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ST 0853393 INDUSTRIAL DEAFNESS Hearing Testing and Noise Measurement Joseph Sataloff, M.D., D.Sc. (Med.) Assistant Professor of Otology, The Jefferson Medical College of Philadelphia; Visiting Professor of Audiology and Codirector of Industrial Deafness Course, Colby College; Consultant in Audiology, Veterans Administration; Audiologist to the Chil dren's Hospital of Philadelphia; Editorial Board, AMA Ar chives of Otolaryngology The Blakiston Division McGraw-Hill Book Company, Inc. New York Toronto London 1957 Contributors $T 0853394 CHARLES R. WILLIAMS, Ph.D. Director, Industrial Hygiene Services, Loss Prevention De partment, Liberty Mutual Insurance Company; Associate Professor of Applied Industrial Hygiene, Harvard Uni versity School of Public Health; member, American Stand ards Association Z24-X2 Committee and Committee on Noise, Associated Industries of New York ROBERT ROOP, Ph.D. Group engineer, Philco Corporation; chairman, American Standards Association Subcommittee Z24-X24 on Acoustic Testing; formerly senior physicist, Johns-Manville; for merly staff member, Acoustics Laboratory, Massachusetts Institute of Technology ROBERT GOLDMAN, Ph.D. Lecturer in Physics, Temple University; project engineer, Research Division, Philco Corporation; member, American Standards Association Subcommittee Z24-X23 on Fan Noise; author of papers on noise and acoustics JOHN A. ZAPP, JR., Ph.D. Director, Haskell Laboratory for Toxicology and Indus trial Medicine, E. I. duPont de Nemours & Co., Inc.; con sultant, Army Chemical Corps; member of several com mittees, National Research Council; author of chapter on Industrial Noise in Modern Occupational Medicine, by Fleming, D'Alonzo, and Zapp vii ST0853395 Preface The increase in industrial noise and a greater appreciation of deafness in general during recent years have focused attention upon industrial deafness, which is the loss in hear ing that results from exposure to intense noise. Emphasis on the medicolegal aspect of this condition has furthermore introduced a number of challenging problems that noisy industries must meet and resolve. Such industries need to consider: 1. How to achieve a better understanding of and a clearer perspective on all aspects of industrial deafness as it affects employees and management. 2. How to determine whether a noise problem exists, and if so, what steps are necessary to establish a practical and effective conservation-of-hearing program. 3. How to train industrial personnel to perform reliable and valid hearing tests. Considerable material has been published in the medical and acoustical literature in reference to these problems, but there has been no one volume that could be said to cover all phases of industrial deafness or to serve as a guide in solving the many problems now facing industry. This book attempts to fill these needs and concerns itself with all aspects of noise measurement and audiometric test ing. It is intentionally fundamental and is directed not to the acoustical expert but to industrial executives, industrial IX ST0853396 x Preface physicians, hearing testers, otologists, nurses, industrial hy gienists, and engineers. It is hoped that this book will make it possible for individuals with no previous experience in hearing testing or acoustics to acquire sufficient basic in formation and technique to perform measurements. Com paratively few bibliographic references are included because of the nature of the text, and the author and contributors have forsworn footnotes. At the end of the book, however, is included a bibliography of recommended articles pub lished in the medical and acoustical literature. Part I is intended to provide an over-all perspective of the various problems relating to noise and deafness. It covers the elementary physics of sound, how we hear, the causes of deafness, the medicolegal aspects