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AN EMPIRICAL EVALUATICN 0F
SQCKM. ADEQUACY INDEX 903 HEARING

Thesis {or Hm Dogma of M‘ A.
MECBEGAN STATE UKWEBSITY

Bari Louise S-chorenkerman

1965

 

THESIS

LIBRARY

Michigan State
University

 

 

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ABSTRACT
AN EMPIRICAL EVALUATION OF
THE SOCIAL ADEQUACY'INDEX FOR HEARING
by Bari Louise Schoenkerman

In 19h8 Hallowell Davis devised a Social Adequacy Index
for Hearing (SAI). It provides a numerical value of a client's
difficulty in communication due to his hearing loss. The SAI is
determined in the following way: measurements of the client's
speech reception threshold and maximum discrimination ability
are obtained, and these scores are applied to a table of scores
developed by Davis.

There has been some doubt cast upon the validity of this
measurement due to the fact that the scale is based on Harvard
university Psycho-Acoustic Laboratory Phonetically Balanced word
lists, and most clinics now use Phonetically Balanced word lists
developed at the Central Institute for the Deaf. Also, Davis
computed his scale statistically from a group of normally'hearing
subjects listening to undistorted material. It is the intent of
the present study to ascertain whether or not differences in ma-
terial and differences in listening conditions provide signifi-
cant differences in scores which might hinder the validity of this
measurement,

Thenty-four university students were tested under different

BARI LOUISE SCHOENKERMAN

conditions at levels of 33 dB, 48 dB, and 63 dB, re. 1951
American Standards Association standards. The Social Adequacy
Index estimated empirically by Davis's method, by definition,
represents a mean of discrimination scores of tests administered
at the above mentioned levels.

There were four tapes used in this study. Distortion was
introduced by the use of an audiometer filter which attenuated
the intensities of the various signals at the rate of 30 dB per
octave above the cut-off points. These points were as follows:
2400 cps, 1200 cps, 600 cps, and no cut off. Fifty dB of white
noise was introduced in addition to the frequency distortion
when testing twelve of the subjects.

Each of the subjects was given the following battery of
tests: a speech reception threshold test, a maximum discrimi-
nation test, and discrimination tests at the following levels:
33 dB, 48 dB, and 63 dB, re. 1951 American Standards Associ-
ation standards. The experimental SAI was derived by averaging .
the discrimination scores of the latter three tests, and the
estimated SAI was derived by applying the speech reception
threshold score and the maximum.discrimination score to the
Davis SAI scale. These two scores were then statistically com-
pared. There was a high, positive correlation (.94) between the

two methods. A low t.ratio of .016 showed no statistical dif-

BARI LOUISE SCHOENKERMAN

ference between the means of scores derived by these two methods
of computation. The conclusion drawn from this study is that the
Social Adequacy Index may be used as a valid estimate of the
average discrimination scores of tests at the above mentioned

levels.

AN EMPIRICAL EVALUATION OF
SOCIAL ADEQUACY INDEX FOR HEARING

By

Bari Louise Schoenkerman

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

1965

TABLE OF CONTENTS
Page
LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . iv
LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . "v
LIST OF APPENDICES . . . . . . . . . . . . . . . . . . . . vi
Chapter
I. STATEMENT OF THE PROBLEM. . . . . . . . . . . . . 1

Introduction

Purpose of the Study
Importance of the Study
Definition of Terms
Organization of the Stuiy

II. REVIEW OF TIE LImTUR-Ee O O O O O O O O O O 0 O 10

Introduction =

Development of Speech Hearing Tests

Description and Development of CID Auditory
Tests

Comparison of CID Tests

III. SUBJECTS, EQUIPMENT, AND PROCEDURES . . . . . . . 21

Subjects
Equipment
Material
Procedures

Iv I RESUIJTS AND CONCLUSIONS 0 O O O O O O O O O O C C 27
Results
Product Mbment Correlation Coefficient

t_Test for Related measures
Discussion

ii

Page

V. SWY AND CONCLUSIONS 0 O O O O O O I O O O O O 30
Summary
Conclusions
Implications
MPENDICES O O O O O O O I O O O O I O O O O O O O O O O O y"

BIBIIIOGRAPIIY O O O O O O O O O O O O O O O O O O O O O O 0 Li’ 3

iii

LIST OF TABLES
Table Page

1. Grouping Schedule. . . . . . . . . . . . . . . . 24

iv

LIST OF FIGURES
Figure Page

1. me MtiCfla-tion Area. 0 O O O O O O O O I O O I 2

LIST OF APPENDICES
Appendix Page
A. SocialAdequacyIndex.............. 31+
B.CIDAuditoryTests............... 35
C.AnswerForm..................40
D. Random Order Testing Schedule. . . . . . . . . . 41

EOTableOfScoreSoeeeeeoeeoeeooeoo “'2

vi

CHAPTER I
STATEMENT OF THE PROBLEM

W

A.well known measure in speech audiometry is the Social
Adequacy Index (SAI), devised by Hallowell Davis in 1948 at
the Central Institute for the Deaf (CID) in St. Louis,
Missouri.1 The SAI is a numerical score.which serves as an
estimate of the difficulty which a person encounters in social
situations due to his hearing loss.

Davis developed an average curve for ten normally hear-
ing subjects. This curve is shown in figure 1.

The assumption was made that the shgpg,of the curve would
remain fixed, regardless of the loss sustained by the individ-
ual.2 Davis stated that the following changes would appear as
a result of a hearing loss:

...it the above mentioned curve developed for
normally hearing subjects may be shifted to

 

lH. Davis, "The Articulation Area and the Social Adequacy
Index for Hearing,” Th2 L osco , 58 (1948), 761-778.

