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Health and Safety Guide



    Noise is defined as unwanted sound. Individuals who work in areas where high noise levels (more than 85 decibels averaged over eight hours) exist are required to be enrolled in the Princeton University Hearing Conservation Program. The purpose of the program is to prevent noise-induced hearing loss caused by exposure to loud and prolonged noise.

    The federal Occupational Safety and Health Administration (OSHA) permissible exposure limit for noise is a time-weighted average (sound levels averaged over an 8 hour day) of 90 dB (decibels). A healthy person exposed below this level, day after day, is unlikely to experience noise-induced hearing loss. No individual may be exposed to noise levels above 115 dB at any time.

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Scope and Application

    Several areas of the University have been monitored and designated as high noise areas. A high noise area is defined as an area in which sound levels equal or exceed a time weighted average (TWA) of 85 dB or in which sound levels exceed 115 dBA at any time. The Hearing Conservation Program and the OSHA Occupational Noise Standard apply to individuals working in high noise areas.

    Noise levels below 85 dB (averaged over 8 hours) are considered nuisance noise. While nuisance noise does not generally cause injury directly, in some instances it may mask sounds indicative of other developing hazards and may be a source of annoyance. While the Office of Environmental Health and Safety (EHS) may take measurements or provide other consultative services in instances of nuisance noise, it is not the purpose of the Hearing Conservation Program to deal with such situations.

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Program Description


    Surveys of high noise areas are conducted on a semi-annual or annual basis by EHS. For those areas in which a variation in sound level may be expected to occur on a seasonal basis (such as the Chilled Water Plant), some minor adjustments in scheduling may be necessary to ensure that a peak load condition exists during the survey. In the event of process changes, facility renovations, equipment additions, or upon request, additional noise surveys may be conducted at the discretion of EHS.

    Noise monitoring results are forwarded to the person monitored and his or her supervisor in a confidential letter. Individuals may observe any noise measurements taken by EHS.

    It is the responsibility of the department supervisor to post the following information on sources of high noise:


    Where high noise sources are stationary, department supervisors post signs to this effect. Small stickers (available through EHS) are affixed to mobile sources of high noise.

    Audiometric Testing

    All individuals working in high noise areas must be enrolled in the Audiometric Testing Program. Within six months of the first high noise exposure, these individuals must receive a hearing test to establish a baseline audiogram. The audiogram is performed by Employee Health personnel in University Health Services at McCosh, free of charge. High noise exposure must be avoided for 14 hours prior to an exam.

    Audiograms are then given at least annually and compared to the baseline audiogram to determine if a threshold shift exists. A threshold shift has occurred if the hearing threshold has changed by an average of 10 dB or more in either ear, measured at 2000, 3000, or 4000 Hz. If any changes in hearing are noted, the individual is notified by Employee Health.

    Persons enrolled in the Audiometric Testing Program must have a termination audiogram upon leaving Princeton University.

    Hearing Protection

    Noise reduction may be accomplished through use of engineering controls such as enclosing or altering noisy equipment. Sound absorbing materials, which usually absorb 70% or more of the sound that strikes them, may be placed above or around noisy equipment or work areas.

    When engineering controls are not enough to reduce exposure to acceptable levels, hearing protectors may be worn. Hearing protectors act as barriers to reduce sound entering the ear. Use of hearing protection is mandatory for anyone exposed at or above a TWA of 90 dB, and are recommended for those exposed at or above a TWA of 85 dB. Those who have not yet received a baseline audiogram and those experiencing a threshold shift are also required to wear hearing protection at levels above 85 dBA.

    There are many types of hearing protectors available, including disposable or reusable plugs, headband plugs, and muffs. Reusable hearing protectors should be cleaned often and replaced when the plugs or muff cushions become hardened or discolored. It is important that the plugs are seated properly in the ear, that the muffs form an adequate seal around the ear and that the headband is not bent. All of these precautions will improve the noise attenuation (reduction) achieved by the hearing protection.

    A Noise Reduction Rating (NRR), usually stamped on the hearing protector or its packaging, indicates how much noise the particular hearing protector attenuates, usually between 20-29 dB. EHS will evaluate what type of hearing protector offers adequate attenuation for the work area.


    All personnel exposed at or above a time-weighted average of 85 dB must receive Hearing Conservation Training annually. This training is provided by EHS and includes:

    • effects of noise on hearing
    • purpose of hearing protection
    • types of hearing protection
    • selection, use, fitting and care of hearing protectors
    • purpose and procedures for audiometric testing

    It is the responsibility of the supervisor to assure that workers attend this training annually and to keep records of attendance.

    Access to Information and Recordkeeping

    Persons enrolled in the Hearing Conservation Program are given a copy of the OSHA Occupational Noise standard. An additional copy is posted in high noise workplaces.

    Exposure monitoring results are filed at EHS. Audiometric testing reports are filed at McCosh Health Center. Either of these records may be accessed upon request and may be transferred to a new employer when an individual leaves Princeton University.

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Roles and Responsibilities


    • Post copy of OSHA Occupational Noise Exposure regulation.
    • Notify EHS when new noise sources are introduced.
    • Minimize noise using engineering controls.
    • Offer a variety of hearing protectors


    • Post signs or stickers on high noise areas.
    • Ensure workers wear hearing protection.
    • Ensure workers receive training and audiograms.

Employee Health

  • Conduct audiometric testing.
  • Notify individuals and EHS when an standard threshold shift is identified.
  • Refer individuals to specialists when necessary.


    • Conduct monitoring and offer training.
    • Advise on noise reduction through administrative or engineering controls.
    • Recommend appropriate hearing protectors.
    • Audit departmental program periodically.


    • Attend training and receive audiometric testing.
    • Wear appropriate hearing protection when needed at work and minimize noise exposure outside of work.

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For More Information

Contact EHS Health and Safety Specialist at 258-5294.

A Noise and Hearing Conservation Self-Audit Checklist is available through EHS or may be downloaded either as a PDF or a customizable Word document.

A copy of the OSHA Occupational Noise Exposure Standard (29 CFR 1910.95) is available through EHS or the EHS web page at .

Click here for Links to Noise and Hearing Conservation web sites.

The following references are available through EHS:

    • Noise Control: A Guide For Workers And Employees, edited by Richard L. Stepkin and Ralph E. Mosely, American Society of Safety Engineers, 1984
    • Noise Control in the Workplace, Aspen Systems Corporation, 1978
    • Industrial Noise Manual, American Industrial Hygiene Association, 1975

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