DOCUMENT RESUME

ED 112 587 EC 073 812

AUTHOR Garrett, Charles W., Ed.TITLE Selected Research, Development and Organizational

Needs of the Hearing Impaired.INSTITUTION National Academy of Engineering, Washington, D.C.

Committee on the Interplay of Engineering withBiology and Medicine.

SPONS AGENCY American Foundation for the Blind, New York, N.Y.;National Institutes of Health (DREW), Bethesda,Md.

PUB DATE May 73NOTE 36p.

EDRS PRICE MF-$0.76 HC-$1.95 Plus PostageDESCRIPTORS *Aurally Handicapped; Exceptional Child Research;

*Hearing Aids; *Research Needs; Research Projects;Sensory Aids; State of the Art Reviews

IDENTIFIERS *Needs Assessment

ABSTRACTIdentified are research, development, and

organizational needs regarding sensory aids for the hearing impaired.Discussion of the present status of sensory aids focuses on acousticand nonacoustic aids and points out that practical long-term utilityhas been extremely limited. Described are organizational and planningneeds such as demographic surveys, public information programs andsensory-aid centers, and research and development needs, such asquantification of residual perceptual capacity and evaluation ofexisting sensory aids. (LS)

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SELECTED RESEARCH, DEVELOPMENT,AND ORGANIZATIONAL NEEDSOF THE HEARING IMPAIRED

Subcommittee on Sensory Aids

COMMITTEE ON THE INTERPLAY OF ENGINEERINGWITH BIOLOGY AND MEDICINE

NATIONAL ACADEMY OF ENGINEERING

Washington, D. C.

May 1973

SUBCOMMITTEE ON SENSORY AIDS

Committee on the Interplay of Engineering with Biology and Medicine

ROBERT W. ANN, ChairmanMassachusetts Institute of Technology

LESLIE L. CLARKAmerican Foundation for

the Blind, Inc.

FRANKLIN COOPERHaskins Laboratories, Inc.

PETER B. DENESBell Laboratories, Inc.

GEORGE FELLENDORFAlexander Graham Bell

Association for the Deaf, Inc.

LEON D. HARMONCase Western Reserve

University

HARRY LEVITTCity University of New York

PATRICK W. NYEHaskins Laboratories, Inc.

ARAN SAFIRMount Sinai School of Medicine

* * *

W. ROBERT MARSHALL, JR.Chairman, Committee on theInterplay of Engineering withBiology and MedicineUniversity of Wisconsin

Report available from

CHARLES W. GARRETTExecutive Secretary, Committeeon the Interplay of Engineeringwith Biology and MedicineNational Academy of Engineering

National Academy of Engineering2101 Constitution Avenue, N. W.Washington, D. C. 20418

ii

NATIONAL ACADEMY OF ENGINEERING

The National Academy of Engineering wasestabiished in December 1964. TheAcademy is independent and autonomous inits organization and election of membersand shares in the responsibility given theNational Academy of Sciences under itscongressional act of incorporation to advisethe federal government, upon request, inall areas of science and engineering.

The National Academy of Engineering, aware of itsresponsibilities to the government, the engineering community,and the nation as a whole, is pledged:

1. To provide means of assessing the constantlychanging needs of the nation and the technical resources thatcan and should be applied to them; to sponsor programs aimedat meeting these needs; and to encourage such engineeringresearch as may be advisable in the national interest.

2. To explore means of promoting cooperation inengineering in the United States and abroad, with a view tosecuring concentration on problems significant to society andencouraging research and development aimed at meeting them.

3. To advise the Congress and the executive branch ofthe government, whenever called upon by any department oragency thereof, on matters of national import pertinent toengineering.

4. To cooperate with the National Academy of Scienceson matters involving both science and engineering.

5. To serve the nation in other respects in connectionwith significant problems in engineering and technology.

6. To recognize in an appropriate manner outstandingcontributions to the nation by leading engineers.

PREFACE

In June 1967, the National Academy ofEngineering established the Committee on the Interplay ofEngineering with Biology and Medicine under a contractwith the National Institutes of Health. The broad purposeof the Committee is to delineate the ways in which engineer-ing theory and practice can contribute to the solutions ofproblems in biology and medicine.

The Committee formed subcommittees toaddr,Iss some pertinent topics. The Subcommittee onSensory Aids was formed in 1969 to, stimulate, initiate,innovate, and correlate research into and development,evaluation, and deployment of sensory aids for the hearingand visually impaired. Through meetings, the pursuit oftheir own research, and their familiarity with other investi-gators and projects in- the United States and abroad, themembers of the .Subcommittee have become aware of currentsensory-aid needs, accomplishments, and opportunities.

The primary purpose of this report is toidentify areas that warrant further research and development.Topics are described briefly and categorized as pertaining toeither research or organizational and planning needs. Thereport is not intended to imply that none of these topics isreceiving attention. Work in several subjects is underway atvarious places- in this country and elsewhere.

This report is not a detailed review- of the stateof the art of sensory-aids for the hearing impaired, nor doesit deal explicitly with the requirements for such aids and tech-niques. Those important subjects were covered in a- specificSubcommittee conference on sensory training aids for thehearing impaired, attended by a select international group of

engineers, speech and auditory scientists, physicians, andeducators. Other aspects of sensory-aid evaluation werecovered in a similarly structured conference on the evaluationof mobility aids for the blind. Proceedings of both confer-ences are available from'the National Academy of Engineering.