ZIbid. , 767.

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-3-

the right by any "flat" hearing loss (conductive

or nerve in any proportion) and/or shifted down-

ward by any non-uniform loss or by any central

failing in the process of discrimination. . . .

The shift downward (discrimination loss) is due

to a failure of the sense organ, nerve, or brain.

It cannot be offset by mere increase in loudness;

but sometimes it can be offset, wholly or in part,

by psychological factors such as auditory train-

ing.3

The SAI, pg}; 533, is an estimate of the mean discrimination
scores obtained at levels approximating faint,normal, and loud
speech. These levels have been arbitrarily defined by Davis as
33 dB, 48 dB, and 63 dB, respectively.“ They are represented
in figure 1 by vertical broken lines. A table of the estimated
average discrimination scores was devised by moving the above
mentioned curve for normally hearing subjects to the right and
down according to the degree of the loss, and averaging the dis-
crimination scores at the three Specified intensity levels.

In developing the SAI scale Davis used test scores obtained
through administration of the Harvard Psycho-Acoustic Laboratory
Phonetically Balanced word lists (PAL PB-50).5 In clinical
situations, however, CID Auditory Tests Wel and'W;22 are usually

administered. According to Newby,

 

3Ibid., 768.
“Ibis. , 761+.
51bid., 763.

.14...

There is considerable evidence that most people will

make higher scores on the'WAZZ test than they could

on the older recordings of the Harvard PB words.6

The CID tests were developed with the aid of more accurate
recording methods. A second factor which was incorporated into
the CID lists was the standardization of the voice heard on the
record. Only one talker was used, and carrier phrases were re-
corded and copied for later records rather than being rerecorded.7
The higher scores may, in part, be due to these changes.

If scores on CID tests are actually higher than those ob-
tained by use of PAL PB-5O lists, then means of these scores will
also be higher. Davis's SAI scale represents the mean of discrim-
ination tests given by administration of the PAL PB-5O word lists;
since the scores are lower, the means will be lower. Because of
this situation the SAI obtained empirically by use of CID tests
may be higher than the SAI derived by the method prescribed by

Davis.

Purpgse 2f_thg Study
It is the purpose of this study to test the validity of the

SAI for ma and w-22 tests by empirically obtaining averages of

 

6Hayes A. Newby, Audiology: Princi les‘ggd Practice, (New York:
Appleton-Century Crofts, Inc., 19555, p. 118.

7I.J. Hirsh, et al., "Development of Materials for Speech
Audiometry," Journal gf'Spgech ggd'Hearing Disorders, 17 (1952),
322.

-5-

discrimination scores on'W-ZZ tests at the following levels:
33 dB, 48 dB, and 63 dB. This experimentally obtained SAI
will then be compared with the SAI obtained by the Davis method.

The following questions have been.formulated, and will be
explored in this study:

1. Is there a.difference between the SAI as estimated
according to the method described by Davis, and the SAI obtained
empiricaILy? The hypothesis of no difference between the means
will be tested by a.t test for related measures.

2. Is the correlation between the two methods of clinical
significance? According to Greene, the following may be said of
correlations falling between .75 and .95; "Good individual pre-
dictions can be made for most of the group, but there will be
some divergence."8 For purposes of this study a correlation
coefficient significantly greater than .75 will be considered

clinically significant.

Importance 2; Egg Stggy
Numerous Speech and hearing clinics in this country are
now using the SAI in audiological evaluations. It is assumed

in these clinics that it provides a useful measure of the com-

 

8E.B. Greene, Measurements gf'Human Behavior, (New york:
Odyssey Press, 1952 , .

-6-

bined effects of a client's speech reception threshold and his
maximum.discrimination score as determined by the particular
clinic. The SAI may be used as a measure to compare the client's
performance on one test with his performance on later evalua-
tions, to compare the relative efficiency of different hearing
aids, and to evaluate the success of various surgical techniques
by the method of before and after testing.

If the method of obtaining the SAI is invalid or unreliable,
however, the comparisons in which it is involved will be of doubt-
ful reliability and validity. If the SAI scores are not true in—
dications of the mean scores of discrimination tests at 33 dB, 48
dB, and 63 dB, they may not provide an accurate measure of the
person's ability to function adequately in society. Davis has de-
fined various criteria for interpretation of teSt results. For
example, the limit for the normal ear is an SAI score between 94
and 100. A patient with an SAI of 67 will begin to notice dif-
ficulty in some situations. The "Threshold of Social Adequacy"
has been set at an SAI of 33. In other words, a patient with an
SAI of 33 or less, will have a great deal of difficulty commun-
icating.9

 

9Newby, 93. 9_i_'_t_., 117.

-7-

These interpretation criteria were, of course, based upon
scores obtained on the PAL PB-5O word lists. The actual clinical
interpretation, however, is usually based on CID auditory tests.
The fact that the criteria are being used on material other than
that for which they were developed, may or may not be of some

consequence. It will surely bear investigation, however.

Definition g§_gggg§

For purposes of this study the terms appearing are defined
in the following manner: A

m Discrimination Iggy-An evaluation of the subject's
ability to discriminate between acoustically similar words or
sounds.

