writing of what
was reported.1

A more widely used speech-hearing test developed by
the Bell Telephone Laboratories used digits spoken in groups
of three for its items. It was one of the first recorded
tests and was used with the western Electric 4A.Audiometer.
The intensity of the recorded speech decreased in steps of
3 decibels. Although this was a much used test, it was
found to be ineffective in differentiating between uniform
and high-frequency hearing losses.2

One of the earlier tests of speech discrimination
developed was the wengel Audioselective Hearing Test. The
test, consisting of three groups of words, was designed to
measure the perception of and discrimination between voiced
and voiceless consonants, vowel resonances, and highnfrequency
consonants.3

In 1938 Robert West developed a speech-hearing test

helpful in discovering the frequency area of a hearing loss.

 

wa

11231” p. 79.
2Hudgins, pp, git., p. 60.
3MacFarlan. gpy_pipy, p. 90.

13

The test, one of so-called selective amplification, measures
hearing acuity for groups of words listed in various frequen-
cy zones.1

In 1940 L. A. Watson and Vern Knudsen constructed a
test designed to measure both the level of speech-hearing
acuity and speech discrimination. The test, composed of 69
words--20 vowels and 49 consonants, is first given to
determine threshold. Tests are then conducted at various
levels above threshold to find a percentage score of syllable
articulation.2

Another test of speech discrimination was developed
in 1941 by Alfred R. Thea. This "Word Hearing Test” is
comprised of blocks of three words which sound alike. After
listening to each group of words, the person being tested
indicates the word he believes he heard.3

In the 1940's the Psycho-Acoustic Laboratory (PAL) at
Harvard University conducted a program of audiometric test
development with three main objectives in mind. The first

of these was to explore further some of the problems associat-

ed with the construction of audiometric tests for the direct

 

v— __I_

lms” pp. 90-91.

2;p;g.. pp. 93-95.

3Ibid., p. 99.

l4

measurement of hearing loss for speech. .Much of the
earlier work with speech-hearing tests carried out by the
Bell Telephone Laboratories helped in accomplishing this
objective. The second purpose of the study was to produce
a test appropriate for exact laboratory measurements of all
degrees of hearing loss. Two tests, Auditory Test NO. 9.
Threshold of Hearing for Words, and Auditory Test NO. 12.
Threshold of Hearing for Sentences. were constructed to
meet this objective. These allowed for a rapid and dependable
measurement of the threshold of intelligibility and its
related clinical measurement, hearing loss for speech. A
high frequency test was developed to meet a third objective.
that of finding a means of differentiating between uniform
and high-frequency hearing losses. Hewever, this test was
found to offer no real advantage over pure-tone adiometry as
a diagnostic approach, so work was then concentrated on the
development of speech-hearing tests. leaving the differentia-
tion of various kinds of hearing loss to pure-tone audiometry.1

During the course of this articulation testing
program the Psycho-Acoustic Laboratory also constructed

several sets of word lists. From these lists of monosyllabic

 

1311dgin8. 92. gigs ( pp. 62.64 s

15

words, 24 lists of 50 words each were constructed. Words
were selected on the basis of the phonetic composition of
the first part of the word. These were called the RM (revised
monosyllabic) lists. Though somewhat satisfactory. Egan
felt the need for more phonetically balanced lists and thus
constructed the PB word lists. The P3 series consists of
20 lists each made up of so monosyllables.1

With a growth in general acceptance and use of speech
audiometry came the need for newer tests satisfying more
clinical needs. As a result, the Central Institute for the
Deaf refined the PAL tests in an attempt to correct some of
the deficiencies that had been noted in them. For example..
it was discovered that some of the recordings of the
Auditory Test No. 9 yielded different thresholds than others.
The vocabularly on the P3 lists was found to be too long and
unfamiliar, and the recordings were not in standardized
form. The revisions made by the Central Institute for the
Deaf are in the form of three tests, presently widely

accepted for speech-hearing testing.2

CID Auditory Tepg W-;.—-This test. measuring the

 

lEgan' OE. GEE. 1 pp. 962-963.

2Hirsh, 9p, git,, p. 322.

16

threshold of intelligibility for speech, is made up of 36
spondaic words (two-syllable words in which both syllables
are equally stressed) chosen on the basis of ratings of
familiarity from the 84 spondaic words on the PAL Auditory
Test No. 9. The words are recorded at a constant level
10 decibels below the carrier phrase, "Say the word.“ Six
scramblings of the original list are available.1

CTD Auditory Test W- .--The same words and six word
orders comprising the CID Auditory Test W—l are used in this
test. The intensity of the words is attenuated within each
list at the rate of 3 decibels for every three words, thus
allowing for a rapid estimate of the threshold of intelligi-
bility for speech.2

CID Auditpry Tegp W—2 .--This test, a modification of
the PAL PB-SO Lists, is designed to determine a patient's
discrimination loss for speech. This loss is designated as
the difference between 100 per cent and the per cent of the
words presented that a listener repeats correctly at a level
that is sufficiently high so that further increase in inten-

sity is not accompanied by further increase in the number of

 

"—V

1;bid.. p. 323.