of occupational deafness, and the basic problems involved in developing a conservation-of-hearing program. Certain complicated con cepts, particularly in the chapter on The Physics of Sound, have been simplified. Efforts have been made to avoid equa tions and complex explanations as well as equivocal opinions throughout the book. Part II is somewhat more technical and is intended for safety engineers, hygienists, and technicians concerned with noise measurements. It describes how to make noise meas urements and how to use the necessary equipment. It also discusses damage-risk criteria relating noise and deafness, the principles of noise control, and the factors to be con sidered in making a room suitable for audiometric testing. Part III is devoted to all aspects of hearing testing and is intended to serve as a guide and reference manual for indus trial hearing testers. The directions for performing reliable and valid hearing tests are presented in a simple, step-bystep, practical manner so that they can be used for training personnel. The n$ed for critical appraisal of testing tech niques and extensive training under supervision is empha sized. This section also describes methods of record-keeping and the details to be considered in organizing a conservationof-hearing program; it also discusses auditory fatigue, ma- ST-0853397 Preface xi lingering, and presbycusis. The roles of the industrial physi cian and otologist are presented in detail, and the principles of audiogram interpretation are demonstrated. In order to make the book as comprehensive as possible, the author has invited several specialists to provide certain chapters so that the reader may have the benefit of the most authoritative information available. For these contributions the author wishes to express his appreciation to Charles Wil liams, Robert Roop, Robert Goldman, and John Zapp. To William Heimback and William Gross of the Westinghouse Corporation for their suggestions on industrial relations and the responsibilities of the- engineer, and to Dr. H. Menduke for his criticism of the material on presbycusis, the author extends his appreciation. The author also expresses gratitude to a number of col leagues and friends whose sustained interest, criticisms, sug gestions, and encouragement have made this book possible: particularly to Drs. Frederick T. Hill, George M. Coates, and Frederick T. Harbert, and to those who comprise the faculty for the special course in Industrial Audiology given at Colby College, where Dr. Hill is director of the course. The differ ent perspectives, ideas, and methods in this book have been influenced to some degree by these men at Colby, among whom are Drs. Walter Rosenblith, Hallowell Davis, Aram Glorig, Wavne Rudmose, Charles Williams, Kenneth Stev ens, John Zapp, Jerome Cox, Ira Hirsh, and Stewart Nash. For the opportunity to conduct a conservation-of-hearing program in a large industry for the past seven years, and by so doing to obtain additional field experience, the author thanks Dr. C. D. Stull, industrial physician. The author also wishes to express his sincerest apprecia tion to Dale Phalen for his invaluable editorial assistance; and for continued patience in deciphering his handwriting during countless hours of typing and retvping, he is most grateful to his secretary, Nisa Delli-Pizzi. Joseph Sataloff ST 0853398 Contents Contributors Preface vii ix part one General Considerations 1 The Physics of Sound 2 How the Ear Functions 3 The Causes of Deafness 4 Effects of Noise on Human Behavior 5 Medicolegal Aspects btj Charles R. Williams 6 Conservation of Hearing in Industry 3 18 28 44 52 61 part two Noise Measurement 7 Principles of Noise Measurement by Charles R. Williams 8 Making Noise Measurements by Charles R. Williams 9 Damage-risk Criteria 10 Ear Protectors 11 Principles of Noise Abatement by R. B.Goldman 12 Audiometric Test Rooms by Robert Roop 