Phoneticgly Balanced--Test items in which all of the somd
groups, 1.9., plosives, fricatives, sibilants, etc., of the
English language are represented. These sound groups appear in
proportions equivalent to their proportions incommon usage.lo

CID Auditory 3233?; &--A discrimination test consisting of
four lists of 50 words. Selection of these words represents a
modification of the Harvard PAL PB-50 word lists.

Endaic MuTwo syllable words, high in vowel content, pro-

nounced with equal, or nearly equal, stress on each syllable.

 

10J.P. Egan, "Articulation Testing Methods," 2132 L osco ,
58. (1948), 990.

-8-

CID Auditog _T_e_§_t_ fluA test developed by CID consisting of
36 spondaic words, presented at a constant intensity level.

ma; Hearing Sibjects--Subjects claiming to have no hearing
loss or otologic pathology.

m Reception Threshold-«The intensity level, in decibels,
re. 1951 ASA standards,11 at which a subject correctly repeats 50
per cent of the spondaic material presented to him.

Discrimination I_.9_§_s_--The percentage of words missed by a
subject to whom CID Atriitor'y Test W-ZZ is presented.

Discrimination _S_q_o_rg--’Ihe percentage of words identified
correctly by a subject to whom CID Auditory Tebt W—22 is presented.

Estimated §AI_--An estimate, computed from the Davis SAI scale,
of average discrimination scores of tests administered at three
levels of speech.

Eerrimental §A_I_--The arithmetic mean of scores obtained in
this experiment on discrimination tests given at selected levels,
i.e., 33 dB, 48 dB, and 63 dB (re. 1951 ASA standards.)

Intensity Reference Egg-Mess otherwise stated all in-
tensity levels stated in this writing are based on a reference

level formulated by the American Standards Association.

Organization p_f_ th Stu_dy I

The organization of this presentation is based on five

 

..llAmerican Standards Association, Specifications for ech

Audiometers, (New York: American Standards Association,; 1953 , p. 9.

-9-

chapters. Chapter I presents a general statement of the problem,
including some background information, the purpose and importance
of the study, and definitions of the toms as they are used in the
study. Chapter II, Review of the Literature, presents a summary of
the body of knowledge in the field of speech audiometry. It in-
cludes a description of the form and development of speech hearing
tests, a brief history of their development, and a detailed des-
cription of the CID Auditory Tests and their relationships to each
other.

Chapter III of this presentation is a detailed description of
the mechanics of the study and the methods usedi'in its administration.
Statistical treatment of the data obtained from'the study is present-
ed in Chapter IV; Summary and Conclusions of the study are presented
in the last chapter. This chapter affords a brief resume of the
purposes, procedures, and results involved in the study. The various
Appendices, A through F, include such charts, lists, and graphs,
which would give the reader a more complete understanding of the

Study 0

CHAPTER II

REVIEW OF THE LITERATURE

Introduction

Of the multitude of sounds which are heard, speech is, by
far, the most crucial for everyday life. Some efforts have been
made to relate pure-tone testing results to hearing for speech,
but a truly reliable and valid measure of these relationships
is not yet availablo.l

Researchers have found that there is some difference in the
ability to hear different types of speech material. Fbr example,
sentences are easier to comprehend than short phrases; phrases
are easier than single words; and words are more easily intelli-
gible than single phonemes.

Differences among test materials with respect to

their intelligibility are due principally to the

fact that some materials require more information
than others for their correct perception.2

 

1H.A. Fletcher, "A Method. of Calculating Hearing Loss for
Speech From.and Audiogram,” Journal 2;.thg Acoustical Society
2; America, 22 (1950), 2.

26. Miller, G.A. Heise, and w. Lichten, "The Intelligibility

of Speech as a Function of the Context of the Test Materials,"
Journal 2;: gperimental P holo , 41(1951), 334.

-10-

-11..

In other words, some words have more auditory "clues" than
others. The greater the number of these "clues" included in a
test item, the greater the chance for its correct identification.

In addition to differences in context of presentation, it
has also been shown that different speech sounds have different
acoustic properties. All voiced consonants, for example, use
the frequencies between 100 and #00 cycles per second.3 v'owels,
semi-vowels, and nasals use frequencies ranging from.#00 to 2fi00
cycles per second.u The high frequency sounds, i.e., fricatives,
stops, and sibilants, depend for production upon the frequencies
between 2400 and 800 cycles per second.5

Aside from the phonemic elements of the sounds themselves,
there are several other factors which must be considered in
developing measures of the ability to hear speech. These factors
will be discussed below.

Pepulation--For whom was the test designed? The test must
be designed with the basic abilities of the population in mind.

General Format--What type of test should it be? There are

a variety of ways in which a response may be made; this, too,

 

3R.N. Plummer, ”High Frequency Deafness and Discrimination
of High Frequency Consonants," Journal gf_§pgech ggd_Hearing
Disorders, 8 (1943), 374.

uIbid.

5Ibid.

-12-

will depend to a large extent upon the abilities of the population
to whom.it is administered.

Scoring-AWhat type of score will be obtained upon presentation
of the test? In the case of Speech audiometry, most scores are
given in percentages of material correct or'incorrect, or'in sen-
sation level of hearing.

Material-AWhat type of item.will be used on the test? What
items will be used? As has been shown, there is a great deal of
variety in the ease with which different materials are perceived.
This must be taken into consideration in item selection.

Presentation--How will the test be administered? Physical
conditions of the room.and testing apparatus, and certain psycho-
logical considerations must be made.

Measurement-AWhat is the examiner trying to measure? Tests
must be designed with a specific purpose in mind. The objectives
of the test must be considered in all phases of its development.

