Dept. for Speech, Music and Hearing

Quarterly Progress andStatus Report

Some psychoacoustic testswith hearing impaired

childrenMartony, J.

journal: STL-QPSRvolume: 15number: 2-3year: 1974pages: 072-089

http://www.speech.kth.se/qpsr

STL-QPSR 2-3/1974 72.

D. SOME PSYCHOACOUSTIC TESTS WITH HEARING IMPAIRED CHILDREN

J. ~ g r t o n y

Abstract

Psychoacoustic tes t s can give valuable information for pedagogical and technical rehabilitation of hearing-impaired subjects. The two tes t s de- scribed he re give a contribution to the development of such tests . 1) The intensity-discrimination t e s t showed la rge variations of DI between the sub- jects and no correlation between DI and hearing los s (more than 85 dB ). m 2) The F1 discrimination l imen showed increasing values with increased hearing loss . A decrease of the discrimination l imen with the age could be observed for both tests .

1. Introduction

Different psychoacoustic tes t s such a s pure-tone audiometry, the SISI-

tes t , the Fowler loudness-balance tes t etc. a r e used in audiology. These

tes t s have a s a rule been developed for the diagnosis of type and degree of

hearing loss. Apart f rom this medical diagnosis there is a l so a need fo r

tes t s that can give help in selecting the best hearing aid o r to select the

best training procedure. The tes t s used in audiology can therefore be

divided into the following three categories:

(1) t e s t s for medical diagnosis;

(2) t e s t s for technical diagnosis;

(3) t e s t s for pedagogical diagnosis.

The main pa r t s of the t e s t s used have been developed directly for med-

ica l diagnosis even if they to some extent a l so can be used for technical and

pedagogical diagnosis. One of the most important t e s t s for technical diag-

nosis i s the measurement of discomfort level. These data make it pos- I

sible to select a hearing aid with suitable output power and especially to

avoid too powerful aids. The need for tes t s that give information about I

the most suitable technical a id and training procedure is especially im-

portant in the case of a severe prelingual hearing los s o r a prelingual

deafness.

In many cases i t i s assumed that if a pure-tone audiogram can be ob-

tained it a l so means that the child has a useful residual hearing and that a

powerful acoustic amplification with auditory stimulation is the best aid.

This view has been questioned by several investigators (Rasler 1957;

Nober 1967, 1970; Risberg 1968, 1974). These investigations show that

the threshold in pure-tone audiograms i s in some cases not a hearing

threshold but a vibration threshold. In such cases a tactual stimulation

STL-QPSR 2-3/1974

a s fo r example that one Boothroyd (1972) used can be superior a conven- ' .

tional hearing aid. At present there i s no standard t e s t available to

measure the hearing capacity of profoundly hard of hearings and deafs. , '

2. ~ i y c h o , $ c ~ u s t i c measurements with hearing impa,il'qd , . <

Most of the psychoacoustic t e s t s are kneabbrements on intensity dis-

criminatioh limen, Tes t s of these types a r e developed by for instance Denes

& Naunton (1950): Lilscher (1951); f e f p e r et a1 (1959). Some of the

measuliements have been further developed and a r e clinically used for I diagno sia of recrui tment& The investigation$ a r e made mainly on adults

with moderate to severe hearing losses . I

Measurements of frequency discrimination have been made by f a r 1 instance DiCarlo (1962) and Gengel (1969). Gengel was interested in

the training effect, He used two gr'oups of subjects (age 10-17 years)

with audiograms of type (1) A2 and (2) B C / ~ (Risberg and ~ h r t o n y 1972).

aengel found c lear training effects for the group B C / ~ . He found a

moderate correlation between hearing los s and discrimination l imen for

f = 500 Hz but not a t 250 Hz. On basis of the resu l t s he recommended in-

tensified auditory training.

Mazbas (1968, 1972) measured discrimination l imen for intensity (DI),

frequency (DF), and t ime (DT) and calculated the hearing capacity. On

bas is of these resu l t s speech training was made with some subjects using

an especially deviced vocoder (Pimonow 1968). ~ a z & a s made even a com-

parison between hearing capacity and how much the subjects benefitted

f rom the hearing aids. F o r hearing capacity below 2000 bits/sec no bene-

fi t f rom the hearing aid could be obtained. ~ a z k a s shows correlation I

between hearing capacity and DT but not with DI o r DF.