77 96 113 124 135 148 part three Hearing Testing 13 Measurement of Hearing Loss 14 Audiometry xiii 169 181 f ST0853400 References A suggested partial list of available publications in the fields of noise measurement and hearing. General An Annotated Bibliography cn Noise, Its Measurement, Effect, and Control, Industrial Hygiene Foundation of America, Inc., Mellon Institute, Pittsburgh, 1955. Kryter, Karl D.: `The Effects of Noise on Man," Monograph Supple ment No. 1, Journal of Speech and Hearing Disorders, Wayne University, Detroit, 1950. National Noise Abatement Symposia, 1950, 1951, 1952, 1953, Armour Research Foundation of Illinois Institute of Technology, Chicago. Noise Control, Acoustical Society of America, New York. Noise-Symposium, University of Michigan Press, Ann Arbor, 1952. Rosenblith, Walter A., and Kenneth M. Stevens: "Noise and Man," Handbook of Acoustic Noise Control, vol. 11, Technical Report 52204, Wright Air Development Center, Air Research and De velopment Command, United States Air Force, Wright-Patterson Air Force Base, Ohio, June, 1953. The Relation of Hearing Loss to Noise Exposure, Report of Exploratory Committee Z-24-X-2, American Standards Association, New York, 1954. Noise Measurement Beranek, L. L.: Acoustics, McGraw-Hill Book Company, Inc., New York, 1954. ---------- : Acoustic Measurements, John Wilev & Sons, Inc., New York, 1949. Bonvallet, G. L.: "The Measurement of Industrial Noise," American 319 ST0853U0I 320 References Industrial Hygiene Association Quarterly, 13:136-157, Septem ber, 1952. Handbook of Noise Measurement, General Radio Company, Cam bridge, Massachusetts, 1954. Knudsen, V. O., and C. M. Harris: Acoustical Designing in Architec ture, John Wiley & Sons, Inc., New York, 1950. Noise Measurement, Z-24-2, American Standards Association, New York, 1948. Sound Level Meters for Measurement of Noise and Other Sounds, Z-24-3, American Standards Association, New York, 1944. Hearing Cox, I. R., Jr.: "How Quiet Must It Be to Measure Normal Hearing," Noise Control, vol. 1, #1, January, 1955. Davis, H. (Ed.): Hearing and Deafness--A Guide for Laymen, Murrav Hill Books, Inc., New York, 1947. Fletcher, H.: Speech and Hearing in Communication, D. Van Nostrand Company, Inc., New York, 1953. Hirsh, I. ).: The Measurement of Hearing, McGraw-Hill Book Com pany, Inc., New York, 1952. Watson, L. A., and T. Tolan: Hearing Tests and Hearing Instruments, The Williams & Wilkins Company, Baltimore, 1949. ST 0853402 Visual Aids The following films may be'used to supplement much of the material in this book. Both motion pictures and filmstrips are included, the character of each being identified by the self-explanatory abbreviations "MP" and "FS." Immediately following this identification is the name of the primary dis tributor of the film and the year it was produced. Abbrevia tions are identified in the list of sources at the end of the bibliography. In many instances, the films can be borrowed or rented from local or state 16-mm film libraries. A nation wide list of these local sources is given in A Directory of 3300 16mm Film Libraries, available from the Superintendent of Documents, Government Printing Office, Washington 25. Un less otherwise indicated, the motion pictures are 16-mm sound black-and-white films and the filmstrips are 35-mm black-andwhite and silent. The length of the motion pictures is given in minutes (min), that of the filmstrips in frames (fr). For additional films, users should examine the latest an nual editions and supplements of Educational Film Guide and Filmstrip Guide, published by the H. W. Wilson Co., New York 52. The Guides, standard reference books, are available in most school, college, and public libraries. A Clinic on Deafness (MP; Med Film, 1946; 33 min color). Presents the known theories and the physiology of hearing, diagnostic methods to determine hearing range, and medical and surgical therapeutic