The following measures have been developed in the field of
speech audiometry. Levels are usuaILy stated in decibels re.
1951 ASA standards.

1. Threshold of Detectability--the level at which the
subject is able to detect the presence of sound 50 percent of
the time. In this measurement the factor of intelligibility is
entirely disregarded; the only interest is that the subject is

aware of some sound in the testing room.

2. Threshold of Perceptibility--the level at which the
subject is just able to understand the gist of connected dis-
course with considerable effort. This is usually about 8 dB
above the level of detectability.6

3. Threshold of Intelli gibilitynthe level at which the
subject is able to understand connected discourse with ease.
Generally, this is about 1+ dB above the threshold of percep-
tlblllty.7

4. Host Comfortable loudnessnThe level that is most com-
fortable for the subject. It infers that he is able to under--
stand, to-theemaximum.of his ability, all e: the speech material
presented to him.-

5. Threshold of Tolerance—the level at which the subject
is unable to tolerate additional intensity.

6. Speech Reception Threshold-nthe level at which the sub-
ject is able to hear and identify 50 percent of the spondaic
material presented to him.

7. Discrimination Score-«In most cases this score is

stated as a percentage. It represents the amount of the pre-

 

6J. P. Egan, "Articulation Testing Methods," Mngoscopg,
58. (1948). 980.

7Ibid.

-14-

sented material which the person has heard. Generally, the
material consists of some type of word list, but this need not
always be the case.

8. Maximum Discrimination Score--This measure represents
the percentage of presented speech material which is correctly
heard and understood at the optimum intensity for the subject,
i.e., further changes in intensity would not raise the score.

As has been mentioned, one of the main concerns in test
development is item.selection. According to Hudgins, 25:3l3,
such criteria as phonetic dissimilarity, selection of speech
sounds to be used, and word familarity must be taken into
account.8 Egan believes that words should be monosyllabic
and effort should be directed toward including items of the
same difficulty. All words should be commonly used in con-
versation and writing, thus eliminating educational and cul-
tural factors as much as possible. Wbrds should be of equal
phonetic composition.9 These are factors which should be

considered in item selection.

 

8Hudgins, et al., "Development of Recorded Auditory Tests
for Measuring Hearing Loss for Speech,” The.Laryngoscope, 57
(191+?) . 58.

9Egan, op, cit., 958-960.

-15-

ngelopment g; m Hearing Tests

Bell Telephone Laboratories, in an effort to evaluate the
efficiency of communication equipment, developed one of the
first speech hearing tests. This test, called "The Standard
Articulation Lists," consisted of a series of meaningless
syllables. unfortunately, problems arose in reporting these
sounds, and the test was replaced by a test consisting of a
series of numbers spoken in groups of three.10 This test was
very widely used, and provided material for one of the first
recorded tests for speech hearing. The Western Electric 4A
Audiometer was used to present and administer the tests. The
test was proven to be weak in that it was not fine enough to
discriminate between flat and high frequency hearing 108865.11

A test was developed by Robert'west that attempted to re-
flect losses in high frequencies. Various sounds were select-
ed and grouped according to the auditory frequencies occuring
in the sounds. This test, however, was not very widely used,
due to the fact that it was not a valid measure of the type of

hearing loss for which it was devised.12

 

olonouglas Macfarlan, "Speech Hearing Tests," The
Larmgscope, 55 (1945): 77-

llHudgins, _e_t e_1_., 92. gi_t_., 60.

leacfarlan, 92. 23., 90-91.

-16-

Research by Watson and Knudsen led to the development of a
test designed to measure both the level of speech hearing and
discrimination. The test was administered several times on each
subject. A threshold was determined in the first presentation,
and then it was repeated several times at different intensity
levels, in order to ascertain the percentage of loss present at
each of these levels.13

The "word Hearing Test" developed by Thea.in 1941, present-
ed a group of words which sound alike. The subject indicated
which of the words he heard.1“

During the 1940's the Psycho-Acoustic Laboratory (PAL) at
Harvard university undertook research to accomplish the follow-
ing goals.

1. To investigate the problems inherent in the development
of testing materials for speech audiometry.

2. Tb produce a test, or tests, which would be adequate
for measurement of intelligibility of the English language in
situations of normal hearing as well as hearing loss.

3. To develop some type of test to discriminate between

uniform and high frequency hearing loss.

 

13mm. 93-95.
1“Ibid., 99.

-17-

This research led directly to the construction of PAL
Auditory Tests No. 9 and No. 12. They differ in that the former
provides a measurement for threshold for words, and the latter
deals with sentence intelligibility. A third test, one dealing
with high frequency measurement, was constructed, however, this
was discarded as a diagnostic tool, in.favor of pure tone
audiometry which more accurately differentiates between types
of losses.15

word lists were constructed as a part of the same project.
The lists consisted of monosyllabic words and were designed to
be used in discrimination testing. Wbrds for these 24 lists
were selected on the basis of the phonetic composition of the
first part of the word. These Revised Mbnosyllabic (RM) lists
were partially satisfactory for testing purposes, but the need
for further refinement was seen.

Further refinement took the form of the PAL PB-SO word
lists. Each of the four lists contains 50 words. These words
have been selected on the basis of sound groups and appear in

proportion to their usage in common English.l6

o.

 

15Hudglns, 5211,, 92. 333., 62—64.

16Egan, 92. 31.3., 962-964.

-18..