2;bid., p. 326.

17
words repeated correctly. Two hundred monosyllabic, phoneti-
cally balanced words make up four lists of words, each of
which has six rscraniblings. Each word is preceded by the
carrier phrase, "You will say." The words were selected to
meet a criteria of familiarity and phonetic composition

similar to that of the English language.1

The Use of Binaural Hearing Aids

The recent development of binaural hearing aids has
stimulated a new interest in binaural hearing and the possi-
ble benefits of binaural amplification for hard of hearing
individuals. Research in the area of binaural hearing,
however, is not new. Much information exists concerning
the.advantages of two-eared hearing. Listed among these
advantages are better localization, discriminative selection,
speech sound discrimination, more ease of listening, better
sound identification, and improved sound fidelity.2

From such research it might well be assumed that

similar benefits can be derived from binaural hearing aids.

However. much of the information gathered thus far on the

f

11bid.. pp. 328-329.

2LeRoy D. Hedgecock, and Boyd V. Sheets, "A Comparison
of Monaural and Binaural Hearing Aids for Listening to Speech."

AgM.A. Archives of Otolaryngology, 68 (1958). P. 624.

18
properties of binaural hearing has been obtained from
normal hearing subjects. There is considerable empirical
evidence indicating that hard of hearing individuals often
do not respond to sound amplification in the same manner as
normal ears. Also, not all hard of hearing persons benefit
from a hearing aid even of the monaural type.1 Considerations
such as these and the fact that clinicians must be aware of
the advantages and limitations of binaural systems in order
to have well defined criteria for the hard of hearing patient
have pointed to a need for careful study of binaural hearing
aids.

It is the belief of Haskins and Hardy that the benefits
of a binaural hearing aid cannot always be assessed by formal
clinical testing. They have found that often this can be
determined only by the patient's own listening experience
under conditions in which he needs amplification.2

Similarly, Kodman discovered certain advantages which
he felt could not be determined by clincial techniques. From
a sample of 50 successful binaural eyeglass hearing aid users

he found that 42 per cent had no criticisms of their aids as

 

vfi

1%” p. 625.

2Harriet Haskins and William G. Hardy, "Clinical Studies
in Stereophonic Hearing,“ Laryngoscope, 70 (1960), p. 1433.

19

compared with 30 per cent reported by monaural hearing aid
users in a previous study. As a result of his study he
suggests that binaural hearing promotes an intra-aural
effect that manifests itself in better sound balance and
ease.of perception. The latter may not be shown in the
discrimination score.1

Carhart, on the other hand, advocates more rigid clini-
cal procedures for the study of binaural hearing aids. He
streses a need for refining and standardizing methods for
appropriately testing the efficiency of binaural aids. In
order to approximate the difficult listening situations of
everyday life he suggests that these methods must embody a
certain rigor and acoustic complexity. Three such procedures
are discussed: (1) Measurement of discrimination for phoneti-
cally balanced words when these are presented in noise,
(2) Measurement of an individual's ability to attend to one
of two competing trains of test items, and (3) Measurement
of the ability to discriminate test material that competes

with itself, as occurs in everyday situations when reverbera-

tion and reflection of sound are severe.2

 

1Prank Kodman, "Successful Binaural Hearing Aid Users,"

ggcpivgp pf Qtolapypgology,74, (1961). pp. 302-304.

2Raymond Carhart, “The Usefulness of the Binaural Hear—

ing Aid." Tganppptipns of the American Academy pf Ophphgmglogy
ppg Opolapyngolpgy, 62 (1958). pp. 125-126.

20

During the past six years a number of procedures
similar to these, as well as other techniques, have been
devised and tested to compare binaural and monaural hearing
aids with respect to their ability to improve hearing for
speech. The results of some of these studies shall be
considered at this time.

One of the earlier studies of this nature was
conducted by Markle and Aber at the Hearing and Speech
Center of the New York University-Bellevue Medical Center.
Ten subjects with clincial otosclerosis, considered to be
ideal hearing aid candidates, were tested, first while
wearing a "conventional" hearing aid in a "conventional“
manner, and then with two "conventional" hearing aids.
one mounted on each side of the head. Auditory Tests
W-l and W-22 were administered at signal/noise ratios of
+10, 0, and ~10. No significant difference in speech
reception thresholds was found between the two
listening conditions. At signal/noise levels of +10 decibels
there was a slight difference in discrimination with the
binaural hearing aid being favored. Significant differences

in discrimination were found at the signal/noise levels of 0

21

and ~10.1

Hedgecock and Sheets in testing 30 hearing impaired
subjects with monaural and binaural amplification at the
Mayo Clinic obtained differential results which were not
Statistically significant, but which revealed a trend
favoring the binaural over the monaural hearing aid fitting
in respect to speech discrimination. Unlike the Markle
and Aber study, testing was conducted in quiet surroundings.
In addition, they found that when relative severity of
hearing was considered, subjects falling into the category
of moderate hearing losses, for the most part, derived
greater benefit from the binaural aid than those with milder
or severer hearing losses.2

In a later study by Belzile and Markle the efficiency
of monaural and binaural hearing aids was again compared in
a noisy environment. In this investigation only individuals
with conductive or perceptual hearing losses were studied.
Those with bilateral conductive losses achieved higher

discrimination scores with the binaural aid than With the

 

1 - ..
Donald M. Markle and William C. Aber, "A Clinical
Evaluation of Monaural and Binaural Hearing Aids," Archives

9; Otolgryngology, 67 (1958). PP. 606-608.
2Hedgecock, op: cit,: pp. 624-629.

