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Consensus Development Conference Statement January 22-24, 1990
This statement is more than five years old and is provided solely for historical purposes. Due to the cumulative nature of medical research, new knowledge has inevitably accumulated in this subject area in the time since the statement was initially prepared. Thus some of the material is likely to be out of date, and at worst simply wrong. For reliable, current information on this and other health topics, we recommend consulting the National Institutes of Health's MedlinePlus http://www.nlm.nih.gov/medlineplus/. This statement was originally published as: Noise and Hearing Loss. NIH Consens Statement 1990 Jan 22-24;8(1):1-24. For making bibliographic reference to the statement in the electronic form displayed here, it is recommended that the following format be used: Noise and Hearing Loss. NIH Consens Statement Online 1990 Jan 22-24 [cited year month day];8(1):1-24.AbstractThe National Institutes of Health Consensus Development Conference on Noise and Hearing Loss brought together biomedical and behavioral scientists, health care providers, and the public to address the characteristics of noise-induced hearing loss, acoustic parameters of hazardous noise exposure, individual and age-specific susceptibility, and prevention strategies. Following a day and a half of presentations by experts and discussion by the audience, a consensus panel weighed the evidence and prepared a consensus statement. Among their findings, the panel concluded that sounds of sufficient intensity and duration will damage the ear and result in temporary or permanent hearing loss at any age. Sound levels of less than 75 dB(A) are unlikely to cause permanent hearing loss, while sound levels about 85 dB(A) with exposures of 8 hours per day will produce permanent hearing loss after many years. Current scientific knowledge is inadequate to predict that any particular individual will be safe when exposed to a hazardous noise. Strategies to prevent damage from sound exposure should include the use of individual hearing protection devices, education programs beginning with school-age children, consumer guidance, increased product noise labeling, and hearing conservation programs for occupational settings. The full text of the consensus panel's statement follows. IntroductionHearing loss afflicts approximately 28 million people in the United States. Approximately 10 million of these impairments are at least partially attributable to damage from exposure to loud sounds. Sounds that are sufficiently loud to damage sensitive inner ear structures can produce hearing loss that is not reversible by any presently available medical or surgical treatment. Hearing impairment associated with noise exposure can occur at any age, including early infancy, and is often characterized by difficulty in understanding speech and the potentially troublesome symptom, tinnitus (i.e., ringing in the ears). Very loud sounds of short duration, such as an explosion or gunfire, can produce immediate, severe, and permanent loss of hearing. Longer exposure to less intense but still hazardous sounds, commonly encountered in the workplace or in certain leisure time activities, exacts a gradual toll on hearing sensitivity, initially without the victim's awareness. More than 20 million Americans are exposed on a regular basis to hazardous noise levels that could result in hearing loss. Occupational noise exposure, the most common cause of noise-induced hearing loss (NIHL), threatens the hearing of firefighters, police officers, military personnel, construction and factory workers, musicians, farmers, and truck drivers, to name a few. Live or recorded high-volume music, recreational vehicles, airplanes, lawn-care equipment, woodworking tools, some household appliances, and chain saws are examples of nonoccupational sources of potentially hazardous noise. One important feature of NIHL is that it is preventable in all but certain cases of accidental exposure. Legislation and regulations have been enacted that spell out guidelines for protecting workers from hazardous noise levels in the workplace and consumers from hazardous noise during leisure time pursuits. Inconsistent compliance and spotty enforcement of existing governmental regulations have been the underlying cause for their relative ineffectiveness in achieving prevention of NIHL. A particularly unfortunate occurrence was the elimination of the Office of Noise Abatement and Control within the Environmental Protection Agency in 1982. On January 22-24, 1990, the National Institute on Deafness and Other Communication Disorders, together with the Office of Medical Applications of Research of the National Institutes of Health, convened a Consensus Development Conference on Noise and Hearing Loss. Cosponsors of the conference were the National Institute of Child Health and Human Development, the National Institute on Aging, and the National Institute for Occupational Safety and Health of the Centers for Disease Control. The effects of environmental sounds on human listeners may include:
This conference was entirely centered on NIHL. The panel focused on five questions related to noise and hearing loss:
Following a day and a half of presentations
by experts in the relevant fields and discussion from the audience, a
consensus panel comprising specialists and generalists from the medical
and other related scientific disciplines, together with public
representatives, considered the evidence and formulated a consensus
statement in response to the five previously stated questions. What is Noise-Induced Hearing Loss?Sounds of sufficient intensity and duration will damage the ear and result in temporary or permanent hearing loss. The hearing loss may range from mild to profound and may also result in tinnitus. The effect of repeated sound overstimulation is cumulative over a lifetime and is not currently treatable. Hearing impairment has a major impact on one's communication ability and even mild impairment may adversely affect the quality of life. Unfortunately, although NIHL is preventable, our increasingly noisy environment places more and more people at risk. Studies of NIHLMost studies of the association between sound exposure and hearing loss in humans are retrospective measurements of the hearing sensitivities of numerous individuals correlated with their noise exposures. The variability within these studies is usually large; thus, it is difficult to predict the precise magnitude of hearing loss that will result from a specific sound exposure. Prospective studies of selected workers' hearing levels over a long time while their sound exposures are carefully monitored are costly and time-consuming and, due to attrition, require a large number of subjects. When significant hearing loss is found, for ethical reasons, exposures must be reduced, interfering with the relationships under study. Although studies of NIHL in humans are difficult, they provide valuable information not available from animal studies and should be continued. In prospective animal studies, sound exposures can be carefully controlled, and the anatomic and physiologic correlates of NIHL can be precisely defined. Although there may be interspecies differences with respect to the absolute sound exposure that will injure the ear, the basic mechanisms that lead to damage appear to be similar in all mammalian ears. Anatomic and Physiologic Correlates of NIHLTwo types of injury are recognized: acoustic trauma and NIHL. Short-duration sound of sufficient intensity (e.g., a gunshot or explosion) may result in an immediate, severe, and permanent hearing loss, which is termed acoustic trauma. Virtually all of the structures of the ear can be damaged, in particular the organ of Corti, the delicate sensory structure of the auditory portion of the inner ear (cochlea), which may be torn apart. Moderate exposure may initially cause temporary hearing loss, termed temporary threshold shift (TTS). Structural changes associated with TTS have not been fully established but may include subtle intracellular changes in the sensory cells (hair cells) and swelling of the auditory nerve endings. Other potentially reversible effects include vascular changes, metabolic exhaustion, and chemical changes within the hair cells. There is also evidence of a regional decrease in the stiffness of the stereocilia (the hair bundles at the top of the hair cells), which may recover. This decrease in stereocilia stiffness may lead to a decrease in the coupling of sound energy to the hair cells, which thereby alters hearing sensitivity. Repeated exposure to sounds that cause TTS may gradually cause permanent NIHL in experimental animals. In this type of injury, cochlear blood flow may be impaired, and a few scattered hair cells are damaged with each exposure. With continued exposure, the number of damaged hair cells increases. Although most structures in the inner ear can be harmed by excessive sound exposure, the sensory cells are the most vulnerable. Damage to the stereocilia is often the first change, specifically, alteration of the rootlet structures that normally anchor the stereocilia into the top of the hair cell. Once destroyed, the sensory cells are not replaced. During the recovery period between some sound exposures, damaged regions of the organ of Corti heal by scar formation. This process is very important because it reestablishes the barrier between the two fluids of the inner ear (perilymph and endolymph). If this barrier is not reestablished, degeneration of hair cells may continue. Further, once a sufficient number of hair cells are lost, the nerve fibers to that region also degenerate. With degeneration of the cochlear nerve fibers, there is corresponding degeneration within the central nervous system. The extent to which these neural changes contribute to NIHL is not clear. With moderate periods of exposure to potentially hazardous high-frequency sound, the damage is usually confined to a restricted area in the high-frequency region of the cochlea. With a comparable exposure to low-frequency noise, hair cell damage is not confined to the low-frequency region but may also affect the high-frequency regions. The predominance of damage in different cochlear