Description and Development of CID Auditoryzggtg

The Central Institute for the Deaf, St. Louis, Missouri, has
used the PAL materials as a basis for its series of auditory tests,
i.e., w;1,'w;2, and W;22. They are recordings based on the PAL
materials incorporating certain refinements and improvements. First
of all, these tests have restricted the vocabulary more rigidly,
and, thus, the words must meet more strict criteria. Phonetically
balanced lists, used in‘WLZZ tests, have been more finely balanced
so as to give a truer sample of English speech.

The second major refinement has come as the result of more
modern recording techniques. The utilization of magnetic tape has
made it possible to standardize the recordings to a greater extent.17
Specifically, these refinements have brought about the development
of the tests which will be described below.

CID Auditory Test WLl--This test consists of Spondaic words
recorded at a constant intensity level; the actual intensity level
of these words varies only :2 dB. Preliminary test results in-
dicate that, for normal listeners, the intelligibility curve
rises from 0 to 100 percent within a range of about 20 dB.18

CID Auditor Test'ws2--This test is made up of spondaic

 

17I.J. Hirsh, gt.gl,, "Development of materials for Speech
Audiometry," Journal 9§_§p§ech andDHearing Disorders, 17 (1952),
322.

181bid., 323-326.

-19-

words recorded at a changing intensity level; the intensity is
attenuated at the rate of 3 dB every three words. In other words,
three words are recorded at level X, three words at level X-3 dB,
etc. Threshold scoring assumes that the intensity is attenuated
one dB per word.19

CID Auditory Test‘W;22-This test is made up of one syllable
words, 200 in number, divided into four lists of 50 words each.
There are six scramblings of each recorded list. Phonetically
balanced word lists were emplqyed in development of these testing

materials.20

Comparison of CID Tests

The average threshold for‘W;2 (changing intensity) was
approximately 4 dB above that for‘Wel (constant intensity).
This seems to be due to the differences in the number of words
presented at each level, and the error inherent in the assumption
of one dB attenuation per word on the‘WLZ recordings.21

The intelligibility of spondaic words increases more rapidly
as a function of intensity than does the intelligibility of PB

words. Thus, speech reception thresholds for spondaic words are

 

l9mm” 326-328.
2OIhid,_, 328-329.
21mm. 333-335.

 

 

-20..

somewhat lower than for PB's.22

The general reliability of these testing materials is quite high.
Preliminary test results show no more errors than would be expected
to occur in a random.sampling.23

Research is still in progress in order to develop better
methods for evaluating hearing for speech. Materials are constantly
being developed, refined, and tested. Our methods are still not
adequate for making all the fine differentiations between hearing
difficulties. To reach the optimum in hearing testing methods,

more research is needed.

 

22Ibid.

23Ibid., 331.

CHAPTER III

SUBJECTS, EQUIPMENT AND PROCEDURES

In carrying out this experiment 24 subjects were tested.
A description of the subjects, equipment, and testing materials

and procedures employed follows.

m
The subjects for this study consisted of 24 Michigan State

University students. These subjects, ten males and fourteen
females, ranged in age from 18 to 30 years. All reported normal
hearing. These participants were not familiar with CID tests or

testing procedures.

Equipment

Two tape recorders were used in preparation and presentation
of the test materials. An Ampex, Model 601 tape recorder was em-
ployed to make the original transcriptions of CID Auditory Tests;
these tapes were presented to the subjects via a Wollensack, Model
1500 tape recorder and an Allison, Model 20 A, clinical audiometer.
Filtering of test material was achieved with the aid of an Allison

Audiometer Filter, Model 25.

-21-

-22..

Materials
Filtered recordings were employed in order to obtain the
test scores for use in this study. Speech reception thresholds
were obtained through the presentation of CID Auditory Test W-l,
List E. Discrimination tests made use of CID Auditory Test W-22,
Lists 1A, 2A, 3A, and 4A, (Appendix B). Answer forms were pro-

vided by the examiner, (Appendix C).

Procedures

Preliminary Procedures

The CID tests W-l, ListE, W-22, Lists 1A, 2A, 3A, and 4A,
and a calibrating tone for each, were transcribed onto magnetic
tape with the aid of an Ampex, Model 601 tape recorder in the
Speech and Hearing Science Laboratory of Michigan State University.
Five tapes were recorded, filtered at the following levels:

Tape 1: No filtering was used. Words were recorded just
as they are heard on the CID recordings.

Tape 2: Frequencies above 2400 cps were eliminated.

Tape 3: Frequencies above 1200 cps were eliminated.

Tape 4: Frequencies above 600 cps were eliminated.

Tape 5: Frequencies above 300 cps were eliminated.
This last tape was used on one subject only; it was deemed too
difficult to be included in the study. 80 few of the speech sounds
remained that it was impossible for the examiner to obtain a speech

reception threshold or administer a discrimination test.

-23-

The above mentioned frequency cut-off levels represent the
point of major frequency out off. Due to the nature of the Allison
Audiometer Filter all intensities of frequencies above the cut-off
point are attenuated at the rate of 30 dB per octave.

All subjects were questioned as to their otologic histories.
The following questions were aSked:

1. Do you have any type of hearing loss or impairment?

2. Have you ever had any type of hearing loss or im-
pairment?

3. Have you ever had "ear trouble" of any type?

4. Do you have any trouble hearing in everyday situations?

Subjects were accepted for testing only if all answers to the
above questions were negative.

All subjects were divided into groups and subgroups, according
to the series of tests they were to receive. Table 1 indicates the

grouping schedule.

-24...