22

monaural in all listening conditions tested (+20 through ~10
signal/noise levels). Subjects with bilateral perceptual
losses received higher scores with the binaural aid only in
the listening conditions representing signal/noise ratios
between +10 and 0. For both groups the improvement was most
significant at the 0 signal/noise ratio; however, it waS'
discovered that for both groups 50 per cent discrimination
can be achieved in the presence of 10 decibels more noise
while wearing a binaural hearing aid than while wearing a
monaural aid.1

Jerger and Dirks later replicated this study with the
exception that for the monaural listening condition they
mounted the hearing aid on the subject's head rather than on
the body as did the previous investigators. Jerger and
Dirks' results failed to confirm the binaural superiority
found in the Belzile and Markle study.2 Hirsh believes that
this discrepancy in results might well be due to the slight

difference in procedure, since in the Jerger study the single

\
r Y

lMarcel Belzile and Donald M. Markle, "A Clinical
Comparison of Monaural and Binaural Hearing Aids WOrn by
Patients with Conductive or Perceptual Deafness," Larynggr
5.2222. 69 (1959). pp. 1317-1323.

2James Jerger and Donald Dirks, “Binaural Hearing

Aids. An Enigma," Journal of the Acggstical Society of
Amerigg, 33 (1961), p. 537.

23

aid derived benefits from head movement in the monaural
condition.1 Nevertheless, it is felt by the investigators
that head mounting of the single aid provides a more exact
procedure for comparing monaural and binaural hearing aids
with respect to discrimination in noise.2

To explore the comparative values of binaural,
pseudo-binaural, and monaural listening, DiCarlo used 60
subjects with conductive, mixed, or sensory-neural losses
as an experimental group and 20 normal hearing adults as
a control group. The three types of amplification were used
to determine speech reception thresholds, discrimination
scores, speech-noise ratios, and localization. The results
of this study showed that binaural listening provided some
lowering of the speech reception threshold as compared with
the pseudo-binaural and better monaural thresholds; however,
discrimination scores were not significant for any of the
listening conditions. Amplification by means of the
binaural hearing aid proved to be better for localizing

a noise source than either the pseudo-binaural or the monaural

 

gbid.
21:211.. p. 358.

l

24

aid. In general monaural listening was subjectively
preferred to binaural listening for the required tasks by the
hearing impaired subjects.1

Two types of measurement using competing speech sig-
nals were used by Jerger, Carhart, and Dirks in one of the
most recent studies to determine the possible advantages
of binaural hearing aid use for increasing speech intelligi-
bility. Their 48 subjects, all having sensori-neural hearing
losses, were tested with monaural-body, monaural-head, and
binaural-head hearing aids. The binaural listening condition
was not found to be markedly superior, although on the
NOrthwestern University (NU) Test #2 there was a slight
(roughly 10 per cent) improvement in PB discrimination
against a background of competing sentences. NU Test
#3 yielded results showing no improvement in sentence
intelligibility with a background of continuous discourse

with the binaural hearing aid.2

 

liouis DiCarlo and William J. Brown. "Effectiveness of
Binaural Hearing Aids for Adults with Hearing Impairments,"

2 .

James Jerger, Raymond Carhart, and Donald Dirks,
"Binaural Hearing Aids and Speech Intelligibility."

Qgggng; g; Speech and Hgaging Reggargh, 4 (1961). pp. 137-

148.

CHAPTER III

SUBJECTS, EQUIPMENT, MATERIALS, AND

TESTING PROCEDURES

In order to carry out this study a procedure was
decided upon that called for testing of university students.
A minimal amount of materials and equipment was required.
Subjects employed, as well as the materials, equipment.

and testing procedures used are described below.

Subjects

Twelve university students, eleven females and one
male, were the subjects for this study. It was determined
audiometrically that each subject had normal hearing. They
all were administered a pure tone sweep check test at 15
decibels at frequencies 250 through 6000 cycles per second.
They ranged in age from 20 to 26 years and in education, from
three to five years of college. Although no effort was made
to select subjects on the basis of a particular educational
beekground, Six subjects were majors in speechand hearing
science.

