THE IMPORTANCE OF AUDITORY COMMUNICATION*BY

L. FISCHFrom the Audiology Unit, Institute ofLaryngology and Otology, London

(RECEIVED FOR PUBLICATION NOVEMBER 27, 1956)

Communication, that is transmission of informa-tion to the outside world and receiving informationfrom it, is a vital function of every single living unit.

In the simplest organism the information is alsoof a simple nature, for example, a chemical reaction,or a tactile sensation. In an organism of highercomplexity the information necessary for life willbe correspondingly more complicated.Human beings built for themselves a system of

symbols, a language, that helps them to transmitadequately the immense variety of information theyrequire. Sensations of sound were used as the basicmaterial for building this language. That is thechief reason why hearing, in other words 'auditorycommunication', is of supreme importance to man.

It was not by accident that, when it was necessaryto communicate information of great complexitywith great speed and economy, sound was used asthe most suitable medium available. There weregood physical and physiological reasons for it.The physical reason is the vibratory aspect of

sound in air and in the basilar membrane of theinner ear. Frequencies of vibration from 100 to10,000 cycles per second give a tremendous numberof possible combinations. The human ear candistinguish about 340,000 sounds of a certain pitchand loudness. These can be transmitted with speedand little effort. Above all, frequency analysis isthat outstanding characteristic of the auditoryapparatus which enables us to encode the greatvariety of information in this type of communica-tion. Other sensations also involve analysis on afrequency basis but only in hearing is it the funda-mental operation upon which everything else isoverlaid.The vibratory (physical) aspect of sound is, how-

ever, only part of what makes up the complexsensations resulting from it. This becomes clearwhen the most important of all sounds are con-sidered-that is speech.The acoustic wave forms of speech can be* A lecture given at the Institute of Child Health, Guy's Hospital,

London, in May, 1956.

measured and analysed in great detail. Variouselements of the complex wave form can be studied,and it can be determined which of these elementsare most vital for the transmission of the informa-tion. It is possible to reduce the highly complexwave form of speech to an infinitely clipped version,yet the speech remains intelligible (Licklider, 1950),and the critical information of the message is stilltransmitted adequately. It means that the informa-tion-bearing elements of speech sound can be, so tosay, extracted from the complex acoustic wave formof natural speech. In other words, natural speechhas a great redundancy. The brain is adapted toexploit this great redundancy of natural speech tomaintain communication under adverse conditions,which usually occur in the form of ever-presentsurrounding noise. This is one of the importantreasons why this type of communication is soefficient, and one of the biophysical reasons for theefficiency and superiority of auditory communica-tion by speech.We must mention another important reason.

Communication of language means transmission ofthoughts from brain to brain. Each thought maybe broken down into images. Each image corre-sponds to one word and to one individual visualpicture. According to the experimental phoneticianseach spoken word may be broken down-on theaverage-into four elementary sounds, calledphonetic elements or phonemes (Dreyfus-Graf,1950). Western European languages allow forarticulation, on the average, of a maximum of12 such phonetic elements per second. It meansthat three words can be communicated from brainto brain per second. Individual perception ofpictures begins to become confused when the speedexceeds more than three words. This is nearly thespeed of thinking. The rhythm of 12 elementarysounds (phonemes) per second allows the spokenlanguage to follow nearly the speed of thinking.Auditory communication is then the best available,most efficient and economic method of communicat-ing language from brain to brain. It has taken a

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long time for mankind to develop it. The primaryfunction of the larynx, phylogenetically, is not toproduce sound, but to prevent foreign bodies fromentering the respiratory tract. Production of speechsounds, and consequently oral language, is, so tosay, an artificial addition. It must have taken longin the history of man to develop the fine neuro-muscular coordination necessary for the voluntarymovements which produce speech sounds, andhearing is the most important feedback control ofthis neuromuscular mechanism. If hearing isabsent from birth or early childhood, and if a childremains untaught, from many aspects he stops at astage of development comparable to that of theearliest pre-historic stage of man.

If we do not want to leave such a child stuck atthat primitive stage, we must give him a language,and preferably teach him in such a way that heshould be able to communicate that languageorally, by speech. But not only because this is themost efficient method of communication. There isan additional and most important reason. Weknow that we cannot make out of a profoundly deafindividual a normal person. Our aim should be tomake him into a person who is able to communicatein the normal hearing society with a reasonabledegree of efficiency, and is reasonably adjusted tohis disability without segregating him for ever. Itmeans that we must help him to achieve indepen-dence in communication in the hearing society.And the greatest degree of independence in com-munication in a hearing society is communicationorally, by speech.