TABLE 1

GROUPING SCHEDULE

 

 

 

Low Pass
Group No. of Subj. Filter Cut-Off Condition
la 3 None No Noise
2a 3 2400 cps No Noise
3a 3 1200 cps No Noise
4a 3 600 cps No Noise
lb 3 None 50 dB Noise
2b 3 2400 cps 50 dB Noise
3b 3 1200 cps 50 dB Noise,
4b 3 600 cps 50 dB Noise

 

All testing was done in the Speech and Hearing Clinic,
Michigan State University. The stimuli were presented in sound

field.

Testing Procedures
A speech reception threshold was obtained for each subject,
using-the previously made tape recording of CID Auditory Test
Wel, List E, which had filtering and masking appropriate to the
group to which the subject had been assigned, i.e., Group la, 2a,
lb, 2b, etc. Oral responses were given by the subjects.
Prior to presentation of this material, the following directions

were given orally to the subjects:

-25-

You will hear a series of English, two-syllable

words; you repeat them as you hear theme (When

necessary, examples were given.)

A speech reception threshold test was then administered.

The examiner then entered the testing room and gave the sub-
ject a test answer form (Appendix C). The following verbal in-
structions were given:

Ybu.wi11 now hear four'more lists of English words.

Again the voice on the tape will say, "You.wi11

say..." This time you are to waitg_the word that

you hear.

A series of four discrimination tests was then administered.
Auditory Tests were presented in a standard order to all subjects,
i.e., List 1A, List 2A, List 3A, and List 4A.

In order to eliminate the effects of fatigue, the intensity
levels were varied according to a preselected random order
(Appendix D). Presentation was made at the following intensity
levels, re. 1951 ASA standards.

1. SRT 40 dB--This level was used to represent maximum
for PB words in all cases.

2. 33 dB--This level was indicated by Davis to represent
the level of "soft" speech.

3. 48 dBn-This level was indicated by Davis to represent
the level of "Average" speech.

4. 63 dB--This level was indicated by Davis to represent

the level of "loud" speech.

-26-

Scoring Procedures

Estimated SAI-u-This measure was determined by the results of the
speech reception threshold test and the PB maximum score. These
scores were then applied to a table developed by Davis (Appendix A),
and the SAI was computed in the manner prescribed by him.

Experimental SAL-Scores on the remaining three discrimination
tests were arithmetically added and divided by three in order to

arrive at the numerical average, or mean, of the test scores.

CHAPTER IV
RESULTS AND DISCUSSION

3.22.212

The results were tabulated and treated in two'ways. Comp
parison of the two methods of computing the SAI, i.e., Davis's
method and the experimental method, was made by two statistical
treatments: 1) A product moment correlation was computed, and
2) Differences between the test scores were tested by a‘t test

for related measures. These methods will be described below;

Product Moment Correlation Coefficientl

The two methods of SAI computation were compared by the
product moment correlation method. A high, positive correlation
of .94 was found between these two methods. This would infer
that the experimentally obtained SAI can adequately be predicted
from the estimated SAI. Hence, it would.not be necessary to

obtain SAI's by the empirical procedure.

 

lHubert Blalock, Social Statistics (New York: McGraw-Hill
Book Company, 1960), p. 257.

-27-

-28...

t Test for Related Measuresz

A‘t_test for related measures was applied to the differences
between the SAI values obtained by the experimental method and
those derived by the estimated method. Mean scores were 49.3 for
the former and 48.0 for the latter.

Since alt_ratio of 1.714 or larger is needed to indicate a
significant difference at the .05 level, the‘t ratio of .016,
derived from these data indicates that the mean difference in test

scores for these two methods is not statistically significant.

Discussion

The product moment correlation coefficient was designed to
determine to what extent the experimental SAI test which was
administered to the subjects, is related to the estimated SAI.
The high, positive correlation of .94 was found for the two
methods. This seems to indicate that the methods are related.
For example, a subject obtaining a given score on the experimental
SAI scale, will do similarly on the estimated SAI scale. The re-
verse of this would also hold true.

In order to reject the null hypothesis that the mean SAI

 

21bid., 181.

-29-

values for methods would be the same, a t_ratio of 1.714 or higher
is needed. Since the t_ratio in this case is only .016, it may be
said that the two SAI values are not significantly different. In
other words, the high, positive correlation and the low't_ratio
both tend to indicate similarity between these two methods of de-
termining the SAI.

The results of these statistical treatments tend, for the most
part to indicate that Davis's method of estimating the average of
discrimination scores obtained at given intensity levels is closely
related to this type of average when it is obtained empirically. If
this is the case, then the estimated SAI computation should be an
adequate method of determining this type of average. Differences
between testing materials and testing procedures, as well as
derivational methods used by Davis in the original study, and those
used by the present writer in this study, seem not to have pro-
found influence on test score results, when such results are ob-

tained under the conditions specified in this writing.

CHAPTER V

SUMMARY AND CONCLUSIONS

_
In the past there have been several attempts to evaluate and
assess the efficiency of a client's hearing. One of the best
known of these measures is the Social Adequacy Index (SAI) develop-
ed by Hallowell Davis in 1948. Speech reception thresholds and
maximum discrimination scores were obtained for each subject.
These scores were then applied to the SAI table (Appendix A) which
gave a numberical score representing the average discrimination
scores at 33 dB, 48 dB, and 63 dB, re. 1951 ASA standards. Davis's
scale was developed by transfering the normal articulation curve
to a statistically derived scale and plotting the results. The
present study tests the validity of this statistical information
by determining and averaging actual discrimination scores obtained
at the above mentioned levels and comparing them.with results ob-
tained by way of the SAI table.
TWenty-four Michigan State university students participated
in the experiment. Each was given a speech reception threshold

test, using CID Auditory Test Wel, List E, and four discrimination

-30-

-31-

tests, using CID Auditory Tests'WLZZ, Lists 1A, 2A, 3A, and 4A.
The discrimination tests were presented at levels of 33 dB, 48
dB, and 63 dB, re. 1951 ASA standards, as prescribed by Davis,
and at a level representing Most Comfortable Loudness (SRT-+
40 dB) to obtain a maximum PB score.

