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Administration: Office of Environmental Health & Safety

Noise and Hearing Conservation

Noise, defined as unwanted sound, is one of the most common hazards in workplaces in the United States. The National Institute for Occupational Safety and Health (NIOSH) estimates that 30 million workers are exposed to hazardous noise. Exposure to hazardous levels of noise may cause hearing loss. Non-hearing related effects of exposure to noise include physical and psychological stress, fatigue, increased blood pressure, reduced productivity, communication interference and increased incidence of accidents and injuries by making it difficult to hear warning signals.

Sound (and noise) is produced when there is a rapid variation of atmospheric pressure caused by some disturbance of the air. The ear perceives the variations in pressure as sound. The vibrations are converted into mechanical energy by the middle ear, subsequently moving microscopic hairs in the inner ear, which in turn convert the sound waves into nerve impulses. If the vibrations are too intense, over time these microscopic hairs can be damaged, resulting in noise-induced hearing loss (NIHL), a type of sensorineural hearing loss.

The Occupational Safety and Health Administration (OSHA) has set a Permissible Exposure Limit (PEL)  on noise of 90 dBA, based on a worker's time weighted average (TWA) over an 8 hour day. The OSHA Action Level is half the PEL, or 85 dBA as a TWA. At exposures at the Action Level, controls must be put in place to reduce exposures.

The best strategy for noise control is to eliminate exposure to hazards that can lead to hearing loss. The hierarchy of controls for noise is as follows:

  • Engineering controls: prevent or contain noise at its source (e.g. equipment modification or relocation);
  • Administrative controls: Hearing Conservation Program, employee training, work schedule adjustment;
  • Personal protective equipment (PPE): control noise exposure with barriers between the worker and the hazard (hearing protection devices, e.g. earmuffs and earplugs).

Control of noise often involves a combination of each type of control. Hearing protection devices (HPDs) are considered the last line of defense for controlling noise exposures. To obtain the most protection from HPDs, workers must be properly trained in their use and their limitations. The best hearing protector, when fitted correctly, is one that is accepted by the worker and worn properly.
The campus has been surveyed for specific noisy environments, equipment and tasks. Please contact Environmental Health & Safety for more information on the Hearing Conservation Program.

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