methods. Prepared by Samuel J. Kopetskv, M.D., and Ralph Almour, M.D. 321 ST 0853403 322 Visual Aids Doctor in Industry (MP; GM, 1946; 60 min). Dramatized photoplay featuring the life and struggles of a young doctor in the pioneer days of industrial medicine. Ears and Hearing (MP; EBF, 1950; 11 min). Describes the physiology of the human ear; portrays how the parts of the ear function; and explains the common causes of impaired hearing. Correlated filmstrip, 70 fr, also available. Fundamentals of Acoustics (MP; EBF, 1952; 11 min). Ex plains velocity of sound, refraction, range of hearing, lower ing intensity, attenuation in air, eliminating high and low frequencies, reverberation and focusing of sound. The Inner Ear (MP; Doho, 1951; 35 min color). Cinemat ographic study of the anatomy, physiology, and pathology of the inner ear. Prepared by H. G. Kobrak, M.D. Recom mended by the American Medical Association for showing to otologists, audiologists, acoustic physicists, physiologists, and experimental psychologists who are interested in problems of hearing. Life Begins Again (MP; West Elec, 1939; 15 min). Shows the dangers of defective hearing, the procedure of a hearing test, and the use of a hearing aid. Explains the purpose of the audiometer testing program. How the Ear Functions (MP; KB, 1940; 11 min). Outlines the structure and function of the human ear; explains the nature of sound waves; and describes the functions of the tympanic membrane, ossicles of ear bones, and other parts of the ear. Medical Aspects of High Intensity Sound (MP series; USN, 1956). Three films describing the nature of noise, psychologic and physiologic hazards of noise, particularly those made bv jet aircraft, acoustic trauma, detection of hearing losses, and the relative effectiveness of ear protection devices. Subtitles and running times of the three films are: General Effects (20 min) Prevention of Hearing Losses (19 min) Ear Defense (21 min) Nose, Throat, and Ears (MP; McGraw, 1947; 10 min). ST 0853404 Visual Aids 323 Shows the functions and structures of the nose, throat, and ears; and recommended procedures for their care. Follow-up filmstrip, 28 fr, also available. Principles of Ultrasonics (MP; BIS, 1955; 15 min). Demon stration of the relation and range of sonic and ultrasonic waves; and the detection, properties, and uses of ultrasonic waves. Quiet Please (MP; Celotex, 1950; 20 min color). Explains the principles of the physics of sound and the methods of controlling noise in all types of buildings. Right to Hear (MP; Iowa, 1942; 31 min color). Demon strates the techniques of group and individual hearing tests, medical follow-up procedures, and educational readjust ments. The Search: Johns Hopkins University: Deafness in Chil dren (MP; YAF, 1955; 25 min). Explains a new approach to the diagnosis and cure of deafness based upon the theory that there is rarely a total loss of hearing. Produced by the Columbia Broadcasting System for television. The Search: University of California at Los Angeles: Noise and Health (MP; YAF, 1956; 25 min). Describes the effect of noise on the health of people. Explains that sound can shatter various substances, and shows how it reacts in a "live" room and a "dead" room. Explains how the problem of noise is be ing combatted. Produced by the Columbia Broadcasting System for television. Sound (MP; EPS, 1939; 9 min). Explains sound waves passing through the air with varying intensities, and the ef fects of vibrations with other objects. Sound Waves (MP; UWF, 1951; 15 min). Establishes the principle that vibrations produce sound waves; analyzes the phenomena of wave motion, wavelength, and frequency; and illustrates the speed of sound in air, in water, and in solids. SoundWaves and Their Sources (MP; EBF, 1950; 10 min). Identifies the three major sources of sound--vibrating col umns of air, vibrating surfaces, and vibrating strings; ex