TREATMENT OF THE DEAF

Hearing Aids and their Modern Conception *

By G. EWART MARTIN, F.R.C.S.Ed.

Types of Deafness.?In discussing the problem of deafness we must

distinguish at the outset between the so-called " hard of hearing who tend to conceal their deafness, in fact who claim they are not

deaf, and the " actual deaf" who have no sense of hearing. These

latter may be congenitally deaf or have lost their hearing before the/

acquired speech and in the old terminology were called " deaf an

dumb." Also in this group of the "actual deaf" are those

have lost their hearing in later life through accident or disease who have retained their power of speech. The term

" deaf an

dumb "

is of course an entirely obsolete one because by model"11 educative measures deaf-mutes can be taught to speak. Those

have lost their hearing entirely by accident or disease can be traine also by educational methods to maintain their proper place in society- ^

In this discussion, however, we are concerned with the " hard 0

hearing." It is not possible to group these cases. They can be

slightly hard of hearing, moderately deaf, markedly deaf, extreme y

deaf, in fact going on to almost total deafness when presumably the^ would come under the second group.

The terms are admittedly confusing and they are made worse W

the fact that the patient conceals the deafness and never wants to told he is deaf.

History of Deafness.?Chronologically the history of

offers many interesting features. They are mostly concerned ^ the totally deaf. In the present day the deaf child must be consider^ not only as a clinical entity but as a vital factor in the econormcS ,

any country, while in the days of Aristotle the deaf and dumb ctl

was considered of less use than an animal and was destroyed. Ju-

lias been written and much tried by the old philosophers to educ these people, but little mention was ever made of the hard of heari

?possibly they managed to conceal their deafness. The first hear1

device does not appear in literature until about the seventeenth cent

when Ellipsis Otica was described for amplifying sounds. ^e

The problem is more acute to-day and the hard of hearing

admitting they are deaf and are seeking advice. ^ In the spring of 1939 I read a paper before the Society with

title " In Search of Hearing."

* Read at a meeting of the Edinburgh Medico-Chirurgical Society

5th June 1946. XS8

TREATMENT OF THE DEAF 159

The modern world relies more and more on the spoken voice rather an the printed word. This was emphasised over and over again Uring the war. The moral of the country would not have remained

So high if our leaders had communicated by pamphlets or the press lnstead of coming to the microphone and talking to the nation.

Therefore during the last six years the public have been dependent n the wireless. Unfortunately very few new wireless sets were

^able. Repairs have been impossible and many people have had

to 1Sten t0 ^^stort:e^ reproduction, and this was quite unintelligible

People over the sixties who were showing early signs of senile nerve ness- Consequently they began to seek advice. As a result of the war with its nervous tension, its rationing and its

?ut, senile nerve deafness has begun to show earlier than in the Past.

&

Recent research has shown that unfortunately deafness as a whole ?n the upgrade. (This includes middle-ear deafness as well as

Perceptiye deafness.) ^i

Otitis Media.?Recent investigation into the case records of ear

shQease *n the Department of the Royal Infirmary under my charge been

S*nce use sulphonamides, cases of otitis media have en

re^uced to almost half. At its face value this was extremely act raging' but the mastoid and intracranial complications had

y ^creased showing that the percentage of complications has

caSes rnore than doubled. On further investigation into individual We were appalled by the amount of deafness. The acute ear

nia ?Se ltS symPtoms with the use of sulphonamide, but in a great

behi H?aSeS results of the acute infection remain, fluid forming

rema' ^rum ^oes not absorb, adhesions form and the patient

^Pro18 <^ea*"?E deafness wbich, in the majority of cases, cannot be

^n^rri^ar investigations in other hospitals have corroborated these

in There has, therefore, been a larger percentage of deafness

J?ls ^nedia in recent years, C0 e. lca,l Research Council Committees.?The Medical Research

sw-C have appointed a committee to enquire into the medical and

fin(j.ICa* treatment of the deaf. This committee has not finished its

in So that little can be said about the methods to be adopted otitis

e^?rt to Prevent deafness of this type. Many consider that

^niedia should be a notifiable disease. ^

e Medical Research Council also appointed a second committee the de .?"acoustics. This committee has finished its deliberations on

Used ?Slgn' Performance and application of electro-acoustic equipment sUch f1 *nvestigation and alleviation of deafness and has initiated

c?nn<? mental. investigations as it considered necessary in such ection. The r

We c eport of the committee is in the hands of the publishers and

not so far discuss it but we know that an efficient hearing aid

160 G. EWART MARTIN

has been devised adopting a circuit much more simple than previously used by the makers of reputable hearing aids.