regions with different frequency exposures reflects factors such as the resonance of the ear canal, the middle-ear transfer characteristics, and the mechanical characteristics of the organ of Corti and basilar membrane. Assessment of NIHLHearing loss is measured by determining auditory thresholds (sensitivity) at various frequencies (pure-tone audiometry). Complete assessment should also include measures of speech understanding and middle-ear status (immittance audiometry). Pure-tone audiometry is also used in industrial hearing conservation programs to determine whether adequate protection against hazardous sound levels is provided. The first audiometric sign of NIHL resulting from broadband noise is usually a loss of sensitivity in the higher frequencies from 3,000 through 6,000 Hertz (Hz) (i.e., cycles per second), resulting in a characteristic audiometric "notch." With additional hearing loss from noise or aging, the threshold at 8,000 Hz may worsen and eliminate this characteristic audiometric pattern. Thus, the presence or absence of NIHL cannot be established on the basis of audiometric shape, per se. The hearing loss is usually bilateral, but some degree of asymmetry is not unusual, especially with lateralized noise sources such as rifles. After moderate sound exposure, TTS may occur, and, during a period of relative quiet, thresholds will return to normal levels. If the exposure continues on a regular basis, permanent threshold shifts (PTS) will result, increasing in magnitude and extending to lower and higher frequencies. If the exposures continue, NIHL increases, more rapidly in the early years. After many years of exposure, NIHL levels off in the high frequencies, but continues to worsen in the low frequencies. Although TTS and PTS are correlated, the relation is not strong enough to use TTS to predict the magnitude of permanent hearing loss. An important consequence of the sensitivity loss associated with NIHL is difficulty in understanding speech. Whereas a large proportion of the energy in speech is contained within the low-frequency range, much of the information required to differentiate one speech sound from another is contained within the higher frequencies. With significant hearing loss in the high frequencies, important speech information is often inaudible or unusable. Other interfering sounds such as background noise, competing voices, or room reverberation may reduce even further the hearing-impaired listener's receptive communication ability. The presence of tinnitus may be an additional debilitating condition. NIHL may interfere with daily life, especially those social activities that occur in noisy settings. Increased effort is required for understanding speech in these situations, which leads to fatigue, anxiety, and stress. Decreased participation in these activities often results, affecting not only hearing-impaired individuals but also friends and family members. Hearing loss is associated with depression in the elderly and may be related to dementia and cognitive dysfunction. Systematic study of the effects of hearing loss on the quality of life have only lately focused specifically on individuals with NIHL; therefore, continued studies of this kind are desirable. The impairment in hearing ability resulting
from NIHL may vary from mild to severe. An individual's ability to
communicate and function in daily life varies with the degree of loss and
the individual's communication needs although these relationships are
complex. The magnitude of the effect on communication ability may be
estimated by a variety of scales, which are often used in disability
determinations. These scales, which vary substantially in the frequencies
used, the upper and lower limits of impairment, age correction, and
adjustment for asymmetric hearing loss, attempt to predict the degree of
communication impairment (understanding of speech) on the basis of
pure-tone thresholds. There is no consensus about the validity or utility
of the scales, which scale should be used, whether measures of speech
understanding should be included, or whether self-assessment ratings
should be incorporated into either impairment rating scales or disability
determinations. What Sounds Can Damage Hearing?Some sounds are so weak physically that they are not heard. Some sounds are audible but do not have any temporary or permanent after-effects. Some sounds are strong enough to produce a temporary hearing loss from which there may appear to be complete recovery. Damaging sounds are those that are sufficiently strong, sufficiently long-lasting, and involve appropriate frequencies so that permanent hearing loss will ensue. Most of the sounds in the environment that produce such permanent effects occur over a very long time (for example, about 8 hours per workday over a period of 10 or more years). On the other hand, there are some particularly abrupt or explosive sounds that can cause damage even with a single exposure. The line between these categories of sounds cannot be stated simply because not all persons respond to sound in the same manner. Thus, if a sound of given frequency bandwidth, level, and duration is