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Year : 2009  |  Volume : 11  |  Issue : 42  |  Page : 2--7

The hearing conservation amendment: 25 years later

Alice H Suter 
 Alice Suter and Associates, Ashland, Oregon, USA

Correspondence Address:
Alice H Suter
575 Dogwood Way, Ashland, OR 97520


It has been twenty-five years since the final version of the Hearing Conservation Amendment was issued by the Occupational Safety and Health Administration in the U.S. Department of Labor. Since that time, some things have changed and others have stayed exactly the same. Certainly the noise-exposed workforce is more knowledgeable about the hazards of noise, and the use of hearing protection devices (HPDs) has greatly increased. There have been significant strides in the technology for measuring noise and for protecting hearing through HPDs. But there is considerable room for improvement. Some of the noise regulation's provisions are embarrassingly outdated, some are in dire need of improvement, and others, such as the requirements for engineering noise control, are not being enforced. Sadly, there seems to be little progress in reducing overall noise exposure levels. What needs to be done at this point is a major overhaul of the noise regulation: recommitment to engineering noise control; reduction of the permissible exposure limit (PEL) to 85 dBA; a shift to the 3-dBA exchange rate; and a nationwide assessment of hearing loss in American workers to determine the effectiveness of current hearing conservation measures to identify and address the weaknesses in programs and regulations.

How to cite this article:
Suter AH. The hearing conservation amendment: 25 years later.Noise Health 2009;11:2-7

How to cite this URL:
Suter AH. The hearing conservation amendment: 25 years later. Noise Health [serial online] 2009 [cited 2022 May 16 ];11:2-7
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The purpose of this invited presentation to the 33 rd annual meeting of the National Hearing Conservation Association (NHCA) was to explore the status of the U.S. Occupational Safety and Health Administration's (OSHA) Hearing Conservation Amendment (HCA) 25 years after its promulgation. The presentation was divided into four sections:

Improvements What has slipped through the cracksDegradationsWhat we need

Before exploring these areas, however, it would be useful to review the history of OSHA's noise regulation. This regulation is listed in the U.S. Code of Federal Regulations (CFR) as 1910.95. The original noise regulation was issued in 1969 under the authority of the Walsh-Healey Public Contracts Act, which required all businesses with federal contracts of USD 10,000 or more to protect the safety, health, and rights of their workers. Sections (a) and (b) of the regulation set forward the requirements for the permissible exposure limit (PEL), a time-weighted average level (TWA) of 90 dBA with a 5-dBA exchange rate (for every 5 dB increase in sound intensity, the duration of allowable exposure time is cut in half), to be achieved by engineering or administrative controls. These sections are still in effect today, although not well enforced, and they are not separable from the rest of the regulation. Part 3 of section (b) called for "continuing, effective hearing conservation programs" whenever the PEL was exceeded, but this requirement was seldom honored because employers were not compelled to implement such programs.

After a lengthy period of public comment and bureaucratic delay, OSHA issued sections (c) through (s) of the regulation, along with several appendices, as the HCA in 1981. [1] With a change in federal administration, enforcement of certain sections of the regulation were stayed (held back), some revisions were made, and the revised regulation was issued in 1983. [2] Since that time, there have been no changes to the regulation itself, but some changes have been implemented through policies and interpretations, which can be done without going through the lengthy rule-making process. OSHA can make these changes administratively without the usual public hearings and comment periods, although any such changes can be reversed in the same way.


Although the OSHA noise standard as amended has not been revised in any way during the past 25 years, there have been many changes in the field of hearing conservation, some of them quite beneficial and others not so.

More workers enrolled in hearing conservation programs

First, because the definition of continuing, effective hearing conservation programs (HCPs) is now spelled out in detail, there are undoubtedly many more workers enrolled in these programs. Exactly how many, we don't know, but it's safe to assume that most large employers and many medium-size companies have instituted such programs. We can conclude that many more noise exposed workers have information about their noise exposures and hearing thresholds. The assumption is that this information is beneficial, but documentation of these benefits is yet to be done. We can safely conclude that the use of hearing protection devices (HPDs) has greatly increased, but we also know that many workers, especially in small companies, are still going unprotected. [3],[4] Reliable estimates of the use and effectiveness of these devices would be helpful. Also, we know that many more workers are having their hearing tested, but the fundamental question of whether or not the incidence and prevalence of noise-induced hearing loss is decreasing is yet to be answered.