Four tapes of test material were prepared with different
levels of filtering, i.e., low pass filtering was introduced into
the system. Due to the nature of the filter which was used, all
frequencies above the given cut-off point are attenuated at the
rate of 30 dB per octave. The cut-off points for filtering were
as follows: 2400 cps, 1200 cps, 600 cps, respectively, on the
three distorted tapes, and no filtering on the fourth tape.

TWelve of the subjects received the test under quiet conditions.
To the remaining twelve the test was administered in the presence
of white noise at 50 dB SPL.

Discrimination scores were averaged to obtain the experimental
SAI. The SRT and maximum discrimination score were applied to the
SAI table (Appendix A) to obtain the estimated SAI. The SAI's ob-
tained by these two methods were then statistically compared to
determine the degree of correlation between them and whether or
not there was a difference between their means. Actual means were
49.3 for the experimental SAI and 48.0 for the estimated SAI.

Results show that there is a high degree of correlation
(+.94) between the two methods of SAI computation. This corre-

lation yields an F ratio of 167.00, significant at the .05 level.

-32-

Confidence limits at the .05 level for this correlation, derived
by the method of Fisher's Z transformation, are at a lower limit
of .86 and an upper limit of .97. A.non-significant difference
between the means was shown by a t,ratio of .016. The statis-
tically computed scores of the Davis scale may therefore be said
to be a useful estimate of the average discrimination scores

obtained empirically.

Conclusions

Within the limits of this study, the following conclusions
may be drawn: ~

1. The difference between the mean scores for the SAI com-
puted by the experimental method (49.3) and those computed by the
Davis method (48.0) is non-significant at the .05 level.

2. The correlation between the two methods is positive and
greater than .85 at the .05 level of confidence. It may, there-
fore, be assumed that the relationship between the two methods is

predictive and has clinical importance.

Implications for Further Research
This study has used normal-hearing subjects who have listened
to distorted material. It is known, however, that filtering, noise
and other distortions, do not really represent the effects of a
hearing loss. There are many other factors that may influence the
real effect that a hearing.loss will have. Further evaluation of

the SAI might well be directed toward utilizing some of these

-33-

other distorting factors, i.e., different filtering patterns may
be used, time distortion may be introduced by playing material
faster or slower, or phase distortion may be employed to modify
the test material. Since even these distortion patterns are not
really able to imitate a sensorineural loss, a population might

be tested which has some type of loss.

34

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-35-

Appendix B

 

northwest
doormat
railroad
woodwork
hardware
stairway
sidewalk
birthday
farewell.1
greyhound
cowbqy
daybreak
drawbridge
duckpound
horseshoe
armchair
padlock

mousetrap

CID AUDITORY TESTS

W’l , “St E

headlight
airplane
inkwell
grandson
workshop
hotdog
oatmeal
sunset
pancake
eardrum
mushroom
whitewash
hothouse
toothbrush
playground
baseball
iceberg

schoolboy

yard
carve
us
day
toe
felt
stove
hunt
ran
knees
not
mew
low
owl
it
she
high
there
earn
twins
could
what
bathe
ace

-36-

'W¥22, List 1A

you
as
wet
chew
see
deaf
them
give
true
isle
or
law

none
jam
poor
him
skin
east
thing
dad
“P
bells
wire
ache

your
bin
WEY
chest
then
ease
smart
gave
pew
ice
odd
knee
move
new
jaw
one
hit
send
else
tare
does
too
cap
with

-37-

‘WLZZ, List 2A

young
c ars

dumb
that
die
show
hurt
own
key
oak
now
live-
off

rooms
ham
star
eat

flat
well

 

bill
add
west
cute
start
ears
tan
nest
say
is
out
lie
three
oil
king
pie
he
smooth
farm
this
done
use

camp

-38—

W¥22, List 3A

when
book
tie
do
hand
end
shove
have
owes

no

knitt
on

if
raw
glove
ten
dull
through
chair
we
ate
year

 

wood
at
where
chin
they
dolls
so
nuts

ought
not

leave
of
hang
save
ear
tea
cook

bread
why

yet

W-ZZ , 10151.; “A

darn
art
will
dust
toy
aid
than
eyes
shoe
his
men
near
few
Jump
pale
go
stiff
can

through
clothes

who
bee
yes
am

aid

 

-40-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix C
ANSWER FORM
Name Subject number
Group . Test orderw T
dB level
1 26
2 27
3 28
4 a— a 29 . i -
5 g _ao
6 31 g? g
7 32 fl _
8 A33 -_
9 T 34 g
10 ‘ 35
ll 36 I—
12 +37fi—‘ U W
13 . . 38 a w aw we
14 I If ‘7 39 “
15 a 40 i W - “h
16 I ‘ 41 _- T V
17 I: 1+2
18 I -_ I 43 W T If “I
19 ' 44
20 45
21 V 46
22 447g
23 48 -
24 jg

 

-41-

Appendix D

 

RANDOM ORDER TESTING SCHEDULE

Test l-Discrimination test at SRTW40 dB.
Test 2-Discrimination test at 33 dB.
Test 3-Discrimination test at 48 dB.
Test 4-Discrimination test at 63 dB.