This instrument is comparatively cheap to manufacture but no

measures have been taken yet for its production and supply. It has been recommended that arrangements might be made

through the Ministry of Supply for the mass production of this hearing aid by the present hearing aid manufacturers and that the aids should be dispensed through special clinics attached to the otological climcS of the larger hospitals.

Unfortunately news of this instrument has been published, even in Parliament, before any action has been taken as regards its production or prescription.

However efficient this hearing aid may be it is by no means the

complete answer to the problem of deafness. No hearing aid carl

be universal. Its type should depend on the character of the patient s

deafness.

In the past the public have been scandalously misled by advertise ments for hearing aids. Even stamp books supplied by the P?s^ Office had glowing advertisements of " deaf ears hear again- Naturally deaf people answered these advertisements and were hande^ hearing aids across the counter?hearing aids of use in a very sma

percentage of early middle-ear deafness but detrimental to a perceptlVe deafness.

We otologists were definitely to blame for not preventing tn

exploitation of the deaf by firms manufacturing these instrument5' The prescription of hearing aids was not considered the duty of

the

otologists who were concerned with disease of the ear, not its diminishing function. Only a few otologists were interested in acoustics.

The subject of hearing aids was little ventilated until twelve yea*

ago and we are indebted to Cleminson, Terence Cawthorne and Pny^ Kerridge for much of the early work on hearing aids. In 1937, u

the auspices of the late Dr Kerridge, a clinic was instituted in Universi y

College Hospital, London, for giving advice on hearing problert^j It provided a centre for investigation and for demonstrations to medica students, doctors and teachers of the deaf. It did much to re

M the price of the advertised mass produced hearing aids and it br0 to the minds of the otologists the fact that many firms interested

1

radio and acoustics were experimenting on the making of valve ai ^ The only form of reimbursement these firms had for their experiment3 work was an added cost to the price of the instrument so evolved. ^

Attempts were made to start a hearing aid clinic in Edinbu^ but these fell through owing to the fact that the makers of hearing a^g could not service them in Edinburgh nor could they have representati on the spot. One or two well-known hearing aid manufactur

opened agencies in Edinburgh. t

We felt that a hearing aid clinic outside an ear, nose and thr^ department was not actually scientific. It might lead to hear1

TREATMENT OF THE DEAF 161

aids being prescribed for patients whose ear condition really precluded j*Se an aid, such as a perceptive deafness with a very low upper ^e limit or a perceptive deafness accompanying a disseminated

Xerosis.

Types of Hearing Aids

of ^ menti?ned in my last communication there are two main types

earing aids, (i) non-electrical (2) electrical.

k Non-electrical hearing aids (apart from minor alterations) have

Gen Used for the last one hundred years. These hearing aids are Popular because of their conspicuousness, but still they are the

bearing aids which should be used in certain types of deafness, and ̂

rinc^Pa^ types include the various forms of resonators, ear trumpets sPeaking tubes. They are merely conductors of sound and not

dist 6rS' whereby the natural voice is well reproduced without

.0rtl?n. The banjo ear trumpet is possibly the best of this type

PubrStrUment* ^ Can k0 Pro(^uce<^ cheaply but, unfortunately, the ,,

lc have never forgotten Punch's well-known suffragette cartoon

toaye to?t and y're oot " so this is an instrument which no one likes

avi^r?^Uce *n Public. In an effort to make these aids less conspicuous,

^ej^c es have been constructed with small flattened ear trumpets

Th ^ a kanc*to the head with the sound conductors pointing forwards,

la^CSe are almost too directional and not nearly so proficient as the type of ear trumpet.

car 6 ?^est form of non-electrical hearing aid is the one we all

the ^ ah?ut with us and which can be noticed in use by nearly half

Cll au^ence at any meeting?that is the hand placed behind the ear, Pe to direct the sound towards the ear.