The Subcommittee recognizes the urgent need forfocusing and structuring national efforts in sensory-aid re-search, development, evaluation, and deployment. A report,"Sensory Aids'fOr the Handicapped: A Plan for Effective Action,"establishes the rationale of such efforts and the benefits, botheconomical and humane, to be derived from them. It also delin-eates alternative mechanisms to link research and social needsto stimulate the development and use of appropriate sensory-aids for the blind and deaf.

Although we hope that the contents of this report willreceive the attention of those already involved in sensory-aiddevelopment and application, it is directed especially at thedynamic teacher and clinician whose experiences and ideas cancontribute to the greater efficacy and adoption of sensory aidsfor the hearing impaired. Equally important, the report isintended to mirror needs and opportunities for those benefactors- -both government and private--who may be seeking to identifyworthwhile projects for application of their resources and whoare responsible for organizing the nation's capacity to implementeffective programs.

*Proceedings of the Conference on SensoryTraining Aids for the Hearing Impaired. H. Levitt andP. W. Nye (Ed.). National Academy of Engineering,Washington, D. C. , 1971. Proceedings of the Conferenceon the Evaluation of Mobility Aids for the Blind. P. W. Nye (Ed.),National Academy of Engineering, Washington, D. C. , 1971.

vi

Finally, we hope to stimulate new conceptsand encourage creative minds to enter this exciting arena.We offer to scientists and engineers seeking new applicationsfor their talents a field that is both intellectually challengingand humanly rewarding.

Robert W. Mann, ChairmanSubcommittee on Sensory Aids

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ACKNOWLEDGMENTS

The Subcommittee on Sensory Aids acknowledgesthe significant contributions to its deliberations made bythree of its former members (now consultants to the Sub-committee): Dr. James C. Bliss, Stanford.ResearchInstitute; Dr. James L. Flanagan, Bell Laboratories; andDr. Carson Y. Nolan, American Printing House for theBlind.

In addition, a debt of gratitude is due Subcom-mittee member Harry Levitt, who assembled the text; toCharles W. Garrett, Executive Secretary of the Subcom-mittee, who offered valuable comment and edited thedocument; and to Marianna Shepard, who diligently andcapably typed the manuscript and prepared the camera-ready copy of this report.

This study and report were supported by theNational Institutes of Health under contract PH 43-64-44,task order 39, June 1967, and by a grant from theAmerican Foundation for the Blind, New York City.

CONTENTS

INTRODUCTION

PRESENT STATUS 3

Acoustic Aids 4Nonacoustic Aids 5

Other Types Of Aids 7

Methods of Evaluation- 7

Summary Assessment 7

DESCRIPTION OF SELECTED NEEDS 9

Organizational and Planning Needs

Demographic Surveys 9Public Information Programs 9Multidisciplinary Interaction 10Sensory-Aid Centers 10Wider Use of Existing Sensory Aids 11

Research and Development Needs 11

Fundamental Research on Speech andLanguage Acquisition in HearingImpaired Children 11

Quantification of Residual Perceptual.Capacity 12

Improvement of Diagnostic Technique s 13Development of Evaluation Procedures 13Evaluation of Existing Sensory Aids 14Improvement of Conventional Hearing Aids 15

Summary 1 6

Organizational and Planning NeedsResearch and Development Needs

EPILOGUE

CITED REFERENCES

OTHER PERTINENT DOCUMENTS

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INTRODUCTION'

A coordinated program of research and developmentin the field of sensory aids is necessary if the potential ofcurrently available knowledge for meeting the needs of thedeaf is to be realized. This document itemizes research anddevelopment needs-to outline the components of such a pro-gram and to stimulate the development of individual researchproposals. The areas selected, in the collective judgment ofthe National Academy of Engineering's Subcommittee onSensory Aids, would contribute most to such a coordinatedprogram.

During the early stages of a coordinated program,broad questions must be addressed: What is needed? Bywhom? What gaps in our knowledge of the deaf must be filled?What are the fundamental perceptual, physiologic, and tech-nical areas that require support? The few demographicstudies that exist need considerable extension to answer thesequestions.

Hearing is strongly coupled to a human activity ofimmense importance -- speech. It is also the basic mechan-ism by which a normal child develops the essential tool forcommunication and abstract thought -- language. The deaf,therefore, require sensory aids not only to facilitate commun-ication in general, as do the blind, but also to help specifi-cally in the acquisition of language.

Modern technology provides a variety of sensory aidsfor the deaf. The operating principles are either to amplifysound as much as possible, using whatever residual hearingthe deaf may have, or to detect some acoustic features andtransform them into signals in othei areas of the auditoryspectrum or into other sensory modalities. However, althoughthe essential technology for such devices is well established,

in general their merit has not been evaluated, and optimalmethods for using thein or for training users in their appli-cation are essentially unexplored.

The goal of our Subcommittee is to speed the devel-opment of devices and systems that are of direct and extensiveutility to the hearing impaired. In the pages that follow, wefirst offer some general assessments of the present status ofthe field and then list 11 specific projects that warrant immed-iate attention. Principal stress is placed on determining thebest means of using and deploying existing sensory aids,on methods of device and system evaluation, and on determin-ing optimal. methods of training. Although adequate hearingimplies an ability to perceive a great variety of sounds, be-cause of its overwhleming importance, speech is given greatemphasis.