25

26

Eggigment

Pure-tone portable audiometer (Beltane, Model lO-A,
see Appendix A, page 44)

Two tape recorders (wellensack, Model T1500)

Clinical audiometer (Allison, Model 21)

Binaural hearing aid (Beltone eyeglasses-“Bolero»3ed Dot")
Batteries (RM 675)

Individual plastic ear inserts of general sizes

Sound pressure level meter (M.S.A. Soundscope)

Materials

c115 Auditory test w-22 (Lists 1A, 2A, 3A, 4A, 13,
23, 33, and 43, see Appendix
3, page .45)
' Tape recorded white noise
Forms for the recording of responses to each list

by the subjects. (See
Appendix C, page.49)

Procedure
Preliminary procedures.--The CID Auditory Test W-22
recordings were transcribed onto magnetic tape at the studios
of the Michigan State University radio station WKAR. Two
tapes, one of lists 1A, 2A, 3A, and 4A and the other of lists
13, 23, 33, and 43 were made. In order that the speech

stimulus could be presented at the same level to all subjects,

27
a 1000 cycle per second calibration tone was recorded at the
beginning of each tape. A third tape of white noise was ‘
made to be presented simultaneously with the CID lists in
order to provide a constant ambient noise level in the room
used for the first part of the testing. Forms for the
recording of responses to each list by the subjects were
devised by the examiner.

Each subject was given a pure—tone sweep check hearing
test monaurally in each ear at 250, 500, 1000, 2000, 4000, and
6000 cycles per second at a level of 15 decibels. This
screening took place in the children's hearing testing room
of the Michigan State University Speech and Hearing Clinic.
No subject was included in this study who failed the
screening test at any one of the frequencies.

T st n -—Ph 8 n .--In order to determine whether
subjects' discrimination differed as they were provided
amplification by a binaural hearing aid, CID Auditory Test
W-22 discrimination testing was conducted. This testing was
carried out in a room the dimensions of which are 73.5' x 61'
x 9'. The walls and ceiling are plastered; the floor is
cement. The room appeared to be somewhat reverberant. The
background noise of the room without additional white noise

was tested by the sound pressure level meter using the C scale

28
and was found to be 48 decibels.

The calibration tone of the tapes of the CID lists as
each was presented was set at 70 decibels, 18 decibels above
the level of the white noise which was set at 52 decibels.
These measurements were taken from position one, a distance
of 24' from the source of the sound. The two tape recorders
were centrally located along the front wall of the room. As
each subject was tested, he was seated in direct line with
the tape recorders at distances of 24', 48', and 72'. The
third position was located at the back wall of the room. The
CID lists were presented to each of the subjects, aided and
unaided, at each of the three positions. Thus, six different
listening conditions were involved for which six different
phonetically balanced lists of words were used for each
subject. Responses were recorded by the subjects for each
list as the words were presented. The order of the conditions
was randomized for all persons according to EdwardS' Table
of Random Numbers in an attempt to lessen the possibility
of practice effects.1 The subjects were tested individually

except for once instance when two were tested together. Prior

 

1Allen L. Edwards, Statistical Methods for the Behavior-
a1 Sciences, (New York: Holt, Rinehart and Winston, 1961),
pp. 250-251.

29

to the testing with the hearing aid each subject was carefully
fitted with individual ear inserts of general sizes ranging
from small to large. Because the hearing of the subjects
was normal, the volume control of the hearing aid was
arbitrarily set by the investigator, while wearing the aid.
at a level just below that at which feedback was present.
This setting was held constant for each subject.

Testing-Phase th.-—In order to have a standard of
comparison for the tests made in the reverberant room, the
effects of amplification upon discrimination in a relatively
noise-free environment were measured by testing the subjects
in the sound—treated testing rooms of the Michigan State
University Speech and Hearing Clinic. For this testing a
speech audiometer and the standardized CID Auditory Test
W~22 recordings were employed. These were presented free-
field to each subject, aided and unaided, in randomized order.
The subjects, tested individually, were seated at a distance
of 10 feet from the speaker. In order to make the listening
task sufficiently difficult the words were transmitted
at a level of 0 decibels. White noise was not used in this
testing. As in Phase one, the subjectskwrote down their
response. to the CID Auditory Test W-22 test lists on forms

provided them.

CHAPTER IV
RESULTS AND DISCUSSION

Results
The test results were tabulated and subjected to
statistical treatment. Since it was the desire of the
investigator to predict the significance of the difference
between the mean scores of the six listening conditions, a
.; test was carried out (the quantity g is the distance
from the means expressed in terms of standard error of

the mean).1 The formula £a=il + i} was used.2 There were

 

31--

3
is

12 subjects in the study; thus the degrees of freedom were
(N-l) or 11. With 11 degrees of freedom a ;_of 2.201 is
needed for significance at the .05 level of confidence.

A,§ of 3.106 is needed for significance at the .01 level of
confidence. The results of the tests for g are presented in

Table I and Table II.

V w

1
Henry 3. Garrett, Statistics in Psychology and Education,

(New'York: Longmans, Green, and Company, 1947), p. 191.