considered hazardous, one must specify for what proportion of the population it will be hazardous and, within that proportion, by what criterion of damage (whether anatomical, audiometric, speech understanding) it is hazardous. The most widely used measure of a sound's strength or amplitude is called "sound level," measured by a sound-level meter in units called "decibels" (dB). For example, the sound level of speech at typical conversational distances is between 65 and 70 dB. There are weaker sounds, still audible, and of course much stronger sounds. Those above 85 dB are potentially hazardous. Sounds must also be specified in terms of frequency or bandwidth, roughly like the span of keys on a piano. The range of audible frequencies extends from about 20 Hz, below the lowest notes on a piano, to at least 16,000 or 20,000 Hz, well above the highest notes on a piccolo. Most environmental noises include a wide band of frequencies and, by convention, are measured through the "A" filter in the sound-level meter and thus are designated in dB(A) units. It is not clear what effect, if any, sound outside the frequency range covered in dB(A) measurements may have on hearing. At this time, it is not known whether ultrasonic vibration will damage hearing. To define what sounds can damage hearing, sound level, whether across all frequency bands or taken band by band, is not enough. The duration of exposure--typical for a day and accumulated over many years--is critical. Sound levels associated with particular sources such as snowmobiles, rock music, and chain saws, are often cited, but predicting the likelihood of NIHL from such sources also requires knowledge of typical durations and the number of exposures. There appears to be reasonable agreement that sound levels below 75 dB(A) will not engender a permanent hearing loss, even at 4000 Hz. At higher levels, the amount of hearing loss is directly related to sound level for comparable durations. According to some existing rules and regulations, a noise level of 85 dB(A) for an 8-hour daily exposure is potentially damaging. If total sound energy were the important predictor, an equivalent exposure could be as high as 88 dB(A) if restricted to 4 hours. (A 3-dB increase is equivalent to doubling the sound intensity.) This relation, enshrined in some standards and regulations, is a theory based on a dose or exposure defined by total energy. In spite of the physical simplicity of a total-energy concept, other principles have been invoked to define equivalent exposures of different sound levels and durations. Early research suggested that NIHL after 10 years could be predicted from temporary threshold shifts (TTS) measured 2 minutes after a comparable single-day exposure. Those results, however, were taken to indicate that a halving of duration could be offset by a 5-dB change in sound level rather than a 3-dB change. This 5-dB rule is implemented in the Walsh-Healey Act of 1969 and subsequent Occupational Safety and Health Administration regulations for the purpose of requiring preventive efforts for noise-exposed workers. The 3-dB trading rule is agreed to in International Standards Organization (ISO) Standard 1999.2 (1989) for the purpose of predicting the amount of noise-induced hearing loss resulting from different exposures. There is no consensus concerning a single rule to be used for all purposes in the United States. Generally, for sound levels below about 140 dB, different temporal forms of sound, whether impulse (gunshot), impact (drop forge) or steady state (turbine), when specified with respect to their level and duration, produce the same hearing loss. This does not appear to follow at levels above 140 dB, where impulse noise creates more damage than would be predicted. This may imply that impulse noise above a certain critical level results in acoustic trauma from which the ear cannot recover. Although sound exposures that are potentially hazardous to hearing are usually defined in terms of sound level, frequency bandwidths, and duration, there are several simple approximations that indicate that a sound exposure may be suspected as hazardous. These include the following: If the sound is appreciably louder than conversational level, it is potentially harmful, provided that the sound is present for a sufficient period of time. Hazardous noise may also be suspected if the listener experiences: (a) difficulty in communication while in the sound, (b) ringing in the ear (tinnitus) after exposure to the sound, and/or (c) the experience that sounds seem muffled after leaving the sound-exposure area. In the consideration of sounds that can
damage hearing, one point is clear: it is the acoustic energy of the sound
reaching the ear, not its source, which is important. That is, it does not
matter if the hazardous sound is generated by a machine in the workplace,
by an amplifier/loudspeaker at a rock concert, or by a snowmobile ridden
by the listener. Significant amounts of acoustic energy reaching the ear
will create damage--at work, at school, at home, or during leisure
activities. Although there has been a tendency to concentrate on the more