Psychoacoustic tes t s with speech- sound like stimuli have been made 1 by Pickett and Mhrtony (1970) on the discrimination l imen of f i r s t formant

frequencies in stationary vowels (see par t 4. F i r s t , formanefrequency dis-

crimination). Measurements on discrimination l imen fa r the second for- I mankfrequency transition was made by Martin e t a1 (1972); Danaher e t a1

(1973); Danaher and Pickett (1974). A ve ry interesting finding in these

experiments i s the masking effect of Fl and F2. This finding can in-

fluence the construction and fitting of the hearing a ids (attenuation of low

frequencies, dichotic presentation etc . ) . Experiments on the discr imina-

tion of fi l tered noise has been made by Pickett e t a1 (1965) ; Pickett and

I

STL-QPSR 2-3/1974 74.

Martin (1968). In the experiments the discrimination ability between

low-pass filtered noise (variable cutoff frequency) was measured. In ex-

periments by Gabrielsson et a1 (forthcoming) band-pass filtered noise is

used for the theoretical evaluation of a frequency-transposing amplifier

of system Johansson (1961). Subjects in all these tests were hearing-

impaired college students o r adults with moderate o r severe hearing 1 losses. One exception i s Gabrielsson' s experiments where only normal

hearing subjects were used. \

At the Dept. of Speech Communication, KTH work on psychoacoustic

tests has been going on since 1967. The interest for these tests arose a s

a result of the work on tactile speech transmission (Pickett 1963; Risberg

et a1 1965). The results from experiments with a tactual vocoder showed

that the subject after training could discriminate some speech sounds through

the tactual sense. Teachers of the deaf, however, suggested that the same

o r better discrimination could be obtained when acoustic stimulation was

used. This discussion started the work on measuring the hearing capacity

a t severely and profoundly hearing handicapped school children. Of

special interest in these measurements were the diagnosis of total deaf-

ne ss and how the results in psychoacoustic tests could be used in the re-

habilitation of prelingual hearing-impaired children. I

At present experiments have been made with three types of tests: 1 (1) the identification of a signal a s periodic o r non-periodic, Ris-

berg 1968;

(2) the measurement of intensity discrimination; I

(3) the measurement of the f i r st formant-frequency discrimination.

The results from the last two measurements will here be described and

discussed in detail.

3. Intensity-discrimination limen (DI)

3. 1 Introduction --------a-

Prosodic o r suprasegmental features have a very important role a t

speech perception (~vensson 1974). Table 11-D-I shows the three features,

their acoustic manifestation and linguistic function (Lehiste 197 0).

Table 11-D-I. Supramental features after Lehiste (1970).

Feature ) Acoustic manifestation Linguistic function 1

Quantity, Tempo Quantity f.

- -"-- U

Time dimensions of the acoustic signal

STL-QPSR 2-3/1974 . >

In this test we investigated normal hearing and profoundly hearing-

impaired subjects ' ability to discriminate between different intensities

(s t ress features) of sinusoidal signals. From the test results conclu- 1 sions can be made on the upper limit of s t ress perception in auditory

perception of speech but even some conclusions on the u s e of compression

in hearing aids.

Tests have been made on: I I

(I) normal-hearing subjects with a c o u s t i ~ dtirhulation for investigation of "normal" DI a s a function of age;

(2) normal-hearing subjects with tactual stimulation; 1 (3) hearing-impaired subjects. I Stimuli and test procedure were the same in the three tests. I

I

3. 2 Stimuli ------- I

The test stimulus contained a pair of sinusoidal signals with the same

intensity o r intensity differences of A I dB. The signals approximated

then the vowel-consonant-vowel sequence a s "heard" by a severely hard

of hearing person, where the sinusoid tone represents the vowel and the

silent interval represents a voiceless consonant. The signal duration of

each signal was T msec and the silent interval between them was 1 t ' = 150 msec, which i s the approximate duration of a voiceless conso-

nant o r a group of consonants, see Fig. 11-D-I. In the experiment we

measured the minimal T necessary to discriminate a given A I . The

signal duration T could be varied from 500 msec to 15 msec and the in-

tensity difference A I was varied from 8 to I dB. Test frequencies were:

250 Hz, 500 Hz, 1 kHz, 2 kHz. The stimuli were presented to the listen-

eratthemostcomfortablelisteninglevel, i .e . a t 6 0 t o 7 0 d B S P L f o r

normal-hearing subjects and a t I1 0-120 dB SPL for hearing-impaired ~ subjects.

Lists of 10-12 test stimuli with the same parameters ( d I , T , f) were

presented to each subject who was asked to decide whether the two tones

of the stimulus had the same o r different intensity. After each answer

the subject got information whether the given answer was correct o r not.