0f ̂ 6 Physiological change of old age in the cochlea gives a lowering

Ther tone limit making it difficult to pick up the finer sounds.

s?Und ^ a^S? a centra^ change which results in a difficulty in separating

an ,S" ^ child can comfortably separate out three groups of sounds, an : J!.1"' as we all know, can converse with one person and yet have c0rtles

ln?> into the general conversation of the room. However there

conv a ^me when sounds cannot be separated and though a tete-a-tete

a nofse1a^0n can he heard in a quiet room nothing can be heard in are t f/. The individual cannot keep up a conversation if two people Ho f ln? at the same time. Where the sounds cannot be separated

hear(i m

amphfication will allow the general conversation to be as s

as the electrical aid amplifies the surrounding noise as well

Va^ * AU that is required is something to direct the sound

^recti S

Gar an<^ cut out ?ther noise. This can be done with a

th?na^-resonator or in the more advanced cases a speaking tube; cOnver G-1S no reason why such a deaf person should not carry on a bu22 10n with his neighbour using a speaking tube during the

^?uld ^eneral conversation, whereas without the speaking tube he

Vr>T ?n ̂ hear the buzz and not the conversation. Unfortunately 0I" LIV' NO. 3

162 G. EWART MARTIN

this type of patient tries to conceal his deafness and in a noisy room

edges close up to the person he is conversing with who has to raise his voice to an unnatural pitch?an embarrassing situation if there Is

a sudden pause in the general conversation. Electrical Hearing Aids.?I. The micro-telephone; this is simply

a microphone constructed of rough carbon granules energised by a

battery and with a small ear-piece. Actually the microphone can be doubled or trebled to get larger amplification and instead of the

ear-piece worn over or fitted into the ear a bone conductor held ?n

the mastoid process can be used.

This type of micro-telephone gives a 16 decibel amplification only and is usually noisy, at least the machine manufactured instrument must necessarily be. It is essentially wearable. In the past it was

the only known electrical instrument, and unfortunately laid itse

open to mass production. It is of use in the very mild cases of mid^e ear deafness or in an early otosclerosis?patients who usually heaf

better in a noise. It proved a definite aid until the otoscleroti0 developed a nerve involvement as well when the instrument was

danger. It is definitely detrimental to the perceptive deafness. ,

This type of instrument could be made at very small cost. I

a hand-made instrument constructed for use in the consulting-r??fj at the cost of 17s. 6d. This was a copy of an instrument which

so

for seventeen guineas?not a bad profit. However, considering ^ ,

the firms were spending ,?600 a week on advertisements there na

to be a profit somewhere. The difficulty arose in that these instrument were handed across the counter?some firms pretended to do a hearing test as a bait. The deaf person wishing to get in touch with t^e

outside world fell, and came later to the otologist with the tale of

that he just could not hear with or without the instrument. *?

otologist could give little help. At present the hand-made n^i^0

telephone with special microphone and bone conductor gives ve

good results in picked cases of early middle-ear deafness where wearable aid is essential.

^ 2. The valve amplifier. These aids have developed along

the development of radio. Originally they were clumsy, unweara and scarcely portable because of the necessity of the heavy high tens

battery and the large low tension battery or accumulator. Before the war very small radio valves were employed and batte^ ^

were slightly less in size. One or two firms had actually produce wearable valve aid but the batteries were still rather clumsy and he ^ to carry. However, the patient could wear the aid with a certain am?u

of inconvenience. a

The war has changed all this. The army had to use radio aS

means of communication, small radio sets had to be fitted into taf|eSt they had to be carried and they had to be flown. The rnin^ (r)i instruments were sent up in balloons for experimental work at t

altitudes. The instruments had to be made smaller and yet efficie

TREATMENT OF THE DEAF 163

^hich required a lot of experimental work and no individual firm 11 d have financed this work. However, the makers of these struments are reaping now the benefit of the experiments. The

tj^10 valves are almost the size of a pea, the transformers not bigger ar^n t^le thumb nail, the microphone almost the size of a shirt button,

> most important, the batteries can be constructed no bigger than

^^tchbox and yet give a 50 volt potential for a longer period than fleed?^ Curn^ersome high tension battery. The low tension battery

that ?n^ 1 tC> vo^ts to ^eat sma^ Pea valve. All this means

toat *he valve aid can be made wearable. These wearable aids are a Certain extent flimsy and are of little use to the manual worker cept as an occasional aid.