It is almost a truism to say that early detectionof impaired hearing will influence greatly the successof rehabilitation as defined above. Early detectionof deafness is of prime importance for severalreasons. If the deaf child is to be expected tocommunicate with reasonable success in a hearingsociety, he needs to be exposed to a normal speechpattern. This exposure produces the maximumresults when it is begun as early as possible in thechild's life (Fry and Whetnall, 1954).

Another reason for early detection is the followingone: Apparently some important language patternsare set during the early years and probably much ofit before the child enters school. Further trainingexerts only a modifying influence. It is necessaryto fix these patterns for the deaf child as early aspossible, and before he starts his schooling. Stillanother reason is the enormity of the task for a deafperson to achieve independence in communicationin a hearing society. To illustrate the difficulty Iwill borrow an analogy from information theory.

Natural speech is transmitted over a communica-

tion channel of full capacity. As I mentionedpreviously much of this capacity is redundant.Shannon in his communication theory has shownthat perfect transmission is possible over a channelof minimum capacity, admitting no redundancy atall. The price is an elaborate terminal codingequipment. The same happens in communicationof a profoundly deaf person. For him, whenreceiving a signal, the rule of all or nothing applies.He has to communicate over a channel of minimumcapacity, without any redundancy, and our task isto provide him with a terminal coding equipment,that is, we must teach him the correct interpretationof the signals which come to him over a com-munication channel of minimum capacity, admittingno redundancy.

Early Detection of DeafnessWhat are the chances of early detection of deaf-

ness? Naturally, it is easier to detect an almosttotal or very severe loss of hearing than a partial,less severe one. This is recognized by most people,but the signs, symptoms and serious consequencesof partial deafness are less well known, althoughnumerically these cases are more important.A very severely deaf child will not react to every-

day sounds at all; his speech will not start todevelop; it will be soon noticed that there is some-thing wrong. It may occur to the parents that thechild is deaf.On the other hand, a child with, let us say,

considerable amount of hearing for lower notes butsevere impairment for the higher ones, will react toa variety of everyday sounds and he will start tospeak; in familiar circumstances he may hear andunderstand many words and sentences (possiblywith the help of spontaneously acquired lip-reading).But when he has to learn a great number of newwords and hear them in unfamiliar circumstanceshe will fail and show various disorders. It may notoccur to the parents, or even to various educational,psychological and medical specialists that thetrouble is a serious hearing loss. This suggestionmay be encountered with scepticism. The childobviously can hear, therefore he cannot be deaf.The term 'deafness' is misleading. Usually it is

associated with the profound hearing loss whichused to be labelled by the now obsolete term 'deafand dumb'. The type of partial deafness, however,which I described, is very much more frequent. Itsserious symptoms are not always recognized.

Let us consider how language development isinfluenced in the deaf child.A normal child first develops some awareness of

happenings; he learns a few everyday situations and6

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the meaning of his experiences. It takes him eightor nine months to gain this inner language beforehe begins to use receptive language, that is beforehe begins to understand a few words spoken byothers (Myklebust, 1954). It takes him anotherfour or five months before he begins to use expressivelanguage and speak his first words. No child canlearn to speak unless he has learned to understandsome of what is said to him. The child understandsa limited vocabulary before he is able to use it as ameans of oral expression (Pratt, 1950).

This process of developing language in threesteps, inner, receptive, and finally expressivelanguage, will be modified in the deaf child accord-ing to the type of his hearing loss. First let usconsider some of the symptoms in a profoundly deafchild. The profoundly deaf child will not reach thesecond stage of language development, that is,receptive language. For months nothing abnormalmay be noticed. Some parents may observe at avery early age, 4 to 5 months, that the child doesnot respond to sounds, but frequently the firstsymptom which arouses suspicion is lack of speechdevelopment. The child produced babbling noisesin early infancy but he did not form any definitespeech sounds at the appropriate time. Later, whenthe child has a desire to communicate something tohis parents but is not able to do so, signs of frustra-tion appear. It may assume forms of tantrum orviolence. He may try to communicate more fre-quently and forcibly by crying or gesticulation.When the stage of babbling has passed, the childmay not use his voice any more, and will gesticulatemore frequently.Some other signs suggestive of deafness in infants

are response to some noises as opposed to voice;augmented visual vigilance and attentiveness; alert-ness to gesture and movements; yelling, screechingto express pleasure, annoyance or need.