V'—

2Edwards, 92,21t,, pp. 253-254.
30

31
TABLE I

3;, scones son pmsr 1 or resume

(museum noon)
m

 

Listening Mean Per cent 3” Level of
Condition Scores .5 Confidence

l - U 32.66 4.98 Significant

l - A 6.83 at l per cent
2 - U 27.50 5.77 Significant

2 - A 6.83‘ at 1 per cent
3 - U 33.33 4.98 Significant

3 - A 12.50 at l per cent
1 - A 6.83 0 Nonsignificant
2 ~ A 6.83 at 5 per cent
1 p A 6.83 ‘ -2.00 Nonsignfficant
3 - A 12.50 at 5 per cent
3 - A 12.50 at 5 per cent
1 - U 32.66 - .77 ansignificant
2 - U 27.50 at 5 per cent
1 — U 32.66 — .10 Nonsignificant
3 — U . 33.33 at 5 per cent

)

2 - U 27.50 -l.08 ansignificant
3 - U 33.33 " at 5 per cent

" V. v7 ‘w w—vv v v w— r T,

Position 1 (24')
Position 2 (48')
Position 3 (72')
Unaided

Aided

>‘Cidtor4
l

32
TABLE 11
;_scoss son 93383 2 or TESTING

(sousn—rnsnrss soon)
m

 

Listening Mean Per cent Level of
Condition Scores ;_ Confidence
Unaided 56.33 1.71 Nonsignificant

Aided 45.17

—— , ~—— .Tv—f firs. v—w ‘7— —._..w—.—.—

at 5 per cent

W ——. w— , “

Eisssssiss

The 3 scores for positions 1. 2, and 3 are significant
at the l per cent level of confidence, indicating that
amplification does make a difference in speech discrumination
of normal hearing subjects when tested in a background of
noise. In each case discrimination was better in the
unaided listening condition.

In answering the question of whether discrimination
of speech varies as a function of distance from the source
of the sound. it was necessary to consider mean scores of
both the aided and unaided listening conditions. These are
presented in Figure 1. There was no difference between the
aided scores at positions 1 and 2. A slight difference exists
between the aided scores of positions 1 and 3, however. this
difference is not statistically significant at the 5 per

cent level of confidence. A difference. significant at the

Percent'correct'

Figure 1.

100
95
90
85
80
75
7O
65
60
55
50
45
4O
35
30
25
20
15
10

 

M

32.66

34

P r t Sc e f Ph

 

 

Position 1

24'

27.50

 

 

 

 

Position 2
48'

Listening Conditions

Te t

 

Unaided

)_
Aided m

E \

33.32

 

 

 

 

Position 3
72'

35
5 per cent level of confidence, was found between the aided
scores of positions 2 and 3. In both instances scores were
highest in the third position, the greatest distance from
the source of the sound.

The 5 scores for the unaided listening conditions
indicate a tendency similar to that shown by the ; scores
for the aided conditions. Unlike the aided conditions,
however, a slight, though statistically nonsignificant,
difference was found between the mean scores of positions
1 and 2 in the direction of the position closest to the
source of the sound. Differences also existed between
positions 1 and 3 and between positions 2 and 3, but neither
was significant at the 5 per cent level of confidence. In
both cases discrimination was better at the distance
farthest from the source of the sound.

Judging from these results, in which in every
instance but one there was a difference between positions,
one might conclude that distance is a factor in the
ability to discriminate speech. It is to be noted that
all but one of these differences (although statistically
significant in only one case) were better at the greater
distance from the source of the sound, a somewhat surprising

result. It appears very likely that the reverberant nature

36
of the listening environment in which this expermment
took place was a real factor, however, the possibility of
another variable should also be considered. Although the
six listening condidtions were randomized for each subject,
it is to be noted that a greater number of them were tested
last in the third position than in the first or second
positions. Thus, in spite of an attempt to minimize practice
effects, it is possible thatitheyndideoccur and were
manifested in higher discrimination scores at the greatest
distance from the source of the sound.

In the sound-treated room there was a small difference
between the aided and unaided listening conditions, better
discrimination being found in the unaided condition. This
is shown in Figure 2. This difference was not significant
at the 5 per cent level of confidence. Thus, it appears
that, although the subjects performed better on
discrimination tasks without the amplification of the binaural
hearing aid, the difference between the aided and unaided
conditions was not as great in the sound-treated room as it
was in the room used for Phase 1 of the testing.

In the latter room discrimination scores in both
aided and unaided listening conditions were generally

lower than those obtained in the sound-treated room. This

Figure 2.

Percent correct

37

Mean Percent Scores for Phase 2 of Testing

100
95

90
85
80
75
7O
65
60

55
50

 

Unaided I 5]

Aided m

 

56.33

 

 

 

 

45.17

 

Listening Conditions

38
might well be accounted for by the reverberance of the room.
The fact that discrimination was more adversely affected in
the aided listening condition, however, leads the investi-
gator to suspect that the lower scores might well have been
a function of the increased distortion produced by the

hearing aid in Phase 1 of the testing.

CHAPTER V

SUMMARyiAND CONCLUSIONS

Summary

The problem of achieving greater social adequacy of
hearing for the hard of hearing person by means of amplifi-
cation with a hearing aid has been studied for many years.