OSHA advancements

Despite the lack of changes in the regulation itself, there have been some changes within the agency that could be beneficial. Cooperative agreements with NHCA confirm OSHA's recognition that NHCA is the proactive leader in hearing loss prevention in the U.S. There is also a new alliance between OSHA, the National Institute for Occupational Safety and Health (NIOSH), and NHCA for the development of training courses on noise and hearing loss prevention, promoting and sharing information on best practices, and designing a model HCP for the construction and maritime industries. OSHA has also developed a website with NHCA that provides information on noise effects, regulations, evaluation of exposures, and what constitutes an effective program.

After many years of deliberation, OSHA has issued a final standard (in CFR 1004.10) on recording hearing loss on the OSHA 300 Log as part of a broad set of requirements for recording occupational diseases and injuries. [5] This is a step in the right direction, although the 1981 version of the amendment contained a more rigorous rule. The 1983 version was silent on the subject. Now the basic requirement is that if an employee's audiogram reveals a standard threshold shift (STS) and the total average hearing level in that ear is 25 dB or more above audiometric zero, the STS must be recorded in the OSHA 300 Log. The current audiogram may be adjusted for aging. The existence of any recording requirement could be considered an advancement but progress is diminished by the permissive nature of the requirement. State-run OSHA programs with more stringent requirements that existed before the current regulation have now been preempted from enforcing them.

Over recent years, OSHA has issued several safety and health bulletins on noise and hearing conservation. Examples include two bulletins issued in 2005 ( ). The first of these bulletins, " Innovative Workplace Safety Accommodations for Hearing-Impaired Workers ," describes the challenges faced by hearing-impaired workers, informs employers of available accommodations, and encourages them to develop and establish procedures that further safety and health in the workplace. The second bulletin, " Hearing Conservation for the Hearing-Impaired Worker ," acknowledges communication and safety problems that can occur with HPD use and describes a variety of special protectors, including active HPDs and earmuffs with communication features.

Standards and regulations

There have also been improvements for noise exposed workers in the form of new and revised standards and regulations. Construction workers, who are still covered by the original OSHA regulations without benefit of the HCA, have at least benefited by increased activity in the realm of consensus standards. A team of health professionals, union representatives, and members of the manufacturing and contracting communities have issued an ANSI/ASSE consensus standard, A10.46 - 2007: " Hearing Loss Prevention for Construction and Demolition Workers ." [6] ANSI/ASSE A10.47 contains many improvements over the current OSHA regulation. Here are some examples:

Engineering and administrative controls should be used when feasible at or above sound levels of 85 dBA, and these controls are mandatory over a TWA of 105 dBA. The standard also calls for warning signs and HCP evaluation - two aspects that are lacking in the existing OSHA noise standard. Method B of ANSI S12.6 - 1997 should be used for testing the attenuation of HPDs, and a derating scheme is provided for HPDs that are already labeled with the current noise reduction rating (NRR). Audiometric test rooms should meet the standards for background noise levels recommended by NHCA in 1996.STS is to be recorded in the worker's medical record unless a professional reviewer determines that the hearing loss is unrelated to noise.

More improvements have come in the form of regulations. The U.S. Mine Safety and Health Administration (MSHA) issued a new noise regulation in 1999. [7] The new MSHA regulation contains some improvements over OSHA's, mainly in the hierarchy of controls, where engineering and administrative controls are still the first order of protection for exposed workers. (Although OSHA's regulation has not changed in this regard, enforcement policies are no longer consistent with these requirements.) Other improvements in the MSHA regulation are in the areas of posting and notification. In one sense, the MSHA regulation is more lenient than OSHA; the mine operator must offer and provide the opportunity for baseline and annual audiometric testing, whereas OSHA uses the term shall establish baseline and annual audiograms (Here the OSHA regulation is somewhat ambiguous because section (g)(1) requires employers to make "audiometric testing available…" whereas section (g)(5) uses the words "shall establish a valid baseline….").

