Hearing Conservation

High noise levels can damage hearing, especially if these levels are experienced over a long period of time. The Occupational and Environmental Safety Office provides noise level surveys on an as requested basis, and when determined to be needed based on observation and inspection. If you have a noisy area, please feel free to call us for assistance in determining whether the levels are too high. Some suspect activities include construction noise, use of heavy equipment, working in machine rooms, and certain operations, such as sanding, grinding, and jackhammer.

OES has been contacted occasionally during construction activity outside which disturbs occupants of adjacent buildings. While these activities do not meet the OSHA criteria of excessive noise exposure, they can have an impact on the affected individuals. Any noise over normal background levels can interfere with speech, cause a stress reaction, lower morale, reduce efficiency, cause annoyance, interfere with concentration, and cause fatigue. Community noise levels in industrial areas are typically set at 61 dBA during the day. Administrators and managers should keep this in mind during periods of construction in adjacent areas.

A good source of information on noise and hearing conservation is the OSHA web site:
http://www.osha.gov/SLTC/noisehearingconservation/index.html

The following information was extracted from LSU’s Safety Manual:

Standards

Time-weighted average (TWA) noise limits as a function of exposure duration are shown as follows:

* No exposure to continuous or intermittent noise in excess of 115 dB(A).

** Exposure to impulsive or impact noise should not exceed 140 dB peak sound pressure level.

*** No exposure to continuous, intermittent, or impact noise in excess of a peak C-weighted level of 140 dB.

  • The OSHA regulation has an additional action level of 85 dB(A) which stipulates that an employer shall administer a continuing, effective hearing conservation program when the TWA value exceeds the action level. The program must include monitoring, employee notification, observation, an audiometric testing program, hearing protectors, training programs, and recordkeeping requirements.
  • The OSHA noise standard also states that when workers are exposed to noise levels in excess of the OSHA PEL of 90 dB(A), feasible engineering or administrative controls shall be implemented to reduce the workers’ exposure levels. Also, a continuing, effective hearing conservation program shall be implemented.

Effects

  • Auditory Effects
  • Chronic noise-induced hearing loss is a permanent sensorineural condition that cannot be treated medically. It is initially characterized by a declining sensitivity to high-frequency sounds, usually at frequencies above 2,000 Hz.
  • Exposure of a person with normal hearing to workplace noise at levels equal to or exceeding the PEL may cause a shift in the worker’s hearing threshold. Such a shift is called a standard (or significant) threshold shift and is defined as a change in hearing thresholds of an average 10 dB or more at 2,000, 3,000, and 4,000 Hz in either ear. Workers experiencing significant threshold shifts are required by 29 CFR 1910.95(g)(8) to be fitted with hearing protectors and to be trained in their use.
  • Extra-auditory Effects. In addition to effects on hearing, noise:
    • Interferes with speech;
    • Causes a stress reaction;
    • Interferes with sleep;
    • Lowers morale;
    • Reduces efficiency;
    • Causes annoyance;
    • Interferes with concentration; and
    • Causes fatigue.
  • Noise/Hearing Loss
      • Noise-induced loss of hearing is an irreversible, sensorineural condition that progresses with exposure. Although hearing ability declines with age (presbycusis) in all populations, exposure to noise produces hearing loss greater than that resulting from the natural aging process. This noise induced loss is caused by damage to nerve cells of the inner ear (