The 11 project descriptions are not intended to be ex-haustive; rather, they are suggestive and are meant to stimu-late further interest and exploration. A final summaryprovida short abstracts and classifies the listed projectsinto those of an organizational nature and those involvingsensory-aid research and development. In neither sectionis any rank ordering of importance of the listed projects in-tended.

The references listed at the end of the report representthe best available statements on the state of the art and willlead- the reader to the bulk of the literature on the varioustopics.

The Subcommittee invites comment and queries,addressed to:

National Academy of Engineering2101 Constitution Avenue, N. W.Washington, D. C. 20 418

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PRESENT STATUS

The acquisition of language and satisfactorycommunication by speech are two different, although related,activities. This bears on sensory aids for the deaf in thefollowing way: A person who loses his hearing after learningto speak will retain his speech, despite a tendency for itsquality to deteriorate. Also, a relatively mild hearing losscan be adequately overcome with conventional hearing aidsthat amplify the important acoustic energy of speech. Hence,those who become deaf after acquiring normal language andspeech may need only special training in the use of an avail-able and effective sensory aid. However, a child who isborn with a hearing impairment or who loses a substantialportion of his hearing prelingually - i.e., before the age ofabout 2, will not autonomously learn to speak or to perceivespeech. He will need assistance in the acquisition of lan-guage, as well as aids to facilitate the development of oralcommunication skills, both expressive and receptive. Veryearly diagnosis and treatment of such cases is vital.

Thus, the three classes of communicationproblems of deafness -- hearing, language, and speech --necessitate different kinds of sensory aids. One, such asthe conventional hearing aid, is designed to transmit andamplify acoustic signals from the environment. The secondis designed to facilitate the ability to acquire language andincludes devices -to present information in a programed fashion,using visual and/or tactile clues. The third provides a mediumdirected toward the development of speech, the improvementof speech intelligibility, and the remedy of speech errors.

What approaches to sensory aids are available?A most attractive one, the acoustic approach, takes advan-tage of whatever hearing a deaf person may possess. This isnot as impractical as it might sound; few people are totallydeaf. The great majority of the hearing impaired have some

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residual hearing that, at least to some degree, is poten-tially usable with auditory training and with a properlychosen sensory aid. In another approach, the nonacoustic,the acoustic signal is transformed and presented in anothersensory modality. The two types of sensory aids associatedwith these approaches are discussed briefly below.

Acoustic Aids0,0

Complete absence of auditory response amongthe deaf population is very 'rare. As a consequence, theeffort to take advantage of residual hearing has led to thedevelopment of two types of sensory aids in the acousticclass.

The more common one involves nothing morethan sound amplification as provided by conventional hearingaids, the acoustic energy being delivered either by air -con-duction or by bone-conduction receivers. The rationale forthis type of aid has merit: Some auditory information isbetter than none, and the aids are readily available. Formany profoundly deaf, the auditory information providedwill include minimal characteristics of vowels, intonation,and rhythm, as well as valuable orientation clues. As notedabove, the acoustic amplification provided by these aids isof great benefit to those with less severe hearing impairment.

Same information on the optimal acoustic de-sign of sound-amplifying aids is available. l' 2 However,further extensive research is required on optimal frequencyresponses, on the use of automatic gain control and outputlimiting, on custom fitting, on the use of binaural aids, onportability, and on the design of group aids for use in class-rooms of hearing -impaired children. The acoustics of manyclassrooms are unsuitable for making the best use of hearingaids; further experiments on and dissemination of informationabout optimal classroom acoustics are needed.

An important additional consideration in thedesign of such aids is that today they are often placed onbabies in their first few months of life. It is not sufficient

to design instruments solely for adult consumers. In de-signing aids for infants, attention must be given to reliability,simplicity, size and weight of the aid, earmold design foryoung and growing ears, and tlie fact that an infant wearer isnot capable of compensating for imperfect performance.

The second type of acoustic sensory aid trans-forms speech signals. Broadly speaking, there are two kindsof transformational aids. In one, the speech:significantacoustic spectrum is compressed to,a range more nearly com-parable with the residual-hearing range. For example, sig-'nals in the speech-frequency bandwidth, 100-3,500 Hz, canbe compressed and shifted downward to reside within 50-1,750Hz. Features of spectral shape may be acoustically preservedafter the transformation. Empirically, tests are made to de-termine whether the resulting acoustb. signal can be assimi-lated and its information content taught. There is no substan-tial evidence yet that this spectral compression approach iseffective. The other kind of acoustic transformational aidpotentially has many forms. An ultimate form would convertany natural acoustic segment, presumably phonetically related,into an optimal acoustic replacement. Production of such adevice is remote. One device under test transposes the high-frequency energy of fricatives to low-frequency energy by aspecial countdown procedure for zero crossings of the acousticwaveform. 3 The natural speech spectrum is otherwise un-changed.

Nonacoustic Aids

Nonacoustic sensory aids are designed to usevision and/or the tactile sense as the avenue of communication.Devices using touch convert sound into mechanical vibrationor use electrodermal stimulation. 4 In one approach, a vibra-tortor is driven by the filtered speech signal. ' In another, thespeech signal is analyzed in real time and divided into frequencybands; the average amplitude of each band- is used to modulatesimultaneously an array of stimulators applied to skin areas(e.g. , each of the fingertips). 7-9

51-;:

Current results indicate that tactile signals maybe useful as a supplement to speech reading (i.e lipreading) 10or as an aid in speech training. 11 It must be recognized thatfor the deaf- person speech reading is usually the primary sourceof input; any device that will improve the reliability of thismode of communication is much to be desired. Tactile cluesthat augment speech reading, particularly with regard to thetiming of spoken communication, would appear to have valuablepotential for exploration.

