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-