If the answers were correct in 75 O/o or more of the cases we can assume

that the subject can discriminate A1 at the given T.

STL-QPSR 2-3/1974 76.

1 kHz 2 kHz

Stimuli combination: 1. 2.

Fig. 11-D- I. ~ e s t st imuli for intensity-di scrimination measurements .

I I I I+AI

I+AI I I+AI IeAI

I

In such c a s e s T was made sma l l e r until the discrimination l imen

was reached. Several runs were made in o r d e r to obtain the final

l imen value. After such s e r i e s A I was changed to a sma l l e r value I

until A I = I dB had been reached. 1

some diff diff 'same

After th is the en t i re measur ing procedure was repeated with a I different frequency. The following o r d e r of f rcquency presentation 1 was followed: I) 5C0 Hz, 2) 250 Hz, 3) I kHz, 4) 2 kHz. Fig.

11-D-2 shows the block d iagram f o r t h e t e s t equipment. The signal

combination i s chosen manually.

3 .4 DI a s a function of a j e ------------- - In severa l investigations (Sic.gentha1t.r 1969; Soderquist and I

Moore 1970 etc.) i t has been shown that hearing threshold, speech

perception, pitch discrimination etc. change with age . In th is par t

of ou r exper iments we investigated DI a s a function of age.

r

-ATT I 1

Stim. combb 1 1 1 2

r+ar 2 2 1 - ATT A 2 2 b

r

GATE 1 GATE 2 TDH 39 b i

b . J

START TI T t i T

Fig. 11-D-2. Block diagram of test equipment for the intensity discrimination measurements.

- -- -

NORMAL HEARING

0 HARD OF HEAR1 NG

I I I I I I I I I I #

7 8 9 10 11 12 13 14 15 16 years

AGE

1 I I I I I I I I I 1

7 8 9 10 11 12 13 14 15 16 years

AGE

Fig. II-D-4. Discrimination limen for intensity a s a function of age f o r normal hearing and severely hard of hearing subjects. a: f = 250 Hz, b: f = 1 kHz, signal duration T = 100 msec .

I

--

STL-QPSR 2-3/1974 78.

for the measured frequencies (250 Hz, 500 Hz, 1 kHz) shows slightly

higher values than for acoustic stimulation a t subjects above 11 years .

3 ._6 _Inttgn_sity= &i ~ c ~ i _ m ~ n ~ t ~ l_ime_A~11 a_t &caaying_i_mpair_e& @?-)-sgbje ct s - - - 3. 6. 1 Subjects

I

The subjects were 26 severely hard of hearing school children aged

10-17 years . Hearing losses of the subjects and audiogram type accord-

ing to the classification system of Risberg-Mkrtony (1972) a r e shown in

Table 11-D-11.

Table 11-D-11. Audiogram type (AT) and hearing loss (mean) of the subjects,. I

All the subjects had prelingual hearing los s and were well trained to 1 participate in psychoacoustic tes ts . F o r three of the subjects no meas -

I

urements could be made a t 1 kHz since there was no audiometric response

o r since the dynamic range a t this frequency was too small . Measure-

ments a t 2 kHz could be made only on six subjects. Five subjects had no

response and four subjects had too small dynamic range a t this frequency.

The end of the school year o r i l lness were the reasons for not measuring

ten subjects a t 2 kHz. 1

3. 6 . 2 Test procedure in t e s t s with HI

There were no difficulties in carrying out the test . F o r some younger

subjects extra introduction was necessary which was given by using pic-

tu res which visualized the intensity change in the stimuli. Reliable tes t

resu l t s could be obtained af te r 1-2 test sessions. Each session lasted t

about 20 min, about two t e s t s were made per week during 4 - 6 weeks.

3. 6. 3 Results in DI t e s t s with HI

The variation of DI between the subSects was much grea ter compared

with normal-hearing subjects. Anyhow, for the hard of hearing subjects

STL-QPSR 2-3/1974 7 9 .