nce again it must be emphasised that no hearing aid is universal,

that Pr*ce ?f these aids is still a consideration. It has been estimated

at the circuit devised by the Medical Research Council could be for about ? 8, possibly less to hospital patients.

e reason for the extra cost of instruments made by reliable

befQU acturers is that they have to allow patients a trial of the machine for

6 ^Urc^ase- With an electrical hearing aid this trial is necessary

tirtie01^6 Pat*ents especially those who have been deaf for a long ajj

' ln fact some patients can never get accustomed to a hearing ? ecause it amplifies all sounds and therefore makes hearing

ortable to a oerson who has? been shut out from noise for a

because W 0rn^0rtable to a person who has been shut out from noise for a ?nS Period.

C0 eafness Clinic.?Under the auspices of the Medical Research

L0nrj 1 a deafness Clinic was instituted in Queen Square Hospital,

aids a This clinic was really a research centre for electrical hearing

This h ^ wor"k was done there and useful information obtained.

d0n . eatness clinic might be taken as an example of what must be

j^n every centre. the

n ^uture it must be the duty of the Otological Departments of

ear i^ntra^ hospitals in each region not only to treat diseases of the W?uidU, a^so to aid its diminishing function. These departments

(l) t Ve *n feet a tripartite duty. They would be concerned with

expect ment ?f diseases of the ear, (2) treatment of deafness by

of theant measures such as removal of any septic foci ; improvement

feriest afra*'on ?f the middle ear ; or by direct operation such as

(3) .

10n ^ the results of this operation warrant its continuance; ?n the ^ ac*v*ce on the use of a suitable hearing aid and also advice

Wl^ Ucat*onal and sociological training of the deaf. legated6 k?sP*tals are *n cl?se proximity this third role might be for a(jv.

to a single deafness clinic where patients could be referred ^he So ?ei?n.' anc* ^ necessary the fitting of, a suitable hearing aid. AdviCe

10 ?^ca^ aspect of this clinic would have to be emphasised.

^ployj^11^ Siyen on lip-reading and on the possibility of congenial

Se three duties overlap. Every case of otitis media coming

164 G. EWART MARTIN

to the Ear, Nose and Throat Department has the hearing tested*

every case of progressive middle-ear catarrh or otosclerosis has a iu

range of hearing charted along with an audiometric test. However a deafness clinic means more than this and we are hopin?

to have such a clinic functioning whenever material is available.

Testing for Hearing Aids

At the Deafness Clinic in Queen Square Hospital patients wh0

have had the ears examined, an audiometric test done, the type 0

^ deafness diagnosed, are tested with actual spoken words?groups

0

words have been chosen of single syllables without any correlation' These are transmitted to the patient by gramophone records throug an amplifier and loud speaker, but varying the amplification so tha the patient can be tested theoretically at different levels of speeC without altering the position. j

Ordinary speech in a quiet room reaches the human ear at a leV^ varying from 30 to 60 decibels making an average of 45 ^eC

at above the normal threshold, though it should be well understood a

15 decibels below this, although this depends on the surroundi11? noise. With normal hearing the voice is unconsciously raised about 10 to 25 decibels above the level of background noise. ^

decibel is the unit of intensity of sound, 10 decibels corresponding a tenfold increase in sound intensity, 20 decibels to a hundred*0 increase. A loud voice in a quiet room reaches the ear at abo

60 decibels amplification?that is about a millionfold increase in soUn

intensity.) A patient listens to and repeats the groups of words on the recof

but at different amplifications. The percentage of the hearing thus be charted and a graph obtained. It is curious that if sentefl

^ are used instead of single words it gives a remarkably different gra^ varying, of course, with the intelligibility of the patient. It lS

^ this reason that single words have been chosen for the test.