plains the meaning of loudness, pitch, and quality; and shows ST 0853405 324 Visual Aids how the vocal mechanism functions as a vibrating column of air. Submarine Noise Reduction: Bearings, Care in Installa tion (MP; USN, 1955; 19 min). Shows methods used by the U.S. Navy in reducing bearing noise and vibration in the battery vent blower. A specialized film of interest primarily as a method of effecting noise reduction. To Hear Again (MP; USA, 1947; 37 min). Explains and shows examples of the U.S. Army's aural rehabilitation pro gram--testing, treatment, and social rehabilitation; the use of hearing aids and lip reading; and stories of several patients. Primarily for patient orientation. Vibratory Motions and Waves (MP; EPS, 1939; 20 min). Defines and explains damped, undamped, stationary, and propating waves; wavelength, phase, crest, trough, nodes, antinodes, condensation, and rarefaction; and transverse and longitudinal waves. World of Sound (MP; TFC, 1946; 10 min). Explains the importance of sound, the effect of sound waves on the ear drum, and the operation of various types of hearing aids. Produced by Columbia Pictures Corp. You Can Hear Again (MP; USVA, 1949; 30 min). Drama tized story of a veteran who finally recognizes his defective hearing and, through the aural rehabilitation program of the Veterans Administration, learns to compensate for his hear ing difficulty and to lead a normal life. Your Ear and Noise (MP; Acad Opth and Oto, 1950; 12 min color). Describes the relation of problems of noise with the functions of the ear. Shows methods of noise measurement in industry, noise control through ear defender, and noise control procedures. Stresses preemployment and routine pe riodic audiometer tests of emplovees working among hazard ous noise levels. Produced by Howard P. House, M.D., and Douglas Wheeler, Ph.D., for the Subcommittee on Noise in Industry of the Committee of Conservation of Hearing of the Academy of Ophthalmology and Otorhinolaryngology. Visual Aids ST0853406 325 LIST OF FILM SOURCES Acad Opth and Oto--American Academy of Ophthalmology and Otolaryngology, Subcommittee on Noise in Industry, 111 N. Bonnie Brae St., Los Angeles 26 BIS--British Information Services, 30 Rockefeller Plaza, New York 20 Celotex--Celotex Corporation, 120 S. La Salle St., Chicago 3 Doho--Doho Chemical Corporation, 100 Varick St., New York 13 EBF--Encyclopaedia Britannica Films, Inc., 1150 Wilmette Ave., Wilmette, 111. EPS--Edited Pictures System, 165 W. 46th St., New York 19 GM--General Motors Corp., 3044 W. Grand Blvd., Detroit 2, and 405 Montgomery St., San Francisco 4 Iowa U--State University of Iowa, Bureau of Visual Instruc tion, Iowa City, Iowa KB--Knowledge Builders, Floral Park, N. Y. McGraw--McGraw-Hill Book Co., Text-Film Dept., 330 W. 42nd St., New York 36 Med Film--Medical Film Guild, 167 W. 57th St., New York 19 TFC--Teaching Film Custodians, Inc., 25 W. 43rd St., New York 36 USA--U.S. Department of the Army, Washington 25 USN--U.S. Department of the Navy, Washington 25 USVA--U.S. Veterans Administration, Washington 25 UWF--United World Films, Inc., 1445 Park Ave., New York 29 West Elec--Western Electric Co., Motion Picture Bureau, 195 Broadway, New York 7 YAF--Young America Films, Inc., 18 E. 41st St., New York 17 I ST0853401 Index Accrued liability, 53 AudiogTam, initial, 201-202 Acoustic filters, 145-148 Acoustic trauma, 39-41, 303 C5 dip, 40 cumulative character of, 118 interpretation of, 273-278 limitations of, 115 preemployment, 63, 210 recording of, 215-219 handicapping effect of, 257-264 additional information on, 234- Acoustical calibrators, 92, 99, 100 237 "Acoustical Designing in Architec reference level of, 15 ture," 182 Acoustical material, use of, 138-140 reliability of, 200, 202 terminal, 68, 302 Acoustical Society of America, 159 Audiometer, 172 Acoustical zero decibels, 13 calibration of, 194-199 Aerotitis media, 32, 237 checking, 