I

I the same type of DI shift could be observed. Fig. II-D-4 shows the

minimal discriminable intensity changes for signal duration T = 100 m s e c

and frequencies f = 250 Hz, 1 kHz a s a function of age. The measured

values var ied f rom 1 to m o r e than 10 dB. The change of DI a s a con-

sequence of the perceptual maturation seems to be a t the ages 12-13

yea r s , i. e. somewhat l a t e r than for normal-hearing children. There

i s no significant correlation between any of the hearing threshold data

(dBm) and discrimination l imen for our subjects. By studying a l l the

collected DI values the subjects could be a r ranged in one of the following

three groups: I

I

(a) increased sensitivity (the DI i s lower than for normal-hearing persons of the same age group);

(b) normal sensitivity (the same DI a s for normal-hearing persons of the same age group); 1

(4 decreased sensitivity (higher Dl than for normal-hearing persons of the same age group).

I There a r e sometimes difficulties in placing a subject in the cor rec t Dl ,

group because of the delayed DI change with age and the grea t individual

variations. ,

Fig. II-D-5 shows the boundaries between the three groups for dif-

ferent intensity discrimination ability for younger and older subjects. i Increased sensitivity group (Group a). 32 % of a l l subjects have an in- 1 creased sensitivity a t f = 250 Hz and 43 yo a t 1 kHz. Four subjects (15 %) belong to Group a for a l l measured frequencies. The belonging to this

group indicates that the subject has residual hearing in the measured f r e -

quency range, anyhow with non-normal discrimination ability. I Normal sensitivity group ( ~ r o u p b). 52 70 of a l l subjects belong to this 1 group a t f = 250 Hz and 39 70 a t 1 kHz. The belonging to this group does

not indicate that the subject has residual hearing, because "normal" DI 1 can be achieved even by the tactual sense only (see 3. 5). Four subjects

(15 %) belong to Group b for a l l measured frequencies.

Decreased sensitivity group (Group c). The subjects that belong to this , group have either an auditory o r a tactual discrimination system (by

stimulation in the ear ) which function correctly. Only one subject be- I

longs to this group for a l l measured freqqencies; for this subject we

might a s sume a general perceptual disorder . Other subjects belong to 1 this group for only one o r two of the measured frequencies, and i n this

case fur ther investigations should be made.

i STL-QPSR 2 - 3/1974

Table 11-D-I11 shows to which group the subjects belong for the f re -

quencies 250 Hz and i kHz. At the frequency 500 H z , 18 of the 25 meas-

u red subjects belong to the same group, that a t 250 Hz, and for the f r e -

quencies 1 kHz and 2 kHz four of the six measured subjects belong to

the same group.

Table 11-D-111. Number of subjects in the different DI groups. (@ means not tested. )

f = 1 kHz

A s can be seen in Table 11-D-I11 many of the subjects have different

types of DI fo r different frequencies.

Five subjects have been tested a t the age of about 10 yea r s and have

been retested a t the age of about 17 years . F o r four subjects we have I

got a decrease of DI, but not in a l l ca ses a s much a s expected by per - I ceptual maturation. Fig. 11-D-6 shows DI for f = 1 kHz for one subject

a t different ages. I 3 . 6.4 Conclusions f rom the DI measurements I

One of the important resul ts of our experiments i s the documentation

of the change of the discrimination l imen and with this the improvement

of discrimination ability with age. I t could not be proved that auditory I

training has a big o r any importance a t a l l for the change of discrimina-

tion l imen for hearing-impaired children. Because of perceptual matura-

tion discrimination ability improves and auditory training should be in-

tensified for hearing-impaired children age 13-14 yea r s and above.

Another of our goals in this experiment was to find a tes t for the diag-

nosis of total deafness. The DI t e s t i s not useful for diagnosis because

there i s no significant difference between tactual and auditive DI. But

the tes t can yield information on perceptual d i so rde r s (Group c).

SIGNAL DURATION (T) msec.

0-4 AGE 11.2 YEARS

X.-X AGE 16.8 YEARS

125 500 2000 FREQUENCY Hz

Fig. 11-D-6. Intensity discr iminat ion l imen as a function of signal duration for a hear ing- impaired subject measured a t different ages .

STL-QPSR 213/1974 81.

I

Increased sensitivity for intensity variations could be observed in the

DI test for some subjects for the whole frequency range o r a part of it.

To increase the exploitation of residual hearing, hearing aids with com-

pression could be used, and especially hearing aids with frequency

selective compression.