Visual display of the speech signal has takenmany forms. The 'most elaborate has been the Visible SpeechTranslator, 12 -14 which offers a real-time representation ofthe speech spectrum on a cathode-ray tube. Specializeddisplays of frication, nasality, intonation, vocal intensity,vowels, and other speech characteristics are also available. 15, 16

The displays may appear on cathode-ray tubes, meters, banks oflights, eyeglasses, and even some ingeniously designed toysintended to hold a young child's attention during training periods.

The applicability of many of these deviceseither to speech training or to communication between and withdeaf people is discussed in recent surveys. 17 -20 With thesedevices, some modest successes have been. reported in speechinstruction. 21

Another class of devices would bypass theperipheral receptors in the body. Electrodes implanted inthe auditory nerve or in the brain would electrically stimulatethe- nervous system. Research has- been limited, and the outlookfor practical implementation soon is not promising. 22, 23

Finally, there is a large class of devices thatdo not operate on the acoustic speech signal. A number offorms are being tested or are in use, especially those trans-mitting manual languages and writing (classic sensory aids).Telephone communication is feasible through the use ofalphanumeric pushbutton signaling, picture transmission, andteletypewriter services. 24

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Other Types of Aids

Some aids (perhaps not properly termed "sensory")that at least partially automate training are potentially valuable.A hearing person is usually the only available interpreter linkinga normal speaker with a deaf per son. The hearing person alsoprovides the needed feedback to a deaf peison learning to speak.Automated teaching methods applied to auditory training arebeing tested, 25 and automated teaching of restricted features ofspeech is possible now. Through the use of digital computers,more complicated recognition and training algorithms arefeasible. 2°, 27

Methods of Evaluation

Evaluation of sensory aids for the hearingimpaired is difficult; the territory is virtually uncharted.Conventional intelligibility tests adopted from telephoneengineering apply to only a few components of the communicationproblems of the deaf. Such tests are widely recognized ,asunsatisfactory, but there has been little- effective development ofsupplements. Effective two-way communication requires muchmore than good one-way articulation or intelligibility scores.Of even greater concern is that the evaluation may concentrateon too narrow a problem. The deaf person is faced with amultitude of problems, and it is possible for a device to behelpful in one and detrimental in others. Extensive researchin evaluation -is required.

Summary Assessment

Although many sensory aids are ingeniouslydesigned and earnestly applied, practical long-term utilityhas been extremely limited. This is primarily because mostdesign has been ad hoc, many of the perceptual requirementsremain unknown, and effective training and evaluationtechniques are embryonic. Teachers and therapists working

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with the deaf frequently have not been convinced of thevalue of devices, even when available, and thus have notsupported their use. Furthermore, we have only arudimentary knowledge of the basic processes of speechand language, and ,understanding of what is truly essentialfor effective communication is still lacking.

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DESCRIPTIONS OF SELECTED NEEDS

Organizational and Planning Needs

Demographic Surveys: The need for aids to train andassist the hearing impaired to communicate effectivelyhas long been recognized. The hearing impaired popu-lation is highly heterogeneous, with diverse needs; forexample, the needs of a congenitally deaf child are verydifferent from those of an adult with gradually deterioratinghearing. Furthermore, the type of sensory aid best suitedfor a particular child may depend heavily on such factors asetiology, degree of hearing impairment, and age of onsetof hearing impairment. Much valuable information can beextracted from currently available Public Health Servicecensus data28 and-.other surveys29' 30 on the incidence ofdeafness in the United States, but more demographicinformation is required to define and categorize sensory-aid needs and to establish priorities for research ondevices and systems to meet these needs.

Public Information Programs: Deafness is not a conspicuoushandicap, yet the effects of a- severe hearing impairmentare overwhelming, particularly to a prelingually deaf child.The general public appears to be largely unaware ,of thedebilitating effects of profound deafness, presumably becausetheir exposure to hearing impaired persons is limitedprimarily to those with relatively minor hearing impairments.The situation is not improved by the many tasteless jokes inour society that involve hard-of-hearing persons- and thatbelie the seriousness of a severe hearing handicap. Muchneeds to be done to educate the public about the less obviousbut more severe implications of deafness, the extent towhich aids and special training can assist the hearing impaired,and the importance of- subsidizing, through both public andprivate funding, research and services for the hearing impaired.

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Multidisciplinary Interaction: Research in sensory aids forthe hearing impaired encompasses a number of disciplines,including engineering, medicine, psychology,, physiology,speech sciences, linguistics; audiology, and education.Because of the disproportionately large range of disciplinesinvolved, there is an unfortunate lack of contact amongworkers in different fields. 'Methods of enhancing contactamong educators, researchers, and engineers include:

(1) organizing multidisciplinaryconferences and workshops onregular basis;

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(2) providing teachers with tutorialmaterial and seminars in speech,hearing, and 'linguistics, includingexposure to the latest researchfindings; and

(3) establishing fellowships forresearchers for full-time work inteaching and clinical environments.