207 Aftertone, 223 description of, 189-193 Alternate loudness balance test, 290 repair of, 198 Ambient noise level, 183-185, 223 selection of, 193-194 American Academy of Ophthalmol what it measures, 180 ogy and Otolaryngology, Sub Audiometric test rooms, types of, committee of, 57, 59, 132, 318 American Medical Association (AMA), hearing loss evaluation, 56 148 planning and building, 158-185 sound levels for, 149 permissible, 155 table of threshold values, 149 American Standards Association, 80, 181, 189, 193 Amplitude, 3 ventilation in, 181-162 Audiometric tests, 285 Audiometry, accuracy of, 181 common errors in, 220-224 of sound waves, 8 continuous sweep frequency, 176 Annoyance due to noise, 45 earphones, testing of, 206 Armed Services, 153 frequency of testing, 300-302 Audiogram, characteristic, 273-278 criteria for referring to physician, inconsistent responses during, 227 instructing subject for, 203, 208, 227, 280-281 220 description of, 187-189 performance of, 204-215 327 ST0853408 328 Index Audiometry, placing earphones for, 209-210 reference level for, 13 responses of subject during, 238, 285 scheduling, 68 screening, 173 seating of subject, 205 self-recording, 173-170 speech, 176-179 training of testers for, 183 when to perform in industry, 242- 248 who should perform, 182-183 Auditory fatigue, 40, 116, 118, 239- 248 duration of, 244-245 recovery curve, 242 relation to permanent loss, 244 in speech range, 241 Auditory rehabilitation, 266-272 Auditory training, 270-272 Average normal hearing as reference level, 13, 192 Compensation for deafness, 52-59 in New York, 52--54 in Wisconsin, 52, 54-59 Conductive deafness, 33-34 Congenital deafness, 35, 278 Conservation of hearing program, 61-74 arranging, 300 benefit to employee, 66 economics of, 62 personnel required, 66 phases of, 68-72 reasons for, 63-65 Consonants, 257-259 Corso, J., 45 Corti, organ of, 21, 25, 20, 172, 250, 290 Criteria, audiometric, for referral to otologist, 227, 280-281 for hearing damage, 122-123 Critical bandwidth, 150 Critical noise level, 113 difficulties in establishing, 115- 119 Basilar membrane, 25 Beranek, L. L., 105, 119, 122, 123, 294, 296 Bilateral hearing loss, 35 Blast trauma, 39 Bone conduction, 7 audiometry, 286-287 Burgess-Manning Co., 158, 162 C5 dip, 40 Cable correction, 100 Calibration, acoustical, correction for, 110 of audiometer, 194-199, 233 of instruments for noise measure ment, 91-92, 99-100 Calibrators, acoustical, *92, 99, 100 Celotex Corporation, 158 Cochlea, 21, 25, 277 fenestration of, 33 Committee of Consultants, New York, 54, 57 Communication in noise, 294 Damage-risk criterion, 119-123 Davis, Ilallowell, 113, 118 Deafness, C5 dip, 40 conductive, 33-34 congenital, 35, 278 cumulative character, 118 definition of, 28 due to noise, 39-41 due to wax, 28, 280 effect on speech, 264 evaluating effects of, 205 functional, 41--42 high-tone, 277 individual reaction to, 260-264 industrial (see Industrial deaf ness) low-tone, 277 in new employees, 201 otosclerosis, 33, 263, 279, 285 perceptive (see Perceptive deaf ness) presbycusis (see Presbycusis) progressive, 37 ST0853409 Index 329 Deafness, unilateral, 37, 264, 287 Decibel, 12-17 addition of, 17, 103 Difference limen testing, 291 Diplacusis, 290 Discrimination loss, 257-259 Discrimination testing for speech, 288-289 Distortion of hearing, 290 Doerfler-Stewart test, 291 Drugs, indiscriminate use of, 37, 280 Ear, anatomy of, 20-25 sensitivity of, 5-6, 12, 18-20 Ear canal, water in, 29 Ear examination, 71, 225-226 forms, 226 Ear histories, 71, 225-232 forms, 228-233 Ear noise, 42-43 Ear protectors, attenuation curves of, 131 distribution of, 134, 306-307 purpose of, 124 selection of, 131-133, 307 types of, 125 Ear wax, impacted, 28, 280 Eardrum, 23, 26, 32 perforated, 29, 31" retracted, 31 ruptured, 31 Earphone cushion attenuation, 152- 154 Earning power, loss of, 52 Effective noise level in test room, 150 