The training of the perception of loudness differences with hearing- I

I impaired children i s one of the basic parts in auditory training both for

general sound perception and speech prosody perception. The pedagogical

conclusions from the DI test are: in auditory training a t an early age,

the teacher has to be very careful in loudness discrimination training not

to use signals which a r e too short and not to use intensity differences

which a r e too small. Intensity variations in the ea r of the hearing-im- I paired child after the peak clipping and distortion of the hearing aid have

to be sufficiently large. The teacher has to be aware of the possibilities

that the child' s performance in different frequency ranges can be dif-

ferent. 1

4. F i r s t formant-frequency discrimination

4. 1 Introduction ---------- Many severely hearing-impaired subjects have sloping audiograms ,

and a very severe hearing loss o r no response for frequencies above

1 kHz. If the hearing loss i s of the type C . . . i t i s not clear whether

the threshold in the low-frequency range i s a hearing o r a vibration

threshold. Only some discrimination measurements can give an answer

to this problem. The purpose of these experiments was to measure the

discrimination ability in the frequency range below 1 kHz and to diagnose

total deafness and vowel discrimination ability. I

To investigate the discrimination ability a t the frequency range 200- 1 I

1000 Hz we measured the F discrimination limen in steady- state vowels. 1 In a previous experiment by Pickett and M&rtony (1970) six subjects with

hearing losses between 75 and 102 dB,, aged about 20 years , were tested.

The mean value for al l the subjects and al l the measured formant fre-

quencies was about b F1/FI = 6 % (one-formant vowels). In the recent

experiment we used a slightly different experimental method but the im-

portant difference was in the hearing loss and age of the subject.

FREQUENCY kHz

4 Y c. Y n *

'r= 700 msec t '=300mw T=700 msec

Fig. 11-D-7. Spectrum and time function of stimuli in D F t e s t s . 1

STIMULI COMBINATION

1

'5 F,

F,+AF,

F,+AF.,

2

F, F,+Af;

F.

F,+AF,

same

diff

diff

same i

After DF1 for a given F1 has been reached the entire measuring

procedure was repeated with different Fl. The measurements s tar ted

with Fi = 224 Hz and continued with an increasing Fl.

At training and testing a teaching machine was used (TTT2, Spens & Ris-

berg 1968). Earphones used in the test were of type TDH 39 with cushion

M X - ~ I / A R . The subjects had to p ress buttons for answering "samet ' o r

"different", a light indicated correc t o r incorrect answers. There was

no time l imit for answering. On a counter the number of total and cor-

r ec t answers could be read out. The stimuli could not be repeated.

The introduction was given orally and with sign language, for some

younger subjects extra introduction was given by the use of pictures

where the stimuli were represented by b a r s of different colors. I

4 ._4 -subj 5cLs- - Three groups of subjects have been tested.

4.4. 1 Tes t group

The subjects in the tes t group were 16 profoundly hearing-impaired

(HI) school children, aged 10-15 years . The subjects' hearing loeses

varied between 91 and > 117 dB (they had audiograms of the types m

C4, C5, and C6 with about equal distribution). All subjects had pre-

lingual hearing lo s s e s and were well trained in participating in psycho-

acoustic tests . Six of the subjects were tested twice, f i r s t a t the age

of 10-11 yea r s and later a t the age of 14-15 years .

4 .4 .2 Control group 1

Three normal-hearing children, age 10- 12 years , served a s con- I I

t ro l group 1. Six normal-hearing adults served a s control group 2.

Two of the adults have even been tested with tactual stimulation using

a bone conductor of type Danavox D (120 ohm). The vibrator was held , between the thumb and the forefinger. Noise masking was used to avoid

auditory perception.

4. 5 Results ------- 4. 5. 1 Normal-hearing subjects

The resul ts a r e shown in Fig. 11-D-8. F o r auditive perception the

resul ts a r e nearly frequency independent. The discrimination limen

STL-QPSR 2- 3/1974 84.

I3F1/F1 fo r adults i s about 3 % and fo r children about 15 %. D F ~ / F ~

measu red with tactual stimulation i s about 20 70 f o r F 400 Hz, 1 h a s a lower value f o r F 317 Hz, and a value higher than 42 70 fo r 1 = F1 = 224 Hz. The change of Fl i s received a t tactual stimulation

only a s a loudness change. Our data a r e about the s a m e a s those

measured by Flanagan (1955).

FIRST FORMANT FREQUENCY (5 ) Hz

Fig. 11-D-8. F i r s t fo rmant frequency discrimination l imen a s a function of F1 fo r normal-hear ing subjects. .