Sensory-Aid Centers: To develop sensory aids for thehearing impaired, it is necessary to have research centersWith the appropriate facilities, personnel, and sense ofmission to provide a well-organized, coordinated attack onthe problem. Because of the broadly multidisciplinarynature of sensory-aid research and development, the effortsof several workers in -concert are necessary, therebyrequiring a fairly large laboratory or center, regional ornational. There is a volunteer corps of researchers whosechoices of subjects of investigation are constrained- bylimited research facilities, lack of day-to-day contact withothers working in related subjects, and meager financialsupport. As a result, the current research effort isuncoordinated and tends to be overly concentrated inperipheral subjects that provide small, manageable researchprojects for individual researchers. A major attack on the

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fundamental underlying problems is unlikely without somepooling of resources and talent in a larger framework.(Suggested approaches toward some form of nationalcenter, laboratory, or foundation are found in the NationalAcademy of Engineering publication, "Sensory Aids for theHandicapped: A Plan for Effective Action. ")

Wider Use of Existing Sensory Aids: A number of newsensory aids and associated techniques have been found towork well in objective evaluations, and these should beused as widely as- possible to obtain maximal benefits.Three projects that would have valuable and immediatebenefits at a moderate cost are:

(1) the establishment of a nationwideprogram for screening all high-risk babies for evidence of hearingimpairment and other sensorydefects;

(2)- the fitting of hearing aids to allinfants as soon as hearingimpairment is diagnosed; and

(3) the provision of teletypewriters atnominal cost -to all hearing impairedpersons who need and can use them.

Research and Development Needs

Fundamental Research on Speech and Language Acquisitionin Hearing Impaired .Children: The science of- psycholinguisticsis in its infancy; little is known about speech and languagedevelopment in normal children and even less in the case ofdeaf children. Nevertheless, crucial decisions on theeducation of deaf children are continually being made. Akey assumption underlying many educational programs is thatlanguage acquisition in deaf children follows essentially the

same pattern as in normal children, except that the timescale is considerably extended. Recent developments inpsycholinguistics provide useful guidelines by whichlanguage development in deaf children may be measured.31-35It is important to establish whether language acquisition inthe deaf follows the same hiesarchy of development (albeiton an extended scale) as in normal children, or whethernew language forms are developed in a different manner.

The orientation of this research effortshould be concerned not only with the process of speechand language acquisition and with how it is affected byhearing impairment, but also with the determination of theremedial needs and what can be achieved. The phrase"speech and language" is used here in the belief that thetwo are intimately intertwined and that both oral and writtenforms of language should be investigated.

Quantification of Residual Perceptual

Capacity: The intellectual development of a deaf childdepends directly on all his perceptual abilities, includingresidual hearing capacity. Methods of quantifying visualand tactile information-handling capacity in the hearingimpaired child need to be investigated. Because hearingimpaired children frequently also suffer from other sensoryimpairments, that possibility must always be considered.

The specification of hearing impairmentonly in terms of an audiogram is clearly inadequate, andmore appropriate methods are- needed. Some research.on the relation between residual hearing and speech per-ception is in progress, 3' 37 but much more -is required.

The future development of sensory aidsdepends heavily on the extent to which residual hearingand other perceptual modalities can be used in the transferof information. The extent is crucially age-dependent andthis should- be considered in investigating intermodalitytransfer.

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The search for practical substitutes forspeech should be pursued. A promising approach thatmeiits immediate consideration is the presentation ofkey articulatory information (e. g. , place, manner,voicing cues) visually or tactually as an aid to speech-reading. 38-40 The problems of automatically extractingsuch information from the acoustic speech signal arenot trivial and need to be studied. 41

Improvement of Diagnostic Techniques: Closely linkedto the problem of quantifying residual hearing capacity isthat of obtaining an accurate diagnosis of hearing disorders.This is a constantly evolving process, but at present theemphasis should be on developing reliable audiometricprocedures for very young children and children withbehavioral problems or concomitant impairments. Alsorequired is the development of tests of communicationability that realistically predict a hearing impairedperson's performance in real-life situations (e.g., speechperception under noisy or reverberant conditions). Methodsof establishing measures of speech reception at the feature,syllable, sentence, and paragraph levels have beensuggested,'" and these techniques should be investigated.

Development of Evaluation Procedures: The evaluation ofsensory aids is neither simple nor trivial. Traditionally,objective evaluation procedures have compared a newdevice or technique with conventional devices or techniques.Unfortunately, "conventional" systems are not always welldefined or evaluated themselves. They may encompass awide variety of techniques of varied effectiveness.

A more serious problem lies in definingthe scope of the evaluation. A well-designed evaluationthat is narrow in scope may show a device to be effectivefor a specific task when, in fact, the impact of the deviceon a broader scale may be less than desirable. A simpleexample is a device that helps a deaf child produceindividual speech sounds correctly while detracting fromthe child's overall fluency by overemphasizing individualsounds.

re, 13 -4)"..)

In many cases, evaluation needs to takeplace in a school or clinic, in which, many variablesare beyond the experimenter's control. Practicalevaluation procedures need to be developed that areobjective, reliable, and simple to use, despite thediversity of uncontrolled variables in schoolrooms,clinics, etc.

Evaluation of Existing Sensory Aids: A number ofsensory aids 15, 16 that have been developed appearpotentially useful, but ,have not been evaluated in anydepth. Closely linked to the development of new devicesis the development of specialized training procedures foruse with these aids. Systematic, objective evaluation ofexisting sensory aids and training procedures is .urgentlyneeded. Apart from determining whether a new deviceor technique improves communication skills, _it isimportant to know in quantitative terms the strengths andweaknesses of existing aids, so that sensory aids ofimproved design can be developed.