Often it is reported that such a child is terrifiedin the dark. A normal child, when put to bed,and the lights are switched off, hears a variety ofambient sounds. Ambient noises surrounding usday and night are full of meaning, and many havea significant emotional value. A normal child doesnot usually feel cut off from the outside world inthe dark. A deaf child is plunged into completeisolation and loneliness.

These symptoms are not unusual in other cate-gories of children and may have different causes.The important thing is, that when causes are con-sidered, deafness should be at the top of the list.Often it is not on the list at all.

If a child does not speak within reasonable limitsof the normal age, it should be always considered

that his hearing is impaired, unless proved otherwiseby appropriate testing.The picture will be different in the child with

severe partial deafness. He may arrive at the stageof receptive language but somewhat later than thenormal age. He hears a variety of speech sounds,and initially he attaches the correct meaning to somewords, but later, when his activities involve him innew situations and he is presented with a greatervariety of words, his difficulties gradually increase.The following will explain the causes of some of

the difficulties a partial deaf child has to face:Normally, acoustic wave forms of different shapes

are responsible for significant variations of auditorysensations. They form different patterns of excita-tion in the appropriate centres of the central nervoussystem. In the case of the deaf individual, acousticwave forms of different shapes may produce identicalor similar sensations, and discrimination may bevery difficult. Different words may sound muchthe same to the child, but it seems to him that hisparents attach on occasions different meanings towhat to him sounds the same, e.g., the words'bottle' and 'water' may sound something like 'o-a'on both occasions. But at one time his mother willpresent him with a bottle, and on another occasionshe will point to water in the bath. Still later, whenthe child will try to use expressive language, and willask for one thing, saying something like 'o-a', andmeaning water, but will be presented with a thing(that is 'bottle') which he did not want, he will getfrustrated, angry and confused.

I have no space to describe this process in detail,and how it is modified according to the various typesof hearing loss in the partially deaf child. I canonly summarize some of the consequences.Language development will be retarded, a speech

defect will develop, usually an articulation defect(some consonants will be missing, mispronouncedor confused with others), the voice may have goodintonation (in the almost totally deaf child taughtto speak, intonation is lacking, and the voice ismonotonous and flat). The child will watchintently the speaker's face, and may acquire a fairamount of lip-reading which will enable him tounderstand much of speech in teteaa-tee conversa-tion (in some intelligent children surprisingly well).In unfavourable circumstances they may not hear ormay not understand what is said. Frequently theyare accused of not listening, being inattentive, lazy,and are punished for it. In fact, because of thelimitations of their communicating ability, theirpower of attention to speech is affected. Attentionis a function which selects, out of a total mass ofincoming signals those which have certain character-

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istics, and so doing avoids overloading themechanism which carried out the final analysis ofspeech (Broadbent, 1954). A deaf person, com-municating through a channel of limited capacityfor which the rule of all or nothing applies, cannotrely on a selection from a mass of incoming signalsautomatically-he must pay attention all the time-and he soon tires. Finally he cannot pay attentionat all. At school he remains backward. He maynot be able to localize the source of various sounds,and often is puzzled by this, or he may not be ableto determine what made what type of sound.

In another case, speech may be unintelligible.The child may use a jargon, perhaps intelligible tohis mother but to nobody else. Because of inabilityto communicate, extreme degrees of frustration mayappear, and he also will try to communicate increas-ingly by crying, shouting and gesticulation. Somewill gradually give up listening even to what theycan hear, because it does not mean much to themor confuses them. They withdraw into a silentworld because a hearing one causes them onlytrouble. On this account they may be assessed astotally deaf, and sent away to a residential deafschool, in spite of the fact that, with early detectionof the true type and degree of their hearing loss andadequate auditory training, they could make satis-factory progress in a normal school and live a normalhome life. They may be misdiagnosed altogetherand declared mentally defective. The differentialdiagnosis between mental deficiency, or low mentalcapacity and deafness is the most important one.No child should be declared mentally deficientwithout making certain that his hearing is normal.

In summary we can say that the early detectionof partial deafness on the whole is much moredifficult than the severe, almost total hearing loss.This is important when it is realized that numericallythis partially deaf group is larger. The defect maybecome obvious to a lay person comparatively late.Even to certain specialists the significant symptomsand serious consequences of this type of deafnessare comparatively unknown.What are then, under present conditions, the

chances of early detection and correct diagnosis ofdeafness? Theoretically there are three, so to say,lines of defence: (1) Screening all children withoutexception; (2) screening those in whose history thereis a possible cause of deafness; (3) observation andtesting children with a definite symptom known tobe associated with deafness.