4. 5.2 D F ~ / F ~ for younger HI subjects

Complete resu l t s could not be obtained a t a l l f requencies fo r any

of the subjects. One subject had no positive resu l t f o r any measured

F1, four subjects could discr iminate differences of 42 70 for

Fi 300-400 H z ( s ee Fig. 11-D- 10). Very long training t ime

was neces sa ry to obtain the f i r s t D F value; a t continued measu re - 1 men t s a t different F shor te r training was sufficient. Fig. 11-D-9 1 shows the learning curve f o r one subject f o r F - 214 Hz and Fl =

1 - 317 Hz. If the subject had 75 '$0 c o r r e c t answer s a l i s t with lower

o L ' I I I t I I I

200 400 600 800 FIRST FORMANT FREQUENCY, (F1) HZ

SUBJ: TH

0---O AGE 14.0 YEARS

- n-x AGE 10.8 YEARS

125 ' 500 2000 FREQUENCY Hz

Fig. 11-D-10. First formant-frequency discrimination limen for a hearing-impaired subject measured at different ages . -

STL-QPSR 2-3/1974

p Fl was chosen, with less than 75 % correct answer s a l i s t with

the s a m e o r l a r g e r h F i was tested.

4.5. 3 D F ~ / F ~ change with age

Different discrimination l imen fo r different ages could be ob-

se rved for normal-hear ing and hearing-impaired subjects. Fig.

11-D-10 shows D F ~ / F ~ for one subject and Fig. 11-D-I 1 shows the

change of mean value of D F ~ / F ~ (frequencies F1 = 214 H z , 448 Hz,

and 897 Hz) for all subjects. F o r the f requencies where no D F i

could be measu red D F ~ / F ~ = 50 % has been taken a t the calculation

of the mean value and a special symbol ( > ) has been used in the

figure. The data fo r normal-hear ing subjects a r e the resu l t s for

the control groups i and 2.

0 m-tr 14-15

AGE YEARS

Fi = 224 Hz, 448-HZ, 897 Hz.

0 DF1 obtained fo r all f re - quencies.

DF l not obtained for a l l frequencies.

a Normal-hear ing subjects.

4. 5.4 D F ~ / F ~ for older HI subjects

The measur ing of D F for older subjects needs much sho r t e r 1 t raining and testing t ime compared with the younger ones. The re

i s a c l ea r difference i n the r e su l t s between the subjects with audio-

gram types C4 and C6. Subjects with audiogram type C5 show grea t

variat ions. Fig. 11-D-12 shows D F ~ / F ~ a s a function of Ft for sub-

jects with different audiogram types. All l imen curves show a min-

imum a t F1 = 300-400 Hz.

' Fig. 11-D- 12. Mean value and variation of D F ~ / F ~ for subjects with t h e same type of audiograms. Age: > 14 years.

- -

45

40

* 35-

30- s L-25- \

20-

15

10

5

I I I I I I I I +

- c4 N=6

\ \ \ \

- \ 1 \ p----- - -------

LA - \ /

- - - \ /------

L ---------

4 5 . 1 1 I 1 I I I I t I I I I I * \

45. , w

---,-,,,,,,---- -.-/c~

40 - c5 40 - C6 35 - 30 -

z= Y Z 5 -

?:?: 40. -

10 - -

5 - \ - 5 - L--J

O200 ' I 1 , 1 1 1

400 600 I 1 1 1 I

800 O & 1 , t I I I I 1 _

400 600 800 O*& 400 600 800 FIRST FORMANT FREQUENCY, (F1)Hz FIRST FORMANT FREQUENCV, (F1) HZ FIRST FORMANT FREQUENCV, (6) HZ

STL-QPSR 2-3/1974

Fig. 1I.D-13 ihows the mean value of D F ~ / F ~ a s a function of hearing

loss . The mean value i s calculated f rom the bFI a t the three Fi values:

Fi = 224 Hz , 448 Hz, and 897 Hz* (There 3s only a slight difference be-

tween this calculation and when calculating f t o m DFl a t a l l the five Fi values. )

In the P i c k e t t - ~ h r t o n y (1970) tes t college students with a hearing los s

below 102 dBm were tested. The experimental technique was somewhat

different than our s but the resu l t s can be compared.

The resu l t s in the two t e s t s show that for audiograms better than C4

(usually a l e s s hearing loss than 90-95 dB) the D F ~ / F ~ is for the few

measured subjects only slightly higher than for normal-hearing subjects.

F o r subjects with a hearing loss between 90 dBm and about 100 dBm

( "J C4) the measured D F ~ / F ~ i s higher but below the value for tactual

stimulation. F o r a hearing loss higher than 100 dBm-105 dB ( R/ C6) m a l l the measured l imens a r e of the same amount o r higher than for tactual

stimulation. F o r hearing losses of type C5, D F ~ / ~ between about 10 % and 40 70 could be measured (for one case a t Pickett-Mhrtony evenlower).