Of the various sensory aids for the deafthat have been developed over the years, aids for speechtraining appear to be the most promising for the immediatefuture. Evaluation of such aids should take into accountrate of progress, transfer of skills, and retention of skillsafter termination of specialized training.

Efficiency of evaluation- is very important,and the use of sequential testing procedures should beconsidered as a means of terminating experiments as soonas significant improvement (or lack of improvement) isestablished. In the evaluation of speech training aids, oneshould consider the development of. semiautomatic orcomputer-controlled systems that permit several users toreceive concentrated training simultaneously from a singleteacher.

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Improvement of Conventional Hearing Aids: Considerableresearch is still needed on finding the optimal electro-acoustic characteristics of conventional hearing aids andon ways of fitting hearing impaired persons with aidsthat best meet their individual requirements. To do this,hearing impairments first have to be classified accordingto their origin and physiologic nature and to the social,educational, and communicative situations ;n which theyoffer serious handicaps. The hearing-aid requirements ofeach of these groups then will have- to be determinedexperimentally, and clinical procedures developed forfitting individuals with the most suitable aids. For adetailed review of work in this area, see Ling.43

A number of design improvements thatcould be introduced into commercial aids without significantresearch include smoother frequency-response curves,reduced nonlinear distortion (especially when battery powerbegins to drop), and practical directional microphones.The special problems of hearing aids for children - includingphysical robustness, small size, improved earmold designfor small and growing ears, and some means of monitoringexternally (e. g. , by the teacher) whether or not the aid isworking -- should be considered.

Optimal specifications need to be developedfor wearable hearing aids and for group hearing aids(wireless or loop types). The latter require considerationof frequency response, permissible degrees of distortion,and relative volumes of the teacher's voice, the child'sown voice, and other children's voices..

For more detailed information on research44needs for hearing aids, see Directions for Research. . . .

Summary

This report has identified eleven kindsof need grouped into two major categories.

'Organizational and Planning Needs:

1. Demographic Surveys: Collection of datathrough demographic surveys of thehearing impaired population to helpdetermine the need for special trainingand the kinds of sensory aids that wouldmost benefit that population.

2. Public-Information Programs: Stimulationof public awareness of the need for and thepotential of research for providing effectiveaids, a primary goal being the developmentof a favorable climate for- obtaining funds(both public and private) to support researchand services for the hearing impaired.

3. Multidisciplinary Interaction: Development ofmechanisms to overcome the severe lack ofcommunication among researchers, educators,and others and to enhance. mutual exposureand interaction among workers in differentspecialities.

4. Sensory-Aid Centers: Establishment ofnational centers for sensory aids to imple-ment programs in research, development,evaluation, and deployment.

5. Wider Use of Existing Sensory Aids: Thewidest deployment possible of the several exist-ing sensory aids that have shown a fair degreeof success in objective evaluations.

Research and Development Needs:

6. Fundamental Research on Speech andLanguage Acquisition in Hea g ImpairedChildren: Concentrated research on the natureof language acquisition in hearing impaired andnormal children not only to encompass thebasic process of language acquisition and itslink to hearing, but also to determine themajor remedial needs and possibilities. Investi-gations should keep in close touch with workcarried on in the practical training of deafchildren, where interesting observations areoften made that call for sound research to estab-lish their validity.

7. Quantification of Residual Perceptual Capacity:Coordinated research to measure residualperceptual capacities of the hearing impaired,including measurements of visual and tactileinformation-handling capacity of deaf personsand the quantification of commonly occurringconcomitant sensory impairments.

8. Improvement of DiagnoRtic Techniques: Improve-ment of diagnostic techniques, particularly withrespect to isolating the sources of failure incommunication, but with emphasis also on thedevelopment of reliable audiometric proceduresfor very young children and on developing testsof communication ability that can morerealistically predict performance in real-lifesituations (e. g. , speech reception by a hearingimpaired listener under noisy or reverberantconditions). New techniques should be explored.

9. Development of Evaluation Procedures: Develop-ment.of practical and objective evaluation proced-ures that take into account the total impact of theevaluated device or technique on the functioning

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of the user, including simple and reliableprocedures that can be convenientlyadministered with robust equipment inschools and clinics.

10. Evaluation of Existing Sensory Aids:Systematic, objective evaluation of existingsensory aids and training procedures todetermine which new devices and techniquesimprove communication skills and to knowin more quantitative terms the strengthsand - weaknesses of existing aids, so thatever better aids can -`be developed,

11. Improvement of Conventional Hearing Aids:Improvement of the design, fitting, andevaluation of conventional hearing aids (thesingle most important sensory aid for thehearing impaired), including the determinationof optimal frequency responses- and permissibledegrees of distortion, as well as the develop-ment of practical directional.microphones andhigh-power, low-cost aids with smoothfrequency-response curves. This should,, andprobably could, involve,both private and publicagencies.

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EPILOGUE

To those already involved in sensory-aid research and development, the Subcommittee'sassessment of urgent needs can serve as a checklistagainst which other views and proposals can be weighed.For those searching for new opportunities, it is hopedthat this brief discussion has provided a first step inthe process of identifying challenges and findig waysto meet them. Except for an occasional hint ofpotentially fruitful avenues that merit consideration,the creation of definitive projects in any of the subjectslisted is left to those who will carry them out. To aidin this endeavor, the following pages list basic sourcedocuments that define more completely the problems inthis field, describe the current state of the art, andindicate places and people currently active in the field.These source documents abound in reference citationsthat cover the relevant literature.