(1) The first case, that is routine testing of allchildren at an early age, is not practicable as yet.Screening of schoolchildren soon after their entryto infant school is carried out, as a routine, in many

counties. About 1 % to 2% of these are found withsome degrees of significant hearing loss. Some ofthese have a serious hearing loss, and at this stagealready much valuable time has been lost, andfrequently much harm has already occurred.A satisfactory screening test for infants has not

been worked out yet. They can be tested, but thisneeds a special set-up and experience.

Attempts are made in some places to train healthvisitors and teach them to apply simple tests, buton the whole it is not satisfactory. There is alwaysa danger that the severe or moderately partially deafchild will be missed. One of the contributionshealth visitors can make is education of the public.When they visit homes, they can draw the attentionof mothers to the possibility of deafness.The knowledge of the public in these matters is

surprisingly limited. Authors of numerous books,meaning to give various types of advice to parentsof young children, show complete ignorance of thisproblem almost without exception.We must admit that there is no satisfactory

screening test available for the early detection ofthese types of hearing loss. There is a positivedanger in applying crude screening tests at thisstage. Partial deafness may not be recognized.When its effects become apparent at a later stageof development, the fact that the child has beenpreviously labelled (as a result of a crude screeningtest) as of 'normal hearing', or 'not deaf', may leadto the alternative diagnosis, that is mental back-wardness. The child may remain labelled as suchfor a long time before the true nature of his troublesis disclosed.

(2) Screening of children with a known possiblecause of deafness in their history is a more practic-able approach. If there is a definite history of someof the causes of deafness, one should not wait tillpronounced symptoms appear. This is considered,and with some justification, an ideal which cannotbe achieved in practice. Still, it could be achievedprovided the cooperation of everyone concernedwith the welfare of the child would be forthcoming,and I would include the obstetrician, thepaediatrician and the medical officer of health.

If there is a history of deafness in the family; if achild's mother had rubella or any other virus diseaseduring a critical stage of pregnancy; if the childsuffered from anoxia at birth, or from asphyxia ina premature child, or the labour was unusuallyprotracted, and the delivery was complicated; ifthe child had haemolytic disease of the newborn orwas jaundiced as a result of premature birth or hadkernikterus, in all these cases the offspring shouldbe tested without exception at an appropriate time.

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This approach has great possibilities from thepractical point of view of detection, and also it wouldadd significantly to our knowledge of the incidenceand pathology of certain types of deafness. Studieshave been, so far, almost exclusively retrospective.The above approach would provide us with valuableprospective types of investigation.

(3) The third type of approach, the one practised,is testing children with a symptom or sign knownto be associated with deafness. Lack of speech;retarded language development; speech defect;sigmatism (that is, mispronunciation of 's' or anysimilar confusion of speech sounds in a similarrange of frequency); lack of speech comprehension;serious emotional frustration combined with variousdegrees and types of speech defect; general back-wardness at school; those who suffer from a condi-tion known to be associated frequently with a hearinging loss, such as paralysis of cerebral origin; post-meningitic and post-encephalitic conditions; historyof fractured skull or severe head injury; cleft palate,and of course various types of middle-ear disease.But even this approach is not as yet fool-proof. Forexample, not all children with cerebral palsy havetheir hearing tested, and not all who had a cleftpalate, a speech defect, or those who survived aftercerebrospinal or tuberculous meningitis. They allshould have, without exception, their hearing fullytested.

I must mention now a few principles concerninghearing tests:

(1) There is no single form of testing which willgive a complete picture of the total hearing capacityof an individual.

(2) One should not draw any far-reaching con-clusions or make final decisions on the basis ofobservations carried out on one single occasion.

(3) Hearing tests are subjective tests requiringcooperation. There is no mechanical device whichwould enable us to test a child without gaining hisconfidence or cooperation. The handling of thechild is decisive.

(4) A test should be of such a nature that it shouldnot be associated with unpleasant or frighteningexperiences. A procedure which is associated withsuch experiences is, from our point of view, noprocedure at all. The child's cooperation will berequired in increasing degrees for future testing andrehabilitation. Destroying it at the very beginningin any way defeats the purpose of his attendancefor examination.