Efficiency, effect of noise on, 48-49 Eldredge, D. H., Jr., 118 Eustachian tube, 28-27, 31, 32, 130 Fenestration, 33 Frequency of sound waves, 6, 8 harmonic, 9 fundamental, 9 Functional deafness, 41-42 Cates, R. S., 157 Guild, Stacy R., 118 Hair cells, 25 Hard of hearing, 28 Harmonics, 9 Harris, C., 162 Hazardous noise, 294 Head injuries, 39 Hearing, average normal, 13, 192 definition of, 169-170 relation to speech, 257-259 sensation of, 25 Hearing aids, 268-270 Hearing conservation program, 309- 317 Hearing loss, criteria for, 122-123 determination of handicapping ef fect, 179-180 evaluation of, methods for, 56-59 by AMA, 56 in New York, 57 in Wisconsin, 58 measurement of, 169, 171, 227 minimum measurable, 157 Hearing testing, methods of, 173-180 responsibility for, 70 screening audiometry, 173 selecting room for, 183-187 self-recording audiometry, 173- 176 test material for, 172 Hearing testing survey, when to ob tain, 297 Hereditary perceptive deafness, 37 Hiring personnel with nerve deaf ness, 302-305 History forms, 228-233 House, Howard P., 324 Impacted ear wax, 28, 280 Incus, 23 Individual susceptibility to noise, 69-70 Industrial Acoustics Corp., 158, 162 Industrial deafness, 39-41, 280 handicapping effects of, 257-264 occupations producing, 62 Industrial engineer, 67-68, 78, 132 ST08534I 0 330 Index Industrial physician, responsibility of, 66, 68, 70, 71, 225-227, 273, 280-281, 292-293 Industrial relations, 73-74 Industrial Sound Control Co., 158, 162 Infections, 29-31, 133, 277, 285 Inner ear, 21 Intensity, of common sounds, 16 of sound waves, 8-9 Inverse field, 93 Johns-Manville Co., 158 Kemicterus, 36 Knudsen, V., 182 Kryter, Karl D., 45, 48, 49, 113 Labyrinthosis, 279 Logarithm, definition of, 14 Loudness, of noise, 47 recruitment of, 289-291 of sound, 8-9 Low fence in hearing loss evaluation, 59 McCoy, D. A., 239 Maclile, W., 118 Malingering, 252-255, 280, 291 inconsistent responses, 227 Malleus, 23 Masking, in audiometry, 287 of noise in test room, 149 Maximum safe intensity level, 62, 113 estimates of, 114-118 Measurement, of hearing loss, meth ods of, 169 response mechanism, 171, 227 of sound, in decibels, 12-17 reference level for, 12, 13 Medical Advisory Committee, Wis consin, 57 Medical questionnaire, otological, 227-228 Membrane, basilar, 25 tectorial, 25 Meniere's disease, 37-39, 277, 279, 290 Meningitis, 37 Microbar, 12 Microphone calibration, correction for, 110 Microphones, 82-85 crystal, 82-83 dynamic, 83-84 Microphonics, 102-103 Middle ear, 21 muscles of, 24 Midwest Noise Control Co., 162 Miller, G. A., 45, 46-47 Monaural loudness balance test, 290 Mufflers, 145 Mumps, 37 Nasopharynx, 27, 29, 283 Neural deafness, 34 Nerve deafness, 34 liigh-tone, 277 hiring applicants with, 252 progressive, 37 treatment of, 266-272 unilateral, 37 New York, Committee of Consult ants, 54 compensation legislation in, 52-54 Nodes of standing wave, 11 Noise, annoyance of, 45 classification of, 296 definition of, 10 effects on human lrehavior, 44 efficiency in, 48-49 estimating hazardous nature of, 293-298 individual susceptibility to, 69-70 loudness of, 47 performance in, 48--49 physical measurement of, 69 physiological effect of, 49-50 pitch of, 47 types of, 78-79 white, 286 Noise analyzer, 85-90 reference level for, 13 Noise control, acoustic filters for, 149 harrier, 140 isolation, 142 ST0853U I I Index: 331 Noise control, measures for, 136147 structural modifications for, 143144 Noise and hearing survey, evaluation of, 298-299 plotting of, 112 who should perform, 296-297 Noise level, ambient, 183-185, 223 critical, 113, 115-119 Noise measurement, adding intensi ties for, 103 of background noise, 102 data analysis, 110-112 environmental influences, 104 - equipment for, 79-80 octave bands, checking of, 94 over-all level recheck, 103 recording data for, 105-110 reference level for, 13 sampling location for, 101 sources of error in, 94-95, 101-- 102 