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CITED REFERENCES

,

1. Davis, H., Hudgins, C. V., Marquis, R. J., Nichols,R. H., Peterson, G.E., Ross, D. A., and Stevens,S. S., The Selection of Hearing Aids. Laryngoscope,56 (1946), pp. 85-115 and 135-163; based on the report:Davis, H. , et al. , Hearing. Aids: An Experimental Studyof Design Objectives, Harvard University Press,Cambridge, Massachusetts (1947).

2. Medical Research Council, Hearing Aids and Audiometers,London, H. M. S. 0. (1947). Medical Research CouncilSpecial Report Series No. 261.

3. Guttman, N. G., and Nelson, J. R., An Instrument thatCreates Some Artificial Speech Spectra for the SeverelyHard of Hearing. Am. Ann. Deaf, 113 (1968), pp. 295-302.

4. Saunders, Frank A., Electrocutaneous Displays. MontereyConf. on Tactile Communication, Systems and Devices,Smith Kettlewell Institute of Visual Sciences, San Francisco,California (April, 1973).

5. Guberino, P., Proc.:Int. Conf. Oral.Education of theDeaf, A. G. Bell Assoc. for the Deaf, Washington, D. C:(1967), pp. 730-732. Vol. I: The Use of Phonetic Rhythmsin the Verbotonal System.

6. Black, J. W., Perception of Altered Acoustic Stimuli bythe Deaf; Final Report, Res. Project 1688, Grant No.RD 1226-S-68-C4, Ohio State University Research Founda-tion, Columbui, Ohio (December, 1968).

7. Pickett, J. M., Tactual Communication of Speech Soundsto the Deaf: Comparison with Lipreading. J. Speech HearingDis., 28 (1963), pp. 315-330.

8. Pickett, J. M., and Pickett, B. H. , Communication ofSpeech Sounds by a Tactual Vocoder. J. Speech HearingRes., 6 (1963), pp. 207-222.

9. Gault, R. H., and Crane, G. W., Tactual Patterns fromCertain Vowel Qualities Instrumentally Communicated froma Speaker to a Subject's Fingers. J. Gen. Psycho's, 1

(1928), pp. 353 -359.

10. Martony, J. and Spens, K. E., Tactual and VisualLipreading Aids. Conference Record, 1972 Conference onSpeech Communication and. Processing, IEEE, New York(1972), pp. 242-245; to appear in IEEE Trans. AudioElectroacoust., (June, 1973).

11. Willemain, T. R., and Lee, F. F., Tactile PitchDisplays for the Deaf. IEEE Trans. Audio Electroacoust.,AU-20 March- (1972), pp. 9-16.

12. Kopp, G. A., and Kopp, H. C., An -Investigation toEvaluate Usefulness of Visible Speech Cathode Ray TubeTranslator as a Supplement to the Oral Method ofTeaching Speech to the Deaf and Severely DeafenedChildren, Final Report. Grant No. RD-526, Office ofVocational Rehabilitation, Washington, D. C. (1963).

13. Stark, R. E., Cullen, J. K., and Chase, P.. A.,Preliminary Work with the New Bell Telephone VisibleSpeech Translator. Am. Ann. Deaf, 113 (1968), pp. 205-214.

14. House, A. S., Goldstein, D. P., and Hughes, G. W.,Perception of Visual Transforms of Stimuli: LearningSpeech Simple Syllables. Am. Ann. Deaf, 113 (1968),pp. 215-221: See also Reference 12, Chapters 3 and 4.

15. Pickett,. J. M. (ed.), Proceedings of a Conference onSpeech Analyzing Aids for the Deaf. Am. Ann. Deaf, 113(1968), pp. 116-330.

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16. Levitt, H. , and Nye, P. W. Editors. TrainingAids for the Hearing Impaired, Proc. of a Conf. , Nat'lAcad. Eng. , Washington, D. C. (1971).

17. Pickett, J. M. , Recent Research on Speech-AnalyzingAids for the Deaf. IEEE- Trans. Audio Electroacoust. ,

AU-16 (1968), pp.- 227-234.

18. Risberg, A. , A Critical Review of Work on SpeechAnalyzing Hearing Aids. IEEE Trans. Audio Electroacoust.ATJ-17 (1969), pp. 290-297:

19. Pickett, J. M. , Status of Speech-Analyzing CommunicationAids for the Deaf. IEEE Trans. Audio Electroacoust.AU-20, March (1972), pp. 3-8.

20. Martony, J. , Visual Aids for Speech Correction: Summaryof Three Year& Experience, Paper 35 in Proc. Int.Symposium Speech Communication Ability and ProfoundDeafness, G. Funt (ed. ), A. G. Bell Assoc. for the Deaf,Washington, D. C. (1972), pp. 345-349.

21. Levitt, H. , Speech Processing Aids for the Deaf: AnOverview. IEEE Trans. Audio Electroacoust. , AU-21(1973).

22. Kiang, N. '1. S. , and Moxon, E. C. , PhysiologicalConsiderations in Artificial Stimulation of the Inner Ear.Ann. Otol. Rhinol. Laryngol. , 81, (1972), pp. 714-730.

23. Simmons, F. B. , and Glattke, T. J. , Comparison ofElectrical and Acoustical Stimulation of the Cat Ear.Ann. Otol. Rhinol. Laryngol. , 8.1, (1972), pp. 731-737.