It has been recognized that one of the greatest difficulties
in dealing with this problem is that expected improvements
in the ability to discriminate speech as a result of ampli-
fication with hearing aids are not always found due to two
distorting factors. These\are the hearing loss itself, and
the manner in which sound is reproduced with the hearing aid.
Therefore, the question of what effects amplification have
on speech discrimination of normal hearing people has been
raised. A review of thelliterature reveals a paucity of
information pertaining to this questions. Thus, the

purpose of this study has been to determine if amplification
with a binaural hearing aid improves or hinders the speech
discrimination ability of normal hearing people.

Twelve university students participated as subjects for

39

40
the study. A pure—tone screening test at 15 decibels elim-
inated as subjects all whose hearing was not within the
defined normal limits. For Phase 1 of the testing procedure
the standardized recordings of the CID Auditory Test W-22
(Lists 1A, 2A, 3A, 4A, 13, 23, 33, and 43) were transcribed
onto magnetic tape and played to the subjects at a level of
70 decibels. In order to control the ambient noise level
of the room white noise at a level of 52 decibels was
employed. The subjects were tested individually (in all
cases but one when two were tested together) in a reverber-
ant room at distances of 24, 48, and 72 feet from the
source of the sound. At each distance the subjects
responded to words with and without amplification and‘
recorded their responses on forms provided them.

In Phase 2 of the testing the CID Auditory Test W-22
was again administered individually to the subjects, aided
and unaided, in a sound-treated room to determine the
effects of amplification in a relatively noise-free
environment. The words were presented free-field without
white noise at a level of 0 decibels.

The results of the study show that in comparing the
aided and unaided listening conditions in all positions of

Phase 1 of the testing, subjects obtained higher scores

41
without amplification, the differences being statistically
significant at the l per cent level of confidence. In Phase
2 of the testing the subjects also performed better in the
unaided listening condition, however, the difference was
not statistically significant.

In comparing aided with aided scores and unaided
with unaided scores for all three positions, differences
were found which, in all but two instances showed better
discrimination for positions that were farthest from the
source of the sound. There was no difference between the

. mean per cent scores for the aided listening conditions at
positions 1 and 2. A comparison of the unaided scores
at these positions showed better discrimination at the

position closest to the source of the sound.

anclusions

Within the limits of this study the following
conclusions are offered:

1. There is a lowering of speech discrimination
scores as a result of applying a hearing aid to the ears of
normal hearing subjects in a reverberant room with a
background of white noise.

2. Speech discrimination does not decrease as a func-

tion of distance from the sound source.

42

3. There is no definite trend in speech discrimina-
tion through the conditions aided and unaided.

4.. Speech discrimination becomes more difficult as
a result of amplification in a relatively noise-free
environment.

5. Lower speech discrimination scores are obtained
with amplification by a binaural hearing aid as compared to
those obtained without amplification in a relatively noise-
free environment.

6. Whether the subject is wearing a hearing aid
or not, speech discrimination is generally more difficult in
a reverberant room with a background of white noise than

in a sound—treated room without white noise.

Im c f Putu Res rch

This study has shown several tendencies relating
to the effects of amplification on the speech discrimination
performance of normal hearing subjects when tested under
certain conditions with the CID Auditory Test W-22. It is
known that various other environmental conditions affect the
hearing of normal hearing people without amplification. How-
ever, further research will be needed in order to determine
the effects of such conditions when amplification is applied

to the normal ear. Information relative to this problem

43
might well be gained from a study similar to the one reported
here but carried out in an open field and at greater varying
distances from the sound source. It might also incorporate
the use of individual ear inserts made for each subject and
amplification applied at the Most Comfortable Loudness level
for each subject. With information gained from such a study
it is felt that more answers might be obtained to the
question of how speech discrimination of normal hearing
subjects is affected by amplification and, ultimately, how
the needs of hard of hearing individuals might best be met

as regards amplification and discrimination.

44

APPENDIX A

Acoustical Characteristics of

the Binaural Hearing Aid1

'3; 130
;.Q
unit 120
.333
5 ac: 110
ONO
mo.
53 100
so.»
a u
figs W
3"!)
U)

80

 

Maximum Acoustical
Gain db

 

1 2 3 4 5 7 1 2 3 4 5 7 1
100 H 1000 10.000'

Frequency - CPS

lgglrgng Consrltgnt's Manrgl, 1961, Section IV,
I-5, Page 4. "Bolero Red Dot."

C O

\OQNIO‘UlfiwNH

1...-
O

11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.

C.I_[_.Da AUDITORY TEST W-22 (PB WORD LISTS)

M

an 26.
yard 27.
carve 28.
us 29.
day 30.
toe 31.
felt 32.
stove 33.
hunt 34.
ran 35.
knees 36.
not (knot) 37.
mew 38.
low 39.
owl 40.
it 41.
she 42.
high 43.
there (their)44.
earn (urn) 45.
twins 46.
could 47.
what 48.
bathe 49.
50.

ace

APPENDIX B

45

you (ewe) 1.
as 2.
wet 3.
chew 4.
see (sea) 5.
deaf 6.
them 7.
give 8.
true 9.
isle (aisle)10.
or (oar) 11.
law 12.
me 13.
none (nun) 14.
jam 15.
poor 16.
him 17.
skin 18.
east 19.
thing 20.
dad 21.
up 22.
bells 23.
wire 24.
ache 25.