significant occupational and transportation noise, the same rules apply to
all potential noise hazards. What Factors, Including Age, Determine an Individual's Susceptibility to Noise-Induced Hearing Loss?One thoroughly established characteristic of NIHL is that, on the average, more intense and longer-duration noise exposures cause more severe hearing loss. A second is that there is a remarkably broad range of individual differences in sensitivity to any given noise exposure. Several factors have been proposed to explain differences in NIHL among individuals; others may be associated with differences over time within the same individual. It is important to distinguish those factors whose roles in determining susceptibility are supported by a consistent body of theory and empirical evidence from other factors whose roles have been proposed but for which theory, data, or both are less conclusive. Differences Among IndividualsBoth temporary threshold shift (TTS) and permanent threshold shift (PTS) in response to a given intense noise may differ as much as 30 to 50 dB among individuals. Both animal research and retrospective studies of humans exposed to industrial noise have demonstrated this remarkable variation in susceptibility. The biological bases for these differences are unknown. A number of extrinsic factors (e.g., characteristics of the ear canal and middle ear, drugs, and prior exposure to noise) may influence an individual's susceptibility to NIHL. However, animal studies that have controlled these variables suggest that individual differences in inner ear anatomy and physiology also may be significant. Additional research is necessary to determine whether vascular, neural feedback (efferent system), or other mechanisms can account for and predict such individual variation. One factor that may be associated with decreased susceptibility to NIHL is conductive hearing loss; the cochlear structures may be protected by any form of acoustic attenuation. For similar reasons, middle ear muscles, which normally serve a protective function by contracting in response to intense sound, when inoperative, can result in increased susceptibility. Among the other factors that are theoretically associated with differences in susceptibility are (a) unusually efficient acoustic transfer through the external and middle ear, as a determinant of the amount of energy coupled to the inner ear structures, and (b) preexisting hearing loss, which could imply that less additional loss would occur if the sensitive structures have already been damaged. Support for these hypotheses has been modest, in the case of the transfer function, because little empirical work has been done to test that hypothesis, and, in the case of reduced sensitivity, because several studies disagree. In general, when there is a difference in average loss to a given noise exposure, those ears with previous PTS or TTS have shown somewhat less additional loss than those not previously exposed. Findings have sometimes implicated degree of pigmentation, both of the receptor structures (melanization) and of the eye and skin, as related to susceptibility. However, these results too are equivocal. GenderThere is little difference in hearing thresholds between young male and female children. Between ages 10 and 20, males begin to show reduced high-frequency auditory sensitivity relative to females. Women continue to demonstrate better hearing than men into advanced age. These gender differences are probably due to greater exposure of males to noise rather than to their inherent susceptibility to its effects. Differences Within IndividualsOtotoxic drugsAmong the causes of differences of susceptibility to noise exposure within individuals are ototoxic drugs and other chemicals. In animal research, certain antibiotics (aminoglycosides) appear to exacerbate the damaging effects of noise exposure. Clinical evidence of corresponding effects in human patients has not been established, but precautions should be taken with regard to noise exposures of individual patients treated with these medications. Although high doses of aspirin are widely known to cause TTS and tinnitus, aspirin has not been shown to increase susceptibility to NIHL. AgeIn certain animal models there is evidence of heightened susceptibility to noise exposure shortly after birth--a "critical period" (possibly following the time when fluids fill the middle ear but before complete development of the cochlear structures). However, it is not clear that data from such animal models can be generalized to full-term normal human infants. Premature infants in noisy environments (e.g. neonatal intensive care units), however, may be at risk At the other extreme, increasing age has been hypothesized to be associated with decreasing susceptibility. This contention is based on the existence of presbycusis, hearing loss that increases with age and that is not known to be attributable to excessive noise exposure or other known etiology. The typical levels of presbycusis at various ages have recently been incorporated as Annex A in International Standards Organization Standard 1999.2 (1989). That standard may be used to estimate the portion of overall hearing loss that is attributable to exposure to excessive noise. In summary, scientific knowledge is