 

 

nil-l a '

 

 

subject Number Test Order
1 3142
2 3142
3 2431
4 3241
5 2413
6 3421
7 4321
8 1243
9 2134
10 4312
11 4312
12 3421
13 4321
14 2413
15 4132
16 3241
17 1243
18 3124
19 4132
20 4132
21 1432
22 4312
23 4213
24 4132

—42-

Appendix E

 

TABLE OF SCORES

 

 

Subj.No. SRT Disc. Disc. Disc. Disc. Disc. Est. Exp.
. . Loss Score O33dB 048dB O63dB SAI SAI

 

1 -5 14 86 96 96 98 84 92
2 -5 6 94 9o 94 94 94 93
3 -5 2 98 92 78 94 99 88
4 -5 6 94 94 94 92 94 93
5 10 4 96 82 98 96 89 92
6 -5 6 94 9o 92 96 94 93
7 -5 46 54 58 62 52 55 57
8 -5 54 46 56 54 66 45 59
9 -10 50 50 42 58 60 50 53
10 10 9o 10 18 4o 10 10 23
ll 35 90 10 16 6 6 8 9
12 25 78 22 16 20 28 23 21
13 3o 18 82 8 56 82 53 49
14 3 5 22 78 14 18 76 46 36
15 30 10 9O 16 64 88 57 56
16 35 30 7o 14 58 72 48 48
17 35 16 84 10 6o 74 47 48
18 36 4 96 34 62 78 51 58
.19 35 74 26 18 24 34 18 25
20 35 56 44 12 4o 38 29 3o
21 35 58 42 0 28 52 26 29
22 35 80 20 14 14 1o 16 13
23 3o 94 6 12 14 14 9 13
24 3o 96 4 8 6 8 9 7

 

Biblio graph!
Book 5

Blalock, Hubert. Social'Statistics. New York: McGraw-Hill Book
Co., Inc., 1960?

Davis, Hallowell, and Silverman, R. Hearing 93d Deafness. New
York: Holt, Rinehart, and Winston, Inc., 19 o. "

Greene, Edward B. Measurements 23 Human Behavior. New York:
Oiyssey Press, 1952.

Hirsh, I.J. The Measurement 3;: Hearing. New York: McGraw-
Hill Book Co., Inc., 1952. J

 

Newby, Hayes A. Audiology: Principles and Practices. New York:
Appleton-Century Crofts, Inc., 19?.-

Senders, Virginia L. Measurement and Statistics. New York:
Oxford University Press, 1958. .

Stevens, 8.8. (ed.) Handbook gt; quelimental Pacholog.
New York: John Wiley and Sons, Inc., 1951.

Articles and Periodicals

Davis, Hallowell. "The Articulation Area and the Social Adequacy
Index for Hearing," The Laryngoscope, LVIII (1948), 761-778.

Egan, J.P. "Articulation Testing Methods," 1113 Lgmgoscope,
LVIII (1948). 955-991.

Fletcher, H.A. "A Method of Calculating Hearing Loss for Speech
from an Audiogram," Journal 21; the Acoustical Society 2;;
America, XXII (1950), 1-5.

Fletcher, H.A., and Steinberg, J.E. "Articulation Testing Methods,"
8811 System Technical Journal, VIII (1929), 806-854.

Fowler, E.P. "Method for Measuring the Percentage Capacity for
Hearing Speech," Journal 2; the Acoustical Society 21: America,

XIII (1942) . 373-382.

.43-

.44-
Hirsh, I.J. "Clinical Application of Two Harvard Auditory Tests,"
Journal.p£.§pgech Disorders, XII (1947), 151-158.

, gt,§l, "Development of Materials for Speech Audiometry,"
Journal pf Spgech and Hearing Disorders, XVII (1952), 321-337.

 

Hudgins, C. V., pp 3;. "The Development of Recorded Auditory Tests
for Measuring Hearing Loss for Speech," The Laryngoscope, LVII
(1947) 9 57-89.

Macfarlan, Douglas. "Speech Hearing and Speech Interpretation
Testing," Archives 21; Oto-lam lo , MI (1940), 517.

. "Speech Hearing Tests," in; paryngoscope, Lv (1945),
71-115.

 

Miller, G., EEHél- "The Intelligibility of Speech as a Function
of the Context of the Test Materials," Journal p£,Experimental
P cholo , XLI (1951): 329-335.

Plummer, R.N. "High Frequency Deafness and Diécrimination of High
Frequency Consonants," Journal p§_§peechigpd Hearing Disorders,
VIII (1943) . 373-381.

Silveman, 3.11., and Hirsh, LJ. "Problems Related to the Use of
Speech in Clinical Audiometry," Annals p£_Otology, Rhinolo ,
as}. L o1o , LXIV (1955). 1273—2-12 5.

Silverman, S.R.,_gt_al. "Improvement of the Social Adequacy of
Hearing Following the Fenestration Operation," The Laryngoscope,
LVIII (1948), 607-631.

Reports

American Standards Association. Specifications £23 Speech
Audiometers. New York: American Standards Association, 1953.

Unpublished Material

Allison Laboratories, Inc. "Allison Mbdel 25 Filter," La Habra,
California, 1962.

 

MICHIGAN STATE UNIVERSITY LIBRARIES

IIHLIIIIIIIIII I

69 5145

I ‘A

3 1293 03