^ 40 per cent, level of word recognition was taken as a critical leV^ For instance, a person might have no difficulty with a loud converse ^

. ... nti& with the ordinary conversation voice. During the test the pa a

sits in front of the loud speaker with his ear against a frame (a^g given distance from the loud speaker?this distance of course

^ to be measured out by means of an artificial ear to get the

amplification readings). After the test the patient moves away ^ the loud speaker and is fitted with various types of hearing aids-"^e microphone of the hearing aid replacing the patient's ear in u

aperture in front of the loud speaker while the patient listens thr? ^

the ear-piece in comfort. The tests are repeated with, of course ̂ different series of words and a percentage recognition of the charted. The alteration in the graph can be seen easily and

TREATMENT OF THE DEAF 165

PfP*1 showing the nearest reading to the patient's original graph is a en as the most suitable hearing aid for the patient. One finds in

cases that the hearing aid does not improve the patient's hearing /nciently to hear at church level or the ordinary conversation voice, lle it is usual that the loud voice can be brought up. In such a

fSe no electrical hearing aid would be recommended because a non- c rical aid would be sufficient to allow the patient to hear a loud

aidVerSat*?n vo*ce Possibly with less distortion than the electrical

To allow a deaf person to hear in a theatre or at a concert a different

^ ?o !s advisable. An amplifier picks up all sounds and the closer

to l ?Un(^ *s to the microphone the louder that sound must appear

1 e deaf person. If a deaf person uses an ordinary amplifier in a

sn 1 ?r theatre with the intensity of amplification turned to the

k .er or orchestra with all other sounds cut out all would be well,

nojs ^ his next-door neighbour coughed or moved in his chair that would be so intensified by the amplification that it would cut out

0 ,

er sounds. Consequently it has been suggested that the hall

for Gatre *s with a microphone and an amplifier such as is used

e

a ^?UC* sPeaker, but the loud speaker is replaced by a wire which

the -S round the hall. A deaf person using his own aid but with

tilerirni.CroPh?ne removed and replaced by an induction coil would

^ Pick up what is being delivered to the microphone in the pulpit

sta?e without distortion of the surrounding sounds.

^ade11 research work has still to be done and little headway can be

f0 until further deafness clinics are established. The equipment

s^ch a clinic is rather difficult to obtain but we are hoping that the

^stry of Supply may help with this. c?uld K test*n? hearing is a wearisome business, but much of it

Mio 6 ^0ne by the technicians under the supervision of an otologist

decide whether the patient should be allowed to use a hearing instr- electrical type or whether he would benefit by a non-electrical

rument.

Nine Commandments for the Deaf

their rT ^ P^klic must be re-educated to be less self-conscious of

^ability and thereby not try to conceal their deafness. the "T1"^ Harvard Medical School gives nine commandments for

ard of hearing " which might be quoted :?

Thou shalt frankly confess thy deafness to thyself and before

j j thy fellow men. Let there be no deceit or false pride. ou shalt not covet thy neighbour's hearing, but shall rejoice that thou livest in an age when thy handicap can be made

jjj so small.

Early and again shalt thou consult thy otologist and accept every scientific aid he can render.

U UV" NO. 3

166 G. EWART MARTIN

IV. Eschew the quack and his devices. Easy and broad is

way to his door and many there be that find it.

V. Thou shalt join and work for a league for the hard of hearing where thou wilt receive encouragement and stimulation

f?r

thyself and wilt find happiness in serving thy brother. VI. So love thy neighbour that thou do everything in thy poWer

to help him when he would have speech with you. this end :

VII. Thou shalt study lip-reading in season and out of season. VIII. Thou shalt secure and use the best ear phone thou canst

discover.

IX. Triumphantly shalt thou rise above thy infirmity, and s?

conduct thy life that the world hath need of thee.

The Deaf Child

I have purposely refrained from talking about the problem of deaf child. I have tried to limit myself as much as possible to

t

deaf adult, but I must refer for a moment to the problem of *

education of the deaf which of course starts with the child.

A further committee of the Medical Research Council is discussin? this subject.

For the deaf-mute there must be only educative measures, teach#"5 of lip-reading to teach him to speak and communicate with other5 even in a toneless voice. For those with islands of hearing a certain amount of education can be obtained by the use of an amplifier an the hard of hearing can be taught to lip-read and to use, if necessary* an amplifier. Special classes can be fitted with a microphone, amplifier and multiple ear phones, and different circuits can be tapPe so as to give different degrees of amplification.

Visiting the clinic in Manchester under the Ewings makes one rea 1

how little we are doing in our centres. Finance has always been a difficulty. Those of us who ha

been experimenting with hearing aids have had to do so at our 0

expense. However these days are passing, clinics will be 0Penl^f I hope, everywhere so that the otologist can be blamed no longer not trying to treat the function of the ear, and patients will not

n

to be bullied by first class advertisements and first class showmen 1

buying instruments which will prove useless and even detrimental-