24. Levitt, H. , and Nelson, J. R. , Experimental CommunicationAids for the Deaf. IEEE Trans. Audio Electroacoust. ,AU-18 (1970), pp. 2-6.

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25. Doehring, D. G., and Ling, D., Programmed Instructionof Hearing-Impaired Children in the Auditory Discrimina-tion of Vowels. J. Speech Hear. Res., 14 (1971), pp.746-754.

26. Kalikow, D. N., and Swets, J. A., Experiments withComputer-Controlled Displays in Second-Language Learn-ing. IEEE Trans. Audio Electroacoust., AU -20, March(1972), pp. 23-28.

27. Nickerson, R. S., and Stevens, K. N., An ExperimentalComputer -Based System of Speech Training Aids for theDeaf. Conference Record, 1972 Conference on SpeechCommunication and Processing, IEEE, New York (1972);to appear in IEEE Trans. Audio Electroacoust,, AU-21(1973).

28. Characteristics of Persons with Impaired Hearing, UnitedStates, July 1962 - June 1963, National Center for HealthStatistics, Publication 1000, Series 10, No. 35, U.S. Dept.of HEW, Washington, D. C. (1967).

29. Additional Handicapping Conditions, Age at Onset of Hear-ing Loss, and Other Characteristics of Hearing ImpairedStudents, United States, 1968-69, Office of DemographicStudies, Gallaudet College, Series D, No. 3, Washington,D. C. (June, 1970).

30. Schein, J. D., The National Census of the Deaf Popula-tion. Deafness Annual III Prof. Rehab. Workers with theAdult Deaf, Silver Spring, Md.; to appear June, 1973.

31. Stuckless, E. R., and Marks, C. H., Assessment of theWritl_pn Language of Deaf Students, Cooperative ResearchProject 2544, Contract OE-5-10-123, U. S. Office ofEducation, Washington, D. C. (May 1966). University ofPittsburgh, School of Education, 1966, 142 pp.

32. Taylor, L. T. , A Language Analysis of the Writing ofDeaf Children, Final Report. Project No. 19-2057,Grant No. OEG-4-9-192057-0009-032, U. S. Office ofEducation, Washington, D. C. (August, 1969). FloridaState University, Dept. of English, 1969, 202 pp.

33. Babbini, B. E. ,And Quigley, S. P. , A Study of theGrowth Patterns in Language, Communication, andEducational Achievement in Six Residential Schools forDeaf Students. Institute for Research on ExceptionalChildren, University of Illinois (1970).

34. Marshall, W. J. A. , and Quigley, S. P. , Quantitativeand Qualitative Analysis of Syntactic Structure in theWritten Language of Hearing Impaired Students. Institutefor Research on Exceptional Children, University ofIllinois (1970).

35. Kates, S. L. , Language Development in Deaf and HearingAdolescents, Final Report, SRS Research Grant RD-2555-S.The Clarke School for the Deaf, Northampton, Massachusetts(Feb., 1972).

36. Pickett, J. M. , Speech Science Research and SpeechCommunication for the Deaf in Speech for the Deaf Child:Knowledge and Uses L. E. Connor (ed. ). A. G. BellAssoc. for the Deaf, Washington, D. C. (1971), pp. 8^.-108.

37. Smith, C. R. , Residual Hearing and Speech Productionin Deaf Children, Ph. D. dissertation, City Universityof New York (1972). University Microfilms ReprintNo. 72-24, 156.

38. Upton, H. W. , Wearable Eyeglass Speech_ reading Aid,Am. Ann. Deaf, 113 (1968), pp. 222-229.

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ter

39. Goldberg, A. J., A Visual Feature Indicator for theSeverely Hard of Hearing. IEEE Trans. Audio Electro-acoust., AU-20 March (1972), pp. 16-23

40. Risberg, A., Research and Development Program onLipreading Aids, Paper 39 in Proc. Int. Symp. SpeechCommunication Ability and Profound Deafness, G. Funt(ed. ), A. G. Bell Assoc. for the Deaf, Washington,D.C., (1972), pp. 379-383.

41. Liberman, A. M., Cooper, F. S., Shankweiler, D. P.,and Studdert-Kennedy, M. Why are Speech SpectrogramsHard to Read? Am. Ann, Deaf, 113 (1968), pp. 127-133.

42. Miller, J. L., in Levitt and Nye (Ref. 16), p. 78.

43. Ling, D., Conventional Hearing Aids: An Overview.Volta Rev., 73 (1971), pp. 343-352; 375-383.

44. Directions for Research to Improve Hearing Aids andServices for the Hearing Impaired, Report on theMeeting of Working Group 65, Committee on Hearing,Bioacoustics and Biomechanics. National` Academy ofSciences - National Research Council, Washington; D. C.1February, 1972).

.

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I

OTHER PERTINENT' SOURCE DOCUMENTS

Human Communication and its Disorders--An Overview.Subcommittee on Human Communication and its Disordersof the National Advisory Neurological Diseases and StrokeCouncil, National Institute of Neurological Diseases andStroke. U. S. National Institutes of Health, Public HealthService, Bethesda, Maryland (1969).

Connor, L. E. (ed.), Speech for the Deaf Child: Knowledgeand Use. A. G. Bell Assoc. for the Deaf, Washington, D. C.(1971).

Levitt, H., Sensory Aids for1972 Carnahan Conference onsity of Kentucky, Lexington,

the Deaf--Key Problem Areas,Electronic Prosthetics, Univer-Kentucky (1972).

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