The U.S. Federal Railroad Administration (FRA) issued a new regulation in 2007, [8] which is similar to OSHA's in many respects, but with some additional weaknesses. For example, it allows exposures to continuous noise of up to 120 dBA; periodic audiograms must be 'offered' annually (with no definition of 'offered') but required only once every 3 years; and the regulation allows longer time periods for retests and notification. One beneficial change is a provision for the optional use of insert earphones for audiometric testing and an appendix giving allowable sound levels in audiometer rooms for these earphones that is consistent with ANSI S3.1, 1999. The allowable levels for supra-aural earphones, however, are derived from the same outdated standard used in OSHA's 1983 regulation. While this regulation is better than nothing, it contains few of the improvements that could have resulted from the experience gained over the past 25 years.

Criteria and recommendations

Another source of improvement since the date of OSHA's hearing conservation regulation is the wealth of criteria and recommendations by government and consensus organizations advocating more protective levels and methods of assessing noise effects. Notable examples are the revised NIOSH criteria document for noise [9] and recommendations by organizations such as the American Academy of Audiology, [10] the American Conference of Governmental Industrial Hygienists (ACGIH), [11] the American Industrial Hygiene Association (AIHA), [12] the International Safety Equipment Association (ISEA), [13] and the NHCA. [14] In 2002, the Coalition to Protect Workers' Hearing submitted detailed recommendations to OSHA in response to an advance notice of proposed rulemaking concerning HCPs for construction workers. [15] Members of the Coalition included the American Academy of Audiology, the American Association of Occupational Health Nurses, The American Speech-Language-Hearing Association, the Council for Accreditation in Occupational Hearing Conservation, the NHCA, and Self Help for Hard of Hearing People, Inc. All these organizations have endorsed an 85 dBA PEL and the 3 dBA exchange rate.

Research on combined exposures to noise and other agents

There has been significant progress in understanding the effects of noise when combined with other workplace agents, particularly toxic chemicals. Two recent conferences have brought together experts from around the world to share their research on these topics. The " Best Practices Workshop: Combined Effects of Chemicals and Noise on Hearing" was presented by NIOSH in Cincinnati on April 11-12, 2002. The international symposium " Health Effects of Exposure to Noise and Chemicals" (sponsored by the NOFER Institute of Occupational Medicine), took place in Lodz, Poland, November 15, 2006. Important reviews on these subjects have recently been published by Fecter, [16] Fuente and McPherson, [17] Morata [18] and Sliwinska-Kowalska et al . [19] Despite a considerable amount of research in this area, criteria supporting dose-response relationships are yet to be developed. However, attempts to develop benchmarks to identify chemical exposures that will begin to potentiate noise-induced hearing loss are in progress. [16] While several organizations are urging caution whenever workers are exposed to both noise and ototoxic chemicals, [11],[20],[21] in the U.S. little attention is paid to such cautions.

Engineering noise control

Since 1983, there has been some progress in the control of noise exposure by engineering means, despite the lack of incentive provided by OSHA. There is a tendency toward quieter consumer products, and U.S. manufacturers have discovered that they need to reduce the noise levels of machines they hope to market in Europe. Some of these quieter machines find their way to the American workplace, but the effect is still small. Most of the research in noise reduction has been conducted by the Bureau of Mines and more recently by NIOSH.


In the past 25 years, there have been significant advances in noise measurement equipment. We now have dosimeters and integrating sound level meters with large dynamic and pulse ranges and with the ability to store, analyze, and interpret large amounts of data. Audiometric test equipment has also improved during the last two decades. Microprocessors with extensive capabilities are in common use, with software that can perform a vast number of operations, such as presenting instructions in multiple foreign languages. Sensors that continuously monitor noise levels in test environments are also available.