types of, 96-97 where to perform, 93 who should make, 78 Noise-measurement instruments, 79-91 acoustical calibrator, 92, 99, 100 calibration of, 92, "93, 99-100 maintenance of, 92, 98-99 meter mechanism, 104--105 microphonics, 102--103 operation of, 97-99 Noise-reduction measures, 72-73 Noise studies, types of, 96-97 Normal average hearing, 13, 192 North American Aviation, Inc., 132, 309 Occupational deafness (see Indus trial deafness) Occupational disease, 52 Occupations causing deafness, 62 Octave-band analyzers, 87-89, 104 checking of, 94 Octaves, 9 <Oscilloscope, cathode-ray, 89, 105, 196 Ossicular chain, 21, 23-24 function of, 26 Otitis media, 29-30, 277 Otological examination, 282-291 history, 71, 282-283 Otologist, referral to, 227, 280-281 responsibilities of, 70-71, 227228, 254, 273, 307-308 Otosclerosis, 33, 279, 285 psychological effects of, 263 Outer ear, 21 Oval window, 24 Fain in ears as criterion for deafness, 122 Parrack, H. O., 118 Pars flaccida, 29 Perceptive deafness, 33-34 progressive, 279 treatment for, 266-272 Perforated eardrum, 29 Performance and efficiency, effect of noise on, 48-49 P; ermanent deafness, 53-54 Phonetically balanced words, 179 1Physiologic effects of noise, 49-50 Pitch, 8-9 'Plant survey, 92-93 ]Plenum chamber, 145 1Preemployment audiometry, 63, 201-202, 224, 253, 300 ]Prefabricated test rooms, 158, 162- 165, 186 P1 replacement audiometry, 55, 202, 224 1Presbycusis, 34-35, 248-252, 259, 262, 277, 279 allowance for, in disability table, 59 curves, 249, 251 handicapping effect of, 262-263 premature, 305 relation to industrial deafness, 250 Preventive medicine, value of audio metric testing in, 64 Progressive nerve deafness, 37 .1 ST0853Ul2 332 Index Psychogalvanic skin resistance test, 291 Psychogenic deafness, 42, 280 Psychological effects of deafness, 256-205 Pure tone, 7 advantages in hearing testing, 172 Records, of audiograms, 215-219, 234-237 of audiometric testers, 233-234 of ear examinations, 225-228 of ear histories, 228-233 information on audiogram, 234-- 237 . of noise measurement, 105-110 Recorders, use of, in noise measure ment, 90 Recovery curve plotted, 242 Recruitment of loudness, 289-291 Rehabilitation, auditory, 268-272 Reference level, 12, 13, 191 Repeated impact noises, 79 Residual hearing, use of, 270--272 Response, inconsistent, 227, 285 mechanics of, 171 Retracted eardrum, 31 Reverberant field, 93, 111 Reverberation, 139 RH incompatibility, 38 Rinne's test, 284 Rosenblith, Walter A., 45, 119, 122, 123 Round window, 24 Ruptured eardrum, 31 Safety engineer, 66, 67-68, 132 Scala media, 25 Schwabach's test, 284 Screening audiometry, 173 Screening plant survey, 96 Self-recording audiometry, 173-176 audiogram for, 218-^219 Sensitivity, of human ear, 5-6, 12, 18-20 of nerve-deafened ears, 303 Serial audiogram, 216 Shadow curve, 287 Shock absorbers, 144 Single impact noise, 79 Sound, generation of, 137 Sound barriers, 140-142 Sound fields, 93 Sound-level meter, 80-85, 101, 104- 105, 184 microphones, 82-85 reference level for, 13 Sound measurement (see Measure ment) Sound survey, communication dur ing, 110 Sound-survey meter, 79-80 Sound waves, amplitude of, 8 characteristics of, 6-11 definition of, 3-5 frequency of, 8 intensity of, 8 length of, 11 medium of transmission, 6 pure tone, 7-8 speed of, 7 standing, 10-11, 222 ultrasonic, 6 Speech, effect of deafness on, 264 Speech audiometry, 176-179 Speech discrimination testing, 179, 288-289 Speech interference level, 295 Speech reading, 272 Speech-reception threshold, 178, 287-288 Speed of sound, 7 Spondee words, 178, 288 Standing sound wave, 10-11, 222 Stapes, 23 mobilization of, 33 Steady narrowband noise, 79 Steady wideband noise, 78-79 Sterner, J., 114 Structural modifications for noise abatement, 143--144 Subcommittee on Noise, 57, 59, 132, 318 Susceptibility to noise, 69, 118 tests, 244-245 Sweep-frequency audiogram, 219 RECEIVED library ST 085341 3