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sound waves, ear

Activities: NIOSH Research Projects

NIOSH is executing a planned program of research in occupational hearing loss. The mission of the HLR program is to provide national and world leadership to reduce the prevalence of occupational hearing loss through a focused program of research and prevention. It is divided into four areas of research:

  • Hearing loss prevention program areas
  • Hearing protection devices
  • Engineering control of noise sources
  • Surveillance and risk factors

The research conducted in each of these areas is based on the advice of internal and external researchers, occupational safety and health practitioners, manufacturers of protective devices, employers, and worker groups. We are managing the Hearing Loss Research (HLR) Program so that our efforts can be adjusted to reflect progress and emerging issues. We also manage the program to ensure scientific relevance, quality, and performance, using peer review and regular management review of research activities and outputs.

Research Area 1: Contribute to the development, implementation, and evaluation of effective hearing loss prevention programs

The HLR program conducts three streams of research designed to improve HLPPs. The first HLR program focus is on developing criteria for recommended standards (e.g., ANSI and ISO standards, standards of practice for hearing loss prevention professionals, and recommendations to regulatory agencies). Second, the HLR program investigates hearing conservation program approaches, methods, and materials to develop and field-test best practices. The third HLR program focus applies principles from social psychology, persuasion science, social marketing, and health communication to create training and information programs that meet the needs of intended audiences and improve the motivation of employers and employees to protect hearing.

Research Area 2: Reduce hearing loss through interventions targeting personal protective equipment

The NIOSH hierarchy of controls orders engineering and administrative controls ahead of personal protective equipment (PPE). However, sometimes hearing protection devices (HPDs) are the only practical option for reducing workers’ noise exposures. For this reason, one of our research goals is to reduce hearing loss through interventions targeting personal protective equipment, which for noise are HPDs. Our HPD research is developing better methods for rating HPD effectiveness, including developing procedures to estimate the adequacy of a hearing protector as it would be worn on the job. In particular, we are working on a comprehensive solution that will integrate fit-testing and audiometric screening. Other areas of HPD research include understanding the extent to which HPDs protect against impulsive noise and how to use HPDs to protect hearing-impaired workers.

Research Area 3: Develop engineering controls to reduce noise exposures

Application of engineering noise controls is the most desirable approach to reducing exposure to noise in the workplace and the noise-induced hearing loss that often results. Engineering noise controls reduce or eliminate the noise at its source and ensure that workers are not overexposed. Other approaches to reducing exposure, such as administrative controls and personal protection, are less effective because they rely on human actions.

The HLR program began to focus some of its efforts on engineering controls of noise in the mining and construction industries in 2001. The program’s approach is to first gather and analyze information on noise emission levels to identify the highest noise producing equipment used in the mining and construction industries. Once the equipment is identified, existing engineering noise controls are investigated for their effectiveness and feasibility. Where controls do not exist, engineering controls must be designed, developed, implemented, and tested for the noise-producing equipment. The final stages of this approach are then to motivate the use of engineering noise controls through collaboration with other government agencies, unions, equipment manufacturers, and standards setting bodies and to develop necessary dissemination activities.

Research Area 4: Improve understanding of occupational hearing loss through surveillance and investigation of risk factors

Understanding the fundamental mechanisms of hearing loss allows the HLR program to improve prevention methods and technology. We do not yet understand many aspects of work-related hearing loss. Five lines of research are focus on this goal. These include (1) developing methods that could be applied to establish national occupational hearing loss surveillance methods; (2) improving our understanding of the risk criteria associated with impulsive noise, and how best to measure impulsive events; (3) improving our understanding of risk factors associated with ethnicity and aging; (4) understanding the role of genetics regarding individual susceptibility; and (5) understanding hearing loss due to ototoxicants (such as solvents, heavy metals, and asphyxiates) alone or in combination with noise.

Details about these research goals and subgoals, as well as their associated research efforts can be found here .