currently inadequate to predict that any individual will be safe in noise
that exceeds established damage-risk criteria, nor that specific
individuals will show greater-than-average loss following a given
exposure. Among the many proposed explanations, the hypothesis that the
resonant and transmission properties of the external and middle ear affect
individual susceptibility deserves further attention. Empirical support
for this hypothesis should not be difficult to obtain, but very few data
have been collected on this question, both for TTS (experimentally) and
PTS (retrospectively). Differences in susceptibility of the cochlear
structures to NIHL may exist, but no practical approach to predicting them
is yet available. Identification of susceptible humans will almost
certainly be delayed until a successful animal model is available. What Can Be Done To Prevent Noise-Induced Hearing Loss?Noise-induced hearing loss occurs every day--in both occupational and nonoccupational settings. The crucial questions for prevention are as follows: (1) What can individuals do to protect themselves from NIHL? (2) What role should others, such as educators, employers, or the Government, play in preventing NIHL? (3) What general strategies should be employed to prevent NIHL? Answers to these questions have long been known, but solutions have not been effectively implemented in many cases. As a result, many people have needlessly suffered hearing loss. Individual Protection StrategiesHearing conservation must begin by providing each individual with basic information. NIHL is insidious, permanent, and irreparable, causing communication interference that can substantially affect the quality of life. Ringing in the ears and muffling of sounds after sound exposure are indicators of potential hazard. Dangerous sound exposures can cause significant damage without pain, and hearing aids do not restore normal hearing. Individuals should become aware of loud noise situations and avoid them if possible or properly use hearing protection. It is important to recognize that both the level of the noise and its duration (i.e., exposure) contribute to the overall risk. Certain noises, such as explosions, may cause immediate permanent damage. Many sources, such as guns, power tools, chain saws, small airplanes, farm vehicles, firecrackers, some types of toys, and some medical and dental instruments may produce dangerous exposures. Music concerts, car and motorcycle races, and other spectator events often produce sound levels that warrant hearing protection. Similarly, some stereo headphones and loudspeakers are capable of producing hazardous exposures. Parents should exercise special care in supervising the use of personal headset listening devices, and adults and children alike should learn to operate them at safe volume settings. Nonoccupational StrategiesHearing loss from nonoccupational noise is common, but public awareness of the hazard is low. Educational programs should be targeted toward children, parents, hobby groups, public role models, and professionals in influential positions such as teachers, physicians, audiologists and other health care professionals, engineers, architects, and legislators. In particular, primary health care physicians and educators who deal with young people should be targeted through their professional organizations. Consumers need guidance and product noise labeling to assist them in purchasing quieter devices and in implementing exposure reduction strategies. The public should be made aware of the availability of affordable, effective hearing protectors (ear plugs, ear muffs, and canal caps). Hearing protection manufacturers should supply comprehensive instructions concerning proper protector use and also be encouraged to increase device availability to the public sector. Newborn nurseries, including neonatal intensive care units, should be made quieter. Medical and dental personnel should be trained to educate their patients about NIHL. Individuals with significant noise exposure need counseling. Basic audiometric evaluations should be widely available. The goal is to detect early noise-induced damage and interrupt its progression before hearing thresholds exceed the normal range. Occupational StrategiesHearing conservation programs for occupational settings must include the following interactive components: sound surveys to assess the degree of hazardous noise exposure, engineering and administrative noise controls to reduce exposures, education to inform at-risk individuals why and how to prevent hearing loss, hearing protection devices (earplugs, earmuffs, and canal caps) to reduce the sound reaching the ear, and audiometric evaluations to detect hearing changes. Governmental regulations that currently apply to most noisy industries should be revised to encompass all industries and all employees, strengthened in certain requirements, and strictly enforced with more inspections and more severe penalties for violations. Many existing hearing conservation programs