(5) The child's obvious reaction to certain soundsor his understanding of familiar speech sounds intete-'a-tete conversation does not mean that thechild could not have a hearing loss. When deafness

is suspected, only a complete test is conclusive. Theall or nothing rule applies to hearing tests, e.g., whenhearing for pure tones is tested, we obviously do nottest only for isolated frequencies in a haphazardmanner. When hearing for speech is tested, ahaphazard collection of words or sentences cannotgive a conclusive result. A list of phoneticallybalanced words and sentences must be used, andacoustic conditions of the room must be considered.There is a variety of testing methods available:

Observation of reactions to percussion instruments,to speech sounds, or pure tones; audiometric testsfor pure tones; live voice tests consisting ofphonetically balanced, specially selected, word andsentence lists. The child can be observed in a playsituation or conditioned to perform certain simpleactions to a definite sound stimulus. With infants,instructions can be given to the parents how tocondition a child to certain sounds at home, or howobservations should be carried out and recordedover a period of time.At a very young age we can always give a reliable

answer at least to the following questions; Is thischild totally deaf ? Is he severely deaf? Is hemoderately deaf? Is his hearing within normallimits? This is enough for the necessary urgentmeasures to be taken for treatment, if this isindicated. Gradually one can obtain more informa-tion, and within a reasonable time one can get acomplete picture about the child's capacity to hearand measure his hearing loss exactly.When the effect of the hearing loss on a child and

prognosis is considered, one should not do so onthe basis of the hearing loss alone. A careful studyof the learning ability is of greatest importance.Mental ability, personality, and emotional conditionof the individual modify the hearing disability. Onthe other hand the hearing disability, which affectsa growing organism, will influence the intellectualand emotional development of the child. In fact itis essential to consider the child as a whole.

Associated symptoms may necessitate a modifica-tion of testing procedures, and also they can be animportant guide in our search for possible causesand pathology of deafness. For example, a slightmuscular incoordination, which might have beenoverlooked because it did not cause a markeddisability, may disclose the cause and pathology ofdeafness in that child, that is kernikterus. Similarlyphysical examination may disclose, for example, anabnormally wide nasal bridge, combined with adeformity of the inner angle of the eyelids (epicanthalfold, occasionally combined with different colouredeyes, or a white forelock) and so disclose the specialtype ofhereditary deafness associated with these signs.

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THE IMPORTANCE OF AUDITORY COMMUNICATION 235

This points to what I said previously, and evenat the cost of repetition I want to emphasize again,namely, that it is important to study not an isolatedsymptom, but the individual as a whole. It cannotbe otherwise with a symptom like deafness, whichis basically a communication disorder and has sucha profound influence on the whole person. Thisalso indicates another important necessity: thestudy of the individual as a whole can be carried outonly by a clinician. That is the reason why I wouldemphatically say that the answers to the fundamentalproblems of deafness will not be given by techniciansbut by clinicians. Obviously this work cannot bedone by an individual or a single speciality. Itrequires the work of a team. Individuals interestedin special aspects of deafness joined to form suchteams, and this was the foundation of audiology.The otologist, teacher of the deaf, physicist,audiology technician, experimental phonetician,educational psychologist, school medical officer, arepart of such a team. I think, however, that repre-sentatives of some other specialities are still missing,

and one of the most important members of anaudiology team should be a paediatrician.

I will end by quoting the words of an eminentworker in the sphere of child health, Gesell (1956),who said:

'It is not normal to be deaf, but the deaf can beremarkably normal as individual personalities if weguide them into the right methods of managing theirhandicap. Our aim should not be to convert thedeaf child into a somewhat fictitious version of anormal hearing child, but into a well adjusted, non-hearing child, who is completely managing thelimitations of his sensory defect.'

REFERENCESBroadbent, D. E. (1954). Attention and Memory in Listening to

Speech. (Paper for symposium on speech, Acoustics Group,Physical Soc., London.)

Dreyfus-Graf, J. (1950). J. acoust. Soc. Amer., 22, 731.Fry, D. B. and Whetnall, E. (1954). Lancet, 1, 583.Gesell, A. (1956). Volta Rev., 58, 117.Licklider, J. C. R. (1950). J. acoust. Soc. Amer., 22, 820.Myklebust, H. R. (1954). Auditory Disorders in Children. New

York.Pratt, K. C. (1950). 'Child Development-Early Infancy.' In

Monroe, W. S., Encyclopedia of Educational Research, rev. ed.New York.

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