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 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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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
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:
HEARING PROTECTION MUST BE WORN WHEN
THIS EQUIPMENT IS IN OPERATION
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.
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
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
Persons enrolled in the Audiometric Testing Program must have a termination
audiogram upon leaving Princeton University.
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
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
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
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
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.
- 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
- 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 http://www.princeton.edu/~ehs/services.htm#noise
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
- Noise Control in the Workplace, Aspen Systems Corporation,
- Industrial Noise Manual, American Industrial Hygiene Association,
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