List 2A
yore (your) 26.
bin (been) 27.
way (weigh) 28.
chest 29.
then 30.
ease 31.
smart 32.
gave 33.
pew 34.
ice 35.
odd 36.
knee 37.
move 38.
new 39.
jaw 40.
one (won) 41.
hit 42.
send 43.
else 44.
tare (tear) 45-
does 46.
too (two, to)47.
cap 48.
with 49.
air (heir) 50.

and
young
cars
tree
dumb
that

die (dye)
show
hurt

own

key

oak

new (knew)
live (verb)
off

ill
rooms
ham

star

eat

thin
flat
will

by (buy)
ail (ale)

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
239
24.
25.

APPENDIX B

46

(Continued)

c,I.D. AUDITOR; TEST w-2z. ' (P3 WORD LISTS)

Lrsr 3A

bill

add (ad)
west
cute
start
ears

tan

nest

say

is

out

lie (lye)
three
oil

king

pie

he
smooth
farm
this
done (dun)
use (yews)
camp
wool

are

gates
26. aim 1. all (awl) 26.
27. when 2. wood (would) 27.
28. book 3. at 28.
29. tie 4. where 29.
30. do 5. chin 30.
31. hand 6. they 31.
32. end 7. dolls 32.
33. shove 8. so (sew) 33.
34. have 9. nuts 34.
35. owes 10. ought (aught)35.
36. jar 11. in (inn) 36.
37. no (know) 12. net 37.
38. may 13. my 38.
39. knit 14. leave 39.
40. on 15. of 40.
41. if 16. hang 41.
42. raw 17. save 42.
43. glove 18. ear 43.
44. ten 19. tea (tee) 44.
45. dull 20. cook 45.
46. though 21. tin 46.
47. chair 22. bread (bred) 47.
48. we 23. why 48.
49. ate (eight) 24; arm 49.
50. year 25. yet 50.

darn
art

will
dust
toy

aid

than
eyes
shoe
his

our (hour)

men

near

few

Jump

pale (pail)

go

stiff

can

through (thru)
clothes

who

bee (be)

yes

am

(ayes)

m‘wNH
eeeee

(Duo

9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.

47

3 (Continued)

APPENDIX
C D. AUDITORY ST W42
Lrgr ;B
carve 26. dad
wire 27. stove
felt 28. ache
thing 29. us
knees 30. him
poor 31. not (knot)
owl 32. me
law 33. it
there (their)34. see (sea)
give 35. earn (urn)
what 36. true
chew 37. bathe
as 38. you (ewe)
twins 39. wet
isle (aisle) 40. could
ace 41. them
deaf 42. high
she 43. or (oar)
none (nun) 44. low
new 45. jam
skin 46. ran
hunt 47. east
up 48. toe
day 49. bells
an 50. yard

P3 WORD LI TS)

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.

Li t

way (weigh)
'by (buy)
smart

eat

odd

ill

jaw

oak

else

show

can

tree

young

air (heir)
that

does

own

hit

live (verb)
more

ham

pew

die (dye)
then

yore (your)

8

26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.

ail (ale)
chest
thin
gave
rooms
knee
send

one (won)
hurt
tare
dumb
with
and
cars
too (two.
flat
neW'(knew)
key

now

off

ice

star

ease

well

bin (been)

(tear)

to)

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.

APPENDIX B

48

(Continued)

Q.I.D. AUDITORY TEST W-22 (PB WORD LISTS)

L

year
cute
though
hand

raw

lie (lye)
may

pie

have
this

do

wool

aim

book

use (yews)
end
smooth
jar

oil

is

start

on

ears

we

add (ad)

38

26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.

west

ate (eight)

tan
dull
out
if
king
no (know)
farm
shove
camp
tie
When
are
ten
done (dun)
owes
he
knit
nest
glove
say
chair
bill
three;

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.

Lrgt 43
chin 26.
all (awl) 27.
who 28.
few 29.
stiff 30.
my 31.
nuts 32.
save 33.
his 34,
tin 35.
aid 36.
yet 37.
art 38.
so (sew) 39.
why 40.
darn 41.
tea (tee) 42.
men 43.
of 44.
pale (pail) 45.
our (hour) 46.
through(thru)47.
dolls 48.
yes 49.
at 50.

wood (would)
bee (be)
they

dust

ought (aught)
Jump

leave

in (inn)

ear

than

bread (bred)
will

eyes (ayes)
arm

toy

cook

shoe

hang

near

go

can

net

clothes
where

am

10.

11.

12.

49

APPENDIX C

-ANSWER SHEET

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Subj. No. Condition No. List No. ___
21. 41.
f 22. fir 42.
23. _ 43.
24. 44. -
25. 45. i
26. 46.
27. 47.
28. - 48.
29. 49.