4. 6 Conclusion --------- The F discrimination tes t shows a clear difference in discrimination 1

ability for subjects with a hearing loss below 90-95 dBm and higher than

100-105 dBm. The f i r s t group has values only somewhat higher than nor-

m a l which indicates residual hearing with acceptable discrimination abi-

lity. Subjects with a hearing los s higher than 100-105 dBm show high I

D F ~ / F ' ~ which indicates that they have no residual hearing o r severe per-

ceptual difficulties. F o r subjects with a hearing los s inbetween these

two groups (C4 and part ly C5) there i s a la rge variation in D F ~ / F ~ . i ~ Some of the subjects have certainly a residual hearing and r a the r accep-

table discrimination ability ( ~ 4 ) , for other subjects there i s doubtful 1 whether they have residual hearing (C4, C 5). anyhow, their discrimina-

tion ability i s poor and for the r e s t , there i s no residual hearing and no

discriminability (C5).

The test indicates clearly total deafness but because of the long

training t ime, especially for the younger subjects, i t has only limited

practical value.

STL-QPSR 2-3/1974 87.

A s in the DI t e s t even he re a change of discrimination l imen with age

could be observed. This indicates that auditory training of hearing im-

paired children a t the age 14 yea r s and higher should not be neglected, I

on the contrary, i t should be intensified. If the D F ~ / F ~ for a person is

m o r e than 20 70 this subject can discriminate only th ree o r l e s s numbers

of different vowel groups by F1 in tes t conditions like ours - in conti-

nuous speech - and with different ta lkers i t i s doubtful if even theore-

tically any vowel identification i s possible. In- such a case it i s maybe

a waste of t ime to t ra in vowel discrimination. If D F ~ / F ~ i s 15 % o r l e s s ,

systematic auditory training of vowel discrimination is important and can 1

resu l t in vowel perception in continuous speech. I 5. Summary I

The most important finding in these two tes t s i s the documentation 1 of the changing of discrimination l imen with the age. The DF1 measure-

ments indicate total deafness but because of their long training and test-

ing t ime these measurements a r e not practically useful. Discrimina-

tion l imens, especially for subjects with audiogram type C4 and C5, show

great variations. Many of the subjects showed a t stimulation in the e a r

discrimination l imens which a r e higher than tactual stimulation in the I

hand for normal-hearing adults. 1 References:

BOOTHROYD, A. (1972): "Sensory a ids r e sea rch project - Clarke School for the Deaf", pp. 367-377 in Speech Communication Ability and Profound Deafness (ed. G. Fant), A . G. Bell Ass . , Washington, D. C.

DANAHER, E. M. , OSBERGER, M. J. , and PICKETT, J. M. (1973): "Dis- crimination of formant frequency transit ions in synthetic vowels", J .S .H.R. 1 6 , pp. 439-451. -

DANAHER, E. M. and PICKETT, J. M. (1974): "Temporal masking in sensorineural subjects and i t s effect on syllable discrimination", to be publ. in the Proc. of the Speech Communication Seminar, Stockholm 1974, Vol. 4, pp. 63-68. I

DENES, P. and NAUNTON, R. F. (1950): "The clinical detection of audi- tory recruitment", J. Laryngol. and Otol. 64, pp. 375-398. -

DiCARLO, L. (1962): "Some relationships between frequency discrimina- tion and speech reception performance", J .Aud.Res. 2, pp. 37-49. -

FANT, G. (1959): "Acoustic analysis and synthesis of speech with applica- tions to Swedish", Er icsson Technics, No. 1 , pp. 3-108.

FLANAGAN, J. L. (1955): "A difference l imen for vowel formant f r e - quency", J.Acoust.Soc.Am. 27, pp. 613-617. -

STL-QPSR 2-3/1974 88.

GABRIELSSON, A. , JOHANSSON, B. , LINDBLAD, A-C. , PERSSON, L. , PETTERSSON, A. , and ROSENQVIST, B. (forthcoming): "Fre- quency discrimination for bands of noise", in Audiology 14, pp. 1-20.

GENGEL, R. W. (1969): "Pract ice effects in frequency discrimination by hearing impaired children", J. S. H.R. c, pp. 847-856. I

JERGER, J. , LASSMAN SHEDD, J . , and HARFORD, E. (1959): "On the detection of extremely small changes in sound intensity", AMA Arch. of Otolaryngology 6q, pp. 200-2 11.