remain ineffective due to poor organization and inadequately trained program staff. Senior management must use available noise controls, purchase quieter equipment, and incorporate noise reduction in planning new facilities. Noise exposures must be measured accurately and the degree of hazard communicated to employees. Hearing protection devices must be available that are comfortable, practical for the demands of work tasks, and provide adequate attenuation. Labeled ratings of hearing protector attenuation must be more realistic so that the degree of protection achieved in the workplace can be properly estimated. Each employee must be individually fitted with protectors and trained in their correct use and care. Employees need feedback about their audiometric monitoring results annually. Employers need to monitor program effectiveness by using appropriate techniques for analysis of group audiometric data. By detecting problem areas, managers can prioritize resource allocations and modify company policies to achieve effectiveness. Potential benefits include reduced costs for worker's compensation, enhanced worker morale, reduced absenteeism, fewer accidents, and greater productivity. Enactment of uniform regulations for awarding worker's compensation for occupational hearing loss would stimulate employers' interest in achieving effective hearing conservation programs. Equitable criteria for compensability should be developed based on scientific investigations of the difficulties in communication and other aspects of auditory function encountered in everyday life by persons with differing degrees of NIHL. General StrategiesBoth nonoccupational and occupational NIHL
could be reduced by implementing broader preventive efforts. Labeling of
consumer product noise emission levels should be enforced according to
existing regulations. Incentives for manufacturers to design quieter
industrial equipment and consumer goods are needed along with regulations
governing the maximum emission levels of certain consumer products, such
as power tools. Reestablishment of a Federal agency coordinating committee
with central responsibility for practical solutions to noise issues is
essential. Model community ordinances could promote local planning to
control environmental noise and, where feasible, noise levels at certain
spectator events. High-visibility media campaigns are needed to develop
public awareness of the effects of noise on hearing and the means for
self-protection. Prevention of NIHL should be part of the health curricula
in elementary through high schools. Self-education materials for adults
should be readily available. What Are the Directions for Future Research?The panel recommends that research be undertaken in two broad categories: (1) Studies that use existing knowledge to prevent NIHL in the immediate future, and (2) research on basic mechanisms to prevent NIHL in the long-term future.
Conclusions and Recommendations
Consensus Development Panel
Conference and Panel Chairperson Director Boys Town National Research Hospital Professor and Chair Department of Otolaryngology Creighton University Omaha, Nebraska
Director Auditory Systems Laboratory Department of Industrial Engineering and Operations Research Virginia Polytechnic Institute and State University Blacksburg, Virginia
Professor Department of Otolaryngology and Communicative Sciences Baylor College of Medicine Houston, Texas
Professor Department of Psychology University of Maryland Baltimore County Catonsville, Maryland
Associate Professor of Surgery Division of Head and Neck Surgery University of California at Los Angeles School of Medicine Los Angeles, California
Professor and Vice Chairman Department of Otolaryngology Washington University St. Louis, Missouri
Professor Department of Psychology Washington University Director of Research Emeritus Central Institute for the Deaf St. Louis, Missouri
Associate Professor in Residence Department of Otolaryngology Coleman-Epstein Laboratories University of California San Francisco, California
Assistant Professor of Clinical Pediatrics Washington University Medical School/Northwest Pediatrics Florissant, Missouri
President Environmental Noise Consultants, Inc. Cary, North Carolina
Assistant Professor of Epidemiology Department of Epidemiology University of Pittsburgh Graduate School of Public Health Pittsburgh, Pennsylvania
Attorney/Professor of Law Arizona State University College of Law Tempe, Arizona
Professor and Chair Department of Speech and Hearing Sciences Speech and Hearing Center Indiana University Bloomington, Indiana
Professor Department of Audiology and Hearing Impairment Northwestern University Evanston, Illinois Speakers
"Clinical Criteria: Noise or Not?" Professor and Chairman Department of Otolaryngology University of Toronto Toronto, Ontario CANADA
"Noise Exposure in Adolescents and Young Adults" Professor Department of Audiology University of Goteborg Roda Straket Goteborg SWEDEN
"Hearing Protection--the State of the Art (Circa 1990) and Research Priorities for the Coming Decade" Manager Acoustical Engineering E-A-R Division Indianapolis, Indiana