 

 

 

30. 50.

 

 

31.

 

 

32. - A

 

13.

14.

33. , ,

 

34.

 

 

15.

35.

 

 

16.

17.

18.

19.

20.

36.

 

 

37.

 

 

38.

 

 

39.

 

 

40.

 

 

50

APPENDIX D

RAW SCORES PER CENT CORRECT FOR PHASE 1.0? TESTING
(REVERBERANT ROOM)

 

 

 

 

 

WSufifbjwe‘cPt # -. f Position -
l 2 3
- Aided Unaided Aided. Unaided Aided Unaided
1 6 10 10 24 12 36
2 4 4O 8 34 10 4O
3 2 18 4 6 16 18
4 10 24 10 26 8 36
5 10 50 2 24 22 26
6 8 28 6 30 8 36
7 16 6O 6 46 8 50
8 O 28 10 30 14 30
9 8 38 6 36 10 54
10 2 28 4 20 14 14
11 10 34 10 28 22 34

12 6 34 6 26 6 26

 

51

APPENDIX D (Continued)

RAW scones PER-.CENT OORRsc'rzroszpsAss 2 or resume
(SOUNDgTREATED ROOM)

 

 

 

 

m .1 L- .
Subject # Aided Unaided

WWW— Tl WV 48 5487
2 48 78

3 44 66

4 48 40

5 34 S 2

6 . 48 42

7 24 72

8 46 54

9 46 68

10 46 40

11 6O 7O

12 50 46

BIBLIOGRAPHY

Books

Edwards, Allen L. Srarrgtrcg; Mgthods for the Behavigra;

Sciggggs. New York: Holt, Rinehart and Winston,
1961.

Garrett, Henry 3.. S a stics 1 Ps ch 0 and E uca i n.
New York: Longmans, Green and Co.. 1947.

Kranz,_Pred W. Hearrnq Aids. Elmsford, NeW'York: Sonotone
Corporation. 1946.

Newby. Hayes A. Audiolgqy. New York: Appleton-Century-
Crofts, Inc., 1958.

Periodicals

Belzile. Marcel. and Markle, Donald M. "A Clinical Compari-
son of Monaural and Binaural Hearing Aids Worn by
Patients with Conductive or Perceptual Deafness,"

W. 69 (1959). 1317-1323.

Carhart, Raymond. "The Usefulness of the Binaural Hearing

Aid." Trrngacts of the Aggrrcan Agaggmy 9f Qphrhamglgqy
gag orglgryngglogy. 62 (1958). 120-126.

Corliss. Edith L. R. "Types of Distortion in Hearing Aids."
Abstracted in ASHA, 3 (1961), 344—345.

Davis, Hallowell. "The Articulation Area and the SAI for
Hearing." Laryngoscope, 58 (1948), 76ln778.

DiCarlo. Louis M., and Brown. William J. “Effectiveness of
Binaural Hearing Aids for Adults with Hearing Impair-

ments," _Journal or Auditory Resgargh, l (1960). 35-76.

Egan, James P. “Articulation Testing Methods," ngxagggsggg.
58 (1943). 955-991.

52

S3
Haskins, Harriet L., and Hardy, William G. "Clinical Studies

in Stereophonic Hearing," Laryngggcope..70£‘(1960).
1427-1433. .

Hedgecock, LeRoy D., and Sheets, Boyd V. "A Comparison of
Monaural and Binaural Hearing Aids for Listening to

Speech,” rchrves 9f Otolaryngolgqy, 68 (1958),
624-629.

Hirsh, Ira J., Davis, Hallowell, Silverman, S. Richard,
Reynolds. Elizabeth,G., Eldert,.Blisabeth, and Benson,
Robert W. "Development of Materials for Speech

Audiometry," Journal 9f Speech and Hearrng Dis-
orders. 17 (1952). 321—337.

Hudgins, Clarence, gr. g;. "The Development of Recorded
Auditory Tests for Measuring Hearing Loss for Speech,"

Lgrynqogcgp , 57 (1947), 57-89.

Jerger, James. "Binaural Hearing Aids. An Enigma," Journal

of the Acoustical Sociery 9f America, 33 (1961),

Jerger, James: Carhart, Raymond, and Dirks, Donald. "Binaural
Hearing Aids and Speech Intelligibility," Journal

9f Speech rad Hearing Rgsearch, 4 (1961), 137—148.

Kodman, Prank. "Successful Binaural Hearing Aid Users."

Arghives 9f Otolaryngglggy, 74.(1961), 302-304.

MacParlan, Douglas. "Speech Hearing Testing,“ Laryngo—
gggpg, 55 (1945). 71-115.

Markle, Donald M., and Aber, William. Gt; fiAcolinicaIqualuation
of Monaural and Binaural Hearing Aids," Archrvgg er

orolaryngology,68 (1958), 606-608.

Other Materials

ggltgge Consulrant's Manual, 1961, Section IV, I-S,

page 4.

 

 

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“——

   

 

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