JOHANSSON, B. (1961): "A new coding amplifier system for the severely hard of hearing", pp. 655-657 in Proc . of the IIIrd ICA Stutteart 1959, Vol. I1 (ed. L . Cremer ) , E lsevier , Amsterdam.

LEI-IISTE, I . (1970): Suprasegmentals , The M. I. T . P r e s s , Cambridge, Mass.

L ~ S C H E R , E . (1951): "The difference l imen of intensity variations of pure tones and i t s diagnostic significance", J. Laryngol . OtoL - 65, 486-510.

MARTIN, E. S. , PICKETT, J. M. , and COLTEN, S. (1972): "Discrimina- tion of vowel formant transit ions bv l i s teners with severe sensori- neural hearing loss", pp. 81-98 in Speech Communication Ability and Profound Deafness (ed. G. Fant) , A. G. Bell A s s . , Washing- ton, D.C.

MARTONY, 3'. (1974): "Change of intensity discrimination l imen in children", Acustica 31, - Dec. issue.

MAZEAS, R. (1968): "Hearing capacity, i t s measurement and calcula- tion", Am. Annals of the Deaf 113, pp. 268-274. -

MAZEAS, R. (1972): "Auditory capacity and hearing aids", p . 99-106 in Speech Communication ~ b i l i t ~ and ~ r o f o u n d b e a f n e s s -(ed. G. Fant) , A. G. Bell Ass . , Washington, D. C.

NOBER, E . H. (1967): "Vibrotactile sensitivity of deaf children to high intensity soundr', The Laryngoscope - 78, pp. 2 128 -2 146. I

NOBER, E . H. (1970): "Cutile a i r and bone conduction thresholds of the deaf", Exceptional Children 36, pp. 571 -579. -

PICKETT, J. M. (1963): "Tactual communication of speech sounds to the deaf: Comparison with lipreading", J. S.H. D. 28, pp. 315-33 . -

PICKETT, J. M. , DALY, R. L. , and BRAND, S. L. (1965): "Discrimina- tion of spectral cut-off frequency in residual hearing and in normal hearing", paper B33 presented a t the 5th ICA, ~ i & g e .

I I

PICKETT, J. M. and MARTIN, E . S. (1968): "Some comparative meas - urements of impaired discrimination for sound spectral differences", Am. Annals of the Deaf 113,' pp. 259-267. -

PICKETT, J. M. and M ~ R T O N Y , J. (1970): "Low-frequency vowel for- mant discrimination in hearing-impaired l is teners" , J. S. H. R. 13, - pp. 347-359.

PIMONOW, L. (1968): "Technical and physiological problems in the ap- lication of synthetic speech to au ra l rehabilitation", Am. Annals of the Deaf 113, pp. 275-282. -

RISBERG, A. (1968): "Periodic-nonperiodic tes t of hearing capacity1' STL-QPSR 2-3/1968, pp. 19-28.

i

STL-QPSR 2-3/1974 89.

I

RISBERG , A. (1974): tlDitignas a v total diSvhet", paper given a t Nordisk Kurs i Atidiologi (~can'dinavian Course in Audiology), Trondheim.

RISBERG, A. , GALYAS, K. , and FRANZ~N, 0, (1965): "Phonemic identification with lip- readin alone and lipreading supplemented by residual hearing o r tactua! communicatibh"~ GTL-QPSR 1/1965, pp. 14-21.

RISBERG, A. and MHRTONY, J. (1972): "A method for the clas sificaf- tion of audiograms", pp. 135- 139 in Speech Communication Ability and Profound Deafness (ed. G. ant), A. G. Bell Ass . , Washing- ton, D.C. 1

I t I RUSLER, G. (1957): "Uber die Vibrationsempfindung", Z. f. exp. angew.

Psychol. 4, pp. 549-602.

SIEGENTHALER, B. M. (1969): "Maturation of auditory abili t ies in childrent ' , Int. Audiology - 8 , pp. 59-71. 1

SODERQVIST, D. R . and MOORE, M. J. (1970): "Effect of training on frequency discrimination in pr imary school children", J. of Aud. Res. 10, pp. 185-192. -

SPENS, K-E. and RISBERG, A. (1968): "TTT Machine for group exper- imentation", STL-QPSR 2-3/1968, pp. 16- 18.

SVENSSON, S-G. (1974): "Prosody and g rammar in speech perception", Monograph 2, Institute of Linguistics, Stockholm University, Diss. ~ I