Education and training programs

Hearing loss prevention (HLP) education, training, and motivational programs have become more sophisticated by utilizing personal computers and interactive modules. Significant information has been obtained through recent research addressing barriers to changes in behavior, [22],[23] but the extent to which these techniques are actually used is not known. Several HLP programs for children have been developed through advocacy by NHCA and other professional organizations. Although it may appear that these programs do not apply to hearing preservation in the occupational setting, one must remember that today's children will be tomorrow's workers, supervisors, managers, and teachers.

 What has Slipped Through the Cracks?

Underserved workers

While workers in manufacturing, maritime, mining, and the military are covered by noise and hearing conservation regulations, there are probably a million noise exposed workers in the U.S. who are inadequately protected or not covered at all:

Agricultural workers : There is no noise regulation for these workers, although there is professional interest in implementing HLP programs for them, especially in farming communities.Construction workers : These workers are still covered by a regulation, 29 CFR 1926.52, which is similar to the old 'bare bones' OSHA noise standard without hearing conservation provisions. However, some unions, contractors, and company representatives have stepped into the breach with the development and publication of ANSI/ASSE A10.46 - 2007, as explained in a previous section of this article.Oil and gas well drilling and servicing workers: There is no noise regulation for these workers.

ANSI standards referenced in OSHA's hearing conservation amendment

Many of the standards referenced in the HCA are embarrassingly out of date. The most extreme example is the reference to ANSI S3.1-1960, Criteria for Background Noise in Audiometer Rooms. The standard itself is not listed in the body of the regulation, but Appendix D specifies levels at the pertinent frequencies (500-8000 Hz), which are the same as those in the 1960 standard. These levels were originally meant to allow testing to 0 dB according to the old standard for audiometric zero, Z24.5-1951, which changed in 1969. But OSHA's regulation didn't take that change into account, and the background noise levels currently specified are more than half a century out of date! (See explanation in the preamble to the 1981 OSHA HCA [1] )

The increasing use of insert earphones could mitigate this problem considerably, and although their clinical use is widespread, they are still rarely used in occupational HCPs.

There are several other ANSI standards that do not appear in OSHA's noise regulation, but should be considered for addition. They include:

ANSI S1.40 Specification for Acoustical CalibratorsANSI S1.43 Specification for Integrating Averaging Sound Level MetersANSI 3.21 Methods for Manual Pure-Tone Threshold AudiometryANSI S12.6 Methods for Measuring the Real-Ear Attenuation of Hearing ProtectorsANSI S12.13 (Technical Report) Evaluating the Effectiveness of Hearing Conservation Programs through Audiometric Data Base AnalysisANSI S12.19 Measurement of Occupational Noise ExposureANSI S12.25 Specification for Personal Noise Dosimeters

Dosimeter lower threshold

Contradictions are evident in the OSHA regulation with regard to setting the lower threshold of dosimeters. Because sections (a) and (b) of the existing standard were not changed when it was amended for HCPs, employers were still allowed to calculate the PEL for compliance with engineering and administrative controls differently than for compliance with the amendment's provisions. Thus, they could count levels below 90 dBA as zero, but needed to set the lower threshold level at 80 dBA when assessing compliance with the newer provisions. This led to two kinds of dosimeter measurements with the option of resetting the instrument for each kind. The absurdity of considering sound levels at and below 89.9 dBA as harmless should be obvious. Hopefully, companies will use the single 80 dBA lower threshold for all measurements.

HCP evaluation

There is nothing in the OSHA regulation requiring or even recommending the evaluation of HCPs. Such evaluations have been strongly recommended, however, by NIOSH, NHCA, the Council for Accreditation in Occupational Hearing Conservation (CAOHC), and other organizations. ANSI S12.13 is just one form of program evaluation, but there are many more, including checklists, observations of the use of HPDs by workers, analyzing the occurrence of STS, and the measurement of progress in noise reduction. While some companies use these types of evaluation tools, most do not.



One of the most serious impediments to progress in the prevention of noise-induced hearing loss is the relaxation of enforcement by OSHA in the years since the amendment was promulgated. This has occurred during Democratic as well as Republican administrations, and applies to the HCA sections as well as to the requirements for engineering and administrative controls. Without enforcement, compliance necessarily diminishes.

Death knell for noise control

In November of 1983, just after OSHA had promulgated the revised version of the HCA, the agency issued a directive to its compliance officers in the field stating that they should not issue a citation for engineering controls until workers' TWA's exceeded 100 dBA. [24] This document, Instruction CPL 2-2.35, has since been incorporated into OSHA's enforcement manual and is still in effect today. OSHA has been severely criticized for this policy by individual professionals and several different organizations, but OSHA has not responded to these criticisms. What the agency has done may be considered ' de facto ' raising of the PEL without following required regulatory procedures. In the words of the policy memo:

Control is not reasonably necessary when an employer has an ongoing hearing conservation program and the results of audiometric testing indicate that any existing controls and hearing protectors are adequately protecting employees.

The phrase "adequately protecting employees" has never been satisfactorily defined. It is clear from the preamble to the 1981 version of the HCA that it was never meant to replace requirements for engineering and administrative controls. This author knows of no other OSHA regulation that has been thus emasculated by a compliance policy. The incentive for employers to design quieter workplaces and quieter equipment for employees is not provided by OSHA.

European versus U.S. requirements

While U.S. regulations for occupational noise exposure have languished, the Europeans have been moving ahead rapidly. European noise legislation requires quieter equipment and the labeling of noisy products. [20] There are also programs in Europe to provide incentives to manufacturers of noise-producing equipment, such as air compressors, to exceed the noise reduction requirements of European standards. It has been suggested that the incentive for U.S. manufacturers to sell quieter equipment abroad will provide benefits that will filter down to American workers, but few signs of this have appeared to date.

Over-reliance on HPDs

In the absence of incentives for noise control, there has been a degree of over-reliance on HPDs. Although there is no denying HPDs provide a major contribution to preserving hearing, such devices still should be third in the hierarchy of controls, after engineering and administrative controls. Field tests have demonstrated that some HPDs may not provide sufficient attenuation. [25] Moreover, there is always a possibility of over-attenuation, especially with hearing-impaired workers. Accidents, interference with speech communication and warning signal recognition are all possible unless appropriate HPDs are provided. Comfort of HPDs continues to be a very important and under-appreciated issue. A protector that is uncomfortable is unlikely to be worn.

 What We Need

Here is a short list of what the U.S. needs to improve our HLP efforts. These needs are not necessarily listed in order of priority, but should be addressed concurrently.

Withdraw CPL 2-2.35 and the related language in OSHA's field instructions manual and begin enforcing the provisions for engineering and administrative controls.

Reduce the PEL to 85 dBA and adopt a 3 dB exchange rate (to match the standards in most of the rest of the world).

Use a new, more economical, and sensible approach to noise regulation:

Lower levels for new plants and processes. Deadlines by which employers can implement noise reduction. Labeling requirements for noisy equipment. Regulations for product noise emission. Reestablish EPA's Office of Noise Abatement and Control to assist with labeling and regulating product noise. Promulgate regulations for construction, agriculture, and oil well drilling and servicing workers. Revise the 1983 version of the HCA to bring its policies into the 21 st Century.

Perform a major assessment of hearing loss in American workers to determine the effectiveness of current HCPs, and to identify and address the weaknesses of these programs.


1OSHA. Occupational Noise Exposure: Hearing Conservation Amendment. U.S. Dept. Labor, Occupational Safety and Health Administration, 46 Fed Reg 1981. p. 4078-179.
2OSHA. Occupational Noise Exposure: Hearing Conservation Amendment; final rule. U.S. Dept. Labor, Occupational Safety and Health Administration, 48 Fed. Reg.; 1983. p. 9738-84.
3Reilly MJ, Rosenman KD, Kalinowski DJ. Occupational noise-induced hearing loss surveillance in Michigan. J Occup and Environ Med 1989;40:667-74.
4Daniell WE, Fulton-Kehoe D, Cohen M, Swan SS, Franklin GM. Increased reporting of occupational hearing loss: Workers' compensation in Washington State, 1984-1998. Am J Indust Med 2002;42:502-10.
5OSHA. Occupational Injury and Illness Recordkeeping and Reporting Requirements; final rule. U.S. Dept. Labor, Occupational Safety and Health Administration, 67 Fed. Reg. 2002. p. 44124-7.
6American National Standard ANSI/ASSE A10.46-2007. Hearing Loss Prevention for Construction and Demolition Workers. American Society of Safety Engineers, 1800 E. Oakton St., Des Plaines, IL 60018; 2007.
7MSHA. Health standards for occupational noise exposure: Final rule, Mine Safety and Health Administration. 30 CFR Part 62, 64 Fed. Reg. 1999. p. 49548-634, 49636-7.
8FRA. Part 227- Occupational Noise Exposure. U.S. Dept. Transportation, Federal Railroad Administration. 71 Fed. Reg. 2006. p. 63123-38.
9NIOSH. Criteria for a Recommended Standard: Occupational Noise Exposure; Revised Criteria. National Institute for Occupational Safety and Health, U.S. Dept. HHS, report DHHS (NIOSH) 98-126, Cincinnati, OH; 1998.
10American Academy of Audiology Position Statement: Preventing Noise-Induced Occupational Hearing Loss. NHCA Spectrum; Vol. 21(1), 2004.
11ACGIH. Threshold Limit Values for Chemical Substances and Physical Agents, and Biological Exposure Indices. Supplement: Noise. Cincinnati, OH: American Conference of Governmental Industrial Hygienists; 2000. p. 1-11.
12Letter from AIHA President Frank M. Renshaw to assistant secretary of labor. Edwin G. Foulke; 3-26-07.
13Letter from ISEA President Daniel Shipp to Assistant Secretary of Labor Edwin G. Foulke, based on position paper for ISEA dated 12-8-06 by Alice H. Suter; 1-26-07.
14Written comments submitted by the National Hearing Conservation Association to the Federal Railroad Administration, U.S. Department of Transportation; 9-20-04.
15Written testimony submitted by the Coalition to Protect Workers' Hearing to the Occupational Safety and Health Administration in response to the Advanced Notice of Proposed Rulemaking: Hearing Conservation Program for Construction Workers; 11-4-02.
16Fechter LD. Promotion of noise-induced hearing loss by chemical contaminants. J Toxicol Environ Health A 2004;67:727-40.
17Fuente A, McPherson B. Organic solvents and hearing loss: The challenge for audiology. Int J Audiol 2006;45:367-81.
18Morata TC. Promoting hearing health and the combined risk of noise-induced hearing loss and ototoxicity. Audiol Med 2007;5:33-40.
19Sliwinska-Kowalska M, Prasher D, Rodrigues CA, Zamyslowska-Szmytke E, Campo P, Henderson D, et al . Ototoxicity of organic solvents-from scientific evidence to health policy. Int J Occup Med Environ Health 2007;20:215-22.
20EC. Directive 2003/10/EC of the European Parliament and of the Council on the minimum health and safety requirements regarding the exposure of workers arising from physical agents (noise). (Seventeenth individual Directive within the meaning of Article 16(1) of Directive 89/391/EEC); 2003.
21U.S. Army pamphlet 40-501, Hearing Conservation Program. Headquarters, Dept. Army, Wash DC, 10 Dec. 1998.
22Lusk SL, Ronis DL, Kerr MJ. Predictors of hearing protection use among workers: Implications for training programs. Hum Factors 1995;37:635-40.
23Stephenson MR. Empowering the worker to prevent hearing loss: The role of education and training. Proceedings of the National Hearing Conservation Assoc; Feb 23, 1996.
24OSHA. Instruction CPL 2-2.35, Nov. 9, 1983 in Guidelines for Noise Enforcement. Occupational Safety and Health Administration, U.S. Dept. Labor, Washington DC: 1983.
25Berger EH. Hearing protection devices. In: Berger EH, Royster LH, Royster JD, Driscoll DP, Layne M, editors. The noise and hearing conservation manual, rev. 5 th ed. Fairfax, VA: American Industrial Hygiene Assoc. 2003. p. 379-454.