ASA Lay Language Papers
161st Acoustical Society of America Meeting

How can we prevent hearing loss when there is loud noise at work?

Thais C. Morata-
National Institute for Occupational Safety and Health
4676 Columbia Parkway
Cincinnati, OH 45226, USA

Popular version of paper 5aNS4
Presented Friday morning, May 27, 2011
161st ASA Meeting, Seattle, WA

Greater demands for accountability over federal funds have motivated an interest in studies on the effectiveness of public health interventions.  In 2009, the American Recovery and Reinvestment Act provided federal funding to investigate how different interventions stack up against each other. In the same Act, Congress asked the Institute of Medicine (IOM), a National Academy of Sciences organization, to identify priorities for these studies of comparative effectiveness. To establish such priorities, the law required the IOM to seek advice from stakeholders, including  researchers, physicians, professional organizations, and the general public. The IOM’s recommendations are contained in the report Initial National Priorities for Comparative Effectiveness Research, available online at  The need for research on hearing loss interventions was placed in the top quartile, the highest priority group.   
The IOM recommendation underscores the human and societal costs of the condition and the importance of prevention. The risk of hearing impairment increases with age and is exacerbated by exposure to noise, particularly at work.  Estimates indicate that one in six people will have seriously impaired hearing in older age because of occupational noise exposure. This risk can be essentially eliminated by reducing noise levels to 80 dB(A) or less.  Many countries have mandated hearing loss prevention programs when noise exposures cannot be reduced to this level. However, the continuing high rate of noise-induced hearing loss casts doubt on the effectiveness of these programs.

Results from the existing intervention effectiveness studies on hearing loss prevention in the workplace do not provide much evidence for current hearing loss prevention practices (Dobie, 1995; Borchgrevink, 2003; Daniell et al., 2006; Davies et al., 2008; Heyer et al., 2010). A 2009 Cochrane Review investigated various initiatives and mechanisms (e.g., legislation, proper hearing protector usage, etc.) to determine which work best to reduce noise levels in workplaces and/or reduce noise exposure or hearing loss among workers (Verbeek et al., 2009). [Cochrane Reviews are published by the Cochrane Collaboration, an independent international not-for-profit organization dedicated to examining the evidence for or against the effectiveness of health care interventions].  The 2009 Cochrane Review identified 21 intervention studies meeting their criteria for scientific rigor, most of which concerned hearing loss prevention programs.  While the review found that legislation was effective in reducing noise levels (based on one study in the U.S. mining industry), it found contradictory evidence on the effectiveness of hearing conservation programs and hearing protection devices. Comparisons of unexposed workers to exposed workers who used hearing protection ranged from no difference to three- or four-fold increases in noise-induced hearing loss among those noise-exposed who wore hearing protetors. Four studies attributed these disparate results to variability in the implementation of various program components within and across industries. There is consensus that programs are often incomplete and over-rely on the distribution of hearing protection devices to reduce individual worker exposure. Better and large scale implementation of technical interventions and evaluation of their long-term effects are necessary to identify the most effective strategies for reducing occupational hearing loss.

This did not escape the attention of the U.S. Occupational Safety Health Administration (OSHA). "There is sufficient evidence that hearing protection alone cannot prevent workers from suffering preventable hearing loss," said David Michaels Assistant US Secretary of Labor for Occupational Safety and Health. On October  19, 2010,  OSHA published a notice in the Federal Register proposing a small but important change to the noise standard (Section (b)(1)). This standard requires employers to use feasible engineering or administrative controls for workers exposed to average noise levels above 90 dB(A).  Up to now, feasible has been interpreted to mean costing less than a hearing conservation program. OSHA proposed to interpret feasible in its plain meaning – i.e.,  capable of being done (Docket No. OSHA-2010-0032). The National Institute for Occupational Safety and Health (NIOSH) supported the change proposed by OSHA, citing the evidence from the reports mentioned above (NIOSH, 2010).  NIOSH indicated that technical measures to control noise, where feasible, offer advantages for both the employer and the worker, including reduced hearing loss, lower compensation costs, improved communication, decreased absenteeism, and fewer injuries in the workplace (NIOSH, 1998; Driscoll and Royster, 2003). NIOSH also provided real-world examples showing that technological advances now enable quieting machinery and workplaces without adding substantially to the cost of operating a business.  For the past three years, NIOSH and the National Hearing Conservation Association have awarded the Safe-in-Sound Excellence in Hearing Loss Prevention Award™ to companies and public agencies which have proactively implemented technical solutions resulting in substantial cost savings compared to enrolling all employees in company-wide hearing conservation programs (  These examples demonstrate the diversity of solutions that can be employed to reduce or eliminate noise through the use of technical noise controls. 

On January 20, 2011, OSHA withdrew its proposed reinterpretation of feasible noise controlsto allow more public outreach and further study of the resources required for implementation.  OSHA indicated that, while the proposed modification is suspended, it will study other approaches to abating workplace noise.
Meanwhile, hearing loss investigators at NIOSH, in addition to conducting and publishing research, are making use of new communication tools and social media, such as the NIOSH Science Blogs, Wikipedia, Facebook, and NIOSH NoiseTwitter, to reach out to the general public and occupational health community,  improve the exchange of information, and expedite progress in hearing loss prevention. Links to such efforts are provided below.  NIOSH received the 2011 National Hearing Conservation Association Media award for this undertaking.

Useful Links:
Borchgrevink HM. Does health promotion work in relation to noise? Noise Health 5,25-30 (2003)
Daniell WE, Swan SS, McDaniel MM, et al. Noise exposure and hearing loss prevention programmes after 20 years of regulations in the United States. Occup Environ Med 63,343-51 (2006).
Davies H, Marion S, Teschke K. The impact of hearing conservation programs on incidence of noise-induced hearing loss in Canadian workers. Am J Ind Med 51,923-31 (2008).
Dobie RA. Prevention of noise-induced hearing loss. Arch Otolaryngol Head Neck Surg 121, 385-91 (1995).
Driscoll DP,  Royster LH. Noise Control  Engineering.  Ed. EH Berger, LH Royster, JD Royster, et al.  The Noise Manual.  2003. AIHA Press, Fairfax VA.
Heyer N, Morata TC, Pinkerton LE,  et al. Use of historical data and a novel metric in the evaluation of the effectiveness of hearing conservation program components. Occup Environ Med. 2010 [Epub].
Verbeek JH, Kateman E, Morata TC, et al. Interventions to prevent occupational noise-induced hearing loss. Cochrane Database Syst Rev 2009 Jul 8, Issue 3. CD006396.
National Institute for Occupational Safety and Health , NIOSH.  Criteria for a Recommended Standard, Occupational Noise Exposure – Revised Criteria. 1998,  NIOSH, Cincinnati.
National Institute for Occupational Safety and Health (NIOSH), 2010. Comments on the Occupational Safety and Health Administration Proposed Interpretation Provisions for Feasible Administrative or Engineering Controls of Occupational Noise. Docket No. OSHA-2010-0032. December 20, 2010, Cincinnati.
Occupational Safety and Health Administration (OSHA) 2010. OSHA’s provisions for feasible administrative or engineering controls of noise, Federal Register, October 19, 2010 [75 FR 64216].

Disclaimer. The findings and conclusions in this report are those of the author and do not necessarily represent the views of the US National Institute for Occupational Safety and Health