However, to develop some logic in controlling noise exposure, we have to look at the impact or the effects of it. What I would like to do is read into the record something from our statement that has to do with the people who may be affected by noise in the population at risk. When we developed the criteria document, we figured there were 21⁄2 million industrial workers who were potentially exposed to hazardous noise levels. These were the workers covered by the Occupational Safety and Health Act. But, in addition to those, there are about 41⁄2 million transportation workers, about 31⁄2 million construction workers, over 600,000 miners and 4.7 million agricultural workers plus all of the Government employees, people employed by the Federal, State, and local governments. Some of our concern in this area of noise and noise exposure has to do with some of the methods that you might use to monitor hearing loss. Measurement of hearing ability is very complex and primarily our criterion for a recommended standard for noise control in industry was targeted to speech frequencies. However, because of unfamiliarity with certain words or maybe inability to interpret what spoken words are, the scientific community has gone to so-called pure tone sounds. These are certain kinds of frequency, where the low frequencies are the hums and the high frequencies are the hisses. We tried to interpret those noise frequencies in terms of what could happen in normal speech understanding. I think that that is the major issue that we would like to concern ourselves with. Based on what we have, there are a number of recommendations which are part of the testimony. I would briefly go through those. NIOSH has recommended that you use pure tone frequencies of 1000, 2000, and 3000 cycles per second, or Hertz, as they are called, plus a "low fence" of 25 decibels. The 25-decibel range of hearing loss is not considered significant. We think that for normal occupations, anyone who has hearing loss in one ear can generally turn his head to hear with the better ear. So we agree with using a formula of weighting the better ear five times more than the poorer one in determining hearing_impairment. We recommended that that formula be retained. We report in our criteria document that as we age we tend to lose hearing, the presbycusis value. We think you might want to consider that. We also think that in certain occupations where it is essential that you hear, such as a telephone operator, that there be some weighting or some consideration of those factors. Hearing loss for someone with a desk job would not be as important as, say, someone who is working in an air traffic control tower where they have to hear messages. So, with those considerations, I turn it back to you, Mr. Chairman, if you or the committee have any questions. [The written statement of Edward J. Baier follows:] STATEMENT OF EDWARD J. BAIER, DEPUTY DIRECTOR, NATIONAL INSTITUTE FOR OCCUPATIONAL SAFETY AND HEALTH, CENTER FOR DISEASE CONTROL, DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE Mr. Chairman and Members of the Subcommittee: I am Edward J. Baier, Deputy Director of the National Institute for Occupational Safety and Health (NIOSH). Before coming to NIOSH in 1972, I was Director of the Bureau of Mines and Occupational Health and Safety for the Pennsylvania Department of Environmental Resources. Accompanying me today are Dr. Alexander Cohen and Mr. B. Thomas Scheib, two of NIOSH's noise researchers. Dr. Cohen is Chief of the Behavioral and Motivational Mr. Factors Branch in the Division of Biomedical and Behavioral Science. noise. We welcome the opportunity to appear before you today to discuss NIOSH research on occupationally-induced hearing loss. In particular you have asked us to discuss the formula by which the Department of Labor determines hearing loss for purposes of compensating Federal employees and other related matters. NIOSH Criteria Document on Occupational Exposure to Noise NIOSH and its predecessor occupational health agencies have conducted research for more than 20 years on the problem of hearing loss in workers caused by workplace noise exposure (1-9). Our primary concern during this time has been devoted to prevention, though, and not with the compensation aspects. In August 1972, NIOSH transmitted a criteria document to the Department of Labor containing recommendations for a new workplace standard for noise control (10). This was one of the first criteria documents developed, because NIOSH recognized that the prevalence of occupational Sizable hearing loss was a high priority concern requiring control. populations of workers are subject to hearing loss risk in such major industries as iron and steel-making, mining, metal fabrication, textiles, lumbering, and printing and publishing in the private sector of U.S. industry. In Federal establishments, noise hazards to hearing are found in printing and engraving shops, ordinance test areas and arsenals, naval shipyards and many other military service occupations, and transportation together with their associated support facilities. NIOSH estimated in the criteria document that more than 2,500,000 industrial workers are exposed to noise levels potentially hazardous to their hearing in major U.S. industries. This does not include the more than 4.5 million transportation workers, 3.5 million construction workers, 626,000 miners and 4.7 million agricultural workers, nor does it include workers employed by government. In general, workplace noise exposures, especially those occurring in mechanized industries, are likely to pose a greater threat to an individual's health and well-being than general environmental noise exposures. Loss of hearing is considered to be the most significant health hazard caused by over-exposure to noise and is the focus of our testimony today. Noise can also interfere with the reception of speech, warning signals and other desired sounds, contribute to physiological and psychological disturbances and hinder work performance. The intent of the NIOSH recommendations for noise control was and is to prevent, or at least minimize, noise-induced disease and injury. The criteria document stressed the need for engineering controls to reduce the intensity of noise in the workplace and administrative controls to limit the amount of exposure each employee receives. The use of ear protectors was sanctioned only as a temporary measure until engineering and administrative controls could be implemented. NIOSH recommended that audiometric tests be given when an employee is initially assigned to a noisy environment and periodically thereafter. Although the NIOSH criteria document does not specifically deal with the issue of compensation for occupational hearing loss, prevention of hearing loss and hearing loss compensation do become interrelated in the course of developing recommendations for noise control. For example, if the primary socioeconomic value of hearing is presumed to be speech communication, then only that hearing loss which handicaps such communication is considered in ́establishing compensation awards. NIOSH set as its goal the preservation of hearing for speech under everyday listening conditions. This goal was not designed to prevent any and hearing loss, as has been the goal of other Federal agencies concerned with general community noise problems, but only that hearing loss which would represent a material impairment--in terms of the worker's safety in the occupational environment, loss of workplace earning potential, difficulty in communication during and following employment. In essence then, the NIOSH recommendations were to prevent losses from becoming disabling and compensable in nature. Moreover, the proposal contained in the NIOSH criteria document that would eventually reduce the current 8 hour noise limit of 90 dBA to 85 dBA for workplace exposure was designed to reduce by half the number of workers who would display such losses at retirement age. Formulas for Determining Hearing Loss Ideally, a person's hearing ability for speech should be measured by presenting a variety of speech material under controlled testing conditions which are typical of everyday listening environments. While there has been progress in devising such tests to determine hearing impairment for compensation purposes, they have not yet been adopted as standardized measures. Questions persist, for example, about the possible unfamiliarity of the speech test items, the vocabulary limitations of the person being tested, the need for extensive equipment, and special training to administer and score the speech tests. Generally hearing is measured through simple tests of pure tone sensitivity as portrayed in audiograms, and relates the threshold hearing levels for certain test tone frequencies to the ability to hear and understand speech. Formulas relating hearing of pure tones to hearing for speech are numerous and date back nearly 50 years (11-15). Perhaps the most popular of those used was one developed by the Subcommittee on Noise of the American Academy of Opthalmology and Otolaryngology and adopted by the American Medical Association in 1961 (15). This formula simply averaged the hearing threshold levels for frequencies 500, 1000 and 2000 Hertz and defined an average of 25 dB (decibels) (re ANSI) (15 dB re ASA) as the "low fence" or point of beginning hearing handicap for speech reception. Impairment was assumed to increase linearly above this average level at the rate of 1 1/2 percent per decibel in excess of the "low fence." Thus, 100. or total hearing impairment was reached for an average value of 93 dâ (ANSI) (82 dB ASA) in this formulation. Calculations for hearing impairment in both ears were also included in this formulation, the better ear being |