"Patterns of Cellular Degeneration in the Inner Ear Following Excessive Exposure to Noise" Department of Otolaryngology Washington University School of Medicine St. Louis, Missouri
"Noise Exposure and Hearing Loss From Leisure Activities" Director Graduate Program in Communication Sciences Central Institute for the Deaf St. Louis, Missouri
"Effects of Noise-Induced Hearing Loss on Quality of Life" Professor Head and Neck Surgery Department of Otolaryngology Director Bloedel Hearing Research Center University of Washington Seattle, Washington
"Prevention Strategies: Education" Professor Communication Research Laboratory Northeastern University Boston, Massachusetts
"Prenatal and Perinatal Risks" Associate Professor and Chair Department of Communication Processes and Disorders University of Florida Gainesville, Florida
"Acoustic Parameters of Hazardous Noise Exposures" Professor and Chairman Communicative Disorders and Sciences State University of New York at Buffalo Buffalo, New York
"Individual Susceptibility--Nonauditory Factors" Professor Department of Speech and Hearing Sciences Indiana University Bloomington, Indiana
"Biological Bases of Acoustic Injury" Associate Professor of Physiology and Otolaryngology Harvard Medical School Eaton-Peabody Laboratory Massachusetts Eye and Ear Infirmary Boston, Massachusetts
"Noise and the Aging Process" Professor Department of Otolaryngology Medical University of South Carolina Charleston, South Carolina
"Interactions Between Hearing Loss and the Environment" Research Professor Audiology and Speech Pathology Department University of Tennessee Knoxville, Tennessee
"Evaluation of Disability and Handicap" Professor Department of Psychology The University of New England Armidale, New South Wales AUSTRALIA
"The Effects of Certain Auditory Factors on Individual Susceptibility to Noise" Central Institute for the Deaf St. Louis, Missouri
"Critical Periods and Acoustic Trauma" Associate Professor Department of Speech Pathology and Audiology James Madison University Harrisonburg, Virginia
"Interaction Between Noise and Other Agents" Professor Communicative Disorders and Sciences Hearing Research Laboratory State University of New York at Buffalo Buffalo, New York
"The Measurement of Noise Exposure and the Assessment of Risk" Research Emeritus Division of Physics National Research Council Ottawa, Ontario CANADA
"Noise Reduction to Prevent Hearing Damage--State of the Art, Implementation Problems, and Future Directions" Consultant in Acoustics and Noise Control Stewart Acoustical Consultants Raleigh, North Carolina
"The Noise-Induced Hearing Loss Problem" Director Emeritus Biodynamics and Bioengineering Division Armstrong Aerospace Medical Research Laboratory Clinical Professor Wright State University School of Medicine Yellow Springs, Ohio
"Impulse/Impact vs. Continuous Noise" Professor Department of Communication Disorders University of Minnesota Minneapolis, Minnesota Planning Committee
Planning Committee Chairperson Director Extramural Program Division of Communication Sciences and Disorders National Institute on Deafness and Other Communication Disorders National Institutes of Health Bethesda, Maryland
Conference and Panel Chairperson Director Boys Town National Research Hospital Professor and Chair Department of Otolaryngology Creighton University Omaha, Nebraska
Director Graduate Program in Communication Sciences Central Institute for the Deaf St. Louis, Missouri
Program Analyst Office of Medical Applications of Research National Institutes of Health Bethesda, Maryland
Director Office of Medical Applications of Research National Institutes of Health Bethesda, Maryland
Director of Communications Office of Medical Applications of Research National Institutes of Health Bethesda, Maryland
Professor and Chairman Communicative Disorders and Sciences State University of New York at Buffalo Buffalo, New York
Information Coordinator National Institute on Deafness and Other Communication Disorders National Institutes of Health Bethesda, Maryland
Associate Director Center for Research for Mothers and Children National Institute of Child Health and Human Development National Institutes of Health Bethesda, Maryland
Professor Department of Otolaryngology University Hospital Clinics Ohio State University Columbus, Ohio
Chief Neurobiology and Neuropsychology Units Neuroscience and Neuropsychology of Aging Program National Institute on Aging National Institutes of Health Bethesda, Maryland
Assistant Director Army Audiology and Speech Center Walter Reed Army Medical Center Washington, D.C.
Deputy Director Division of Communication Sciences and Disorders National Institute on Deafness and Other Communication Disorders National Institutes of Health Bethesda, Maryland
Conference Coordinator Prospect Associates Rockville, Maryland
Visiting Scientist National Institute on Occupational Safety and Health Centers for Disease Control Cincinnati, Ohio
Conference Coordinator Prospect Associates Rockville, Maryland Conference Sponsors
Jay Moskowitz, Ph.D. Acting Director
John H. Ferguson, M.D. Director
Duane F. Alexander, M.D. Director
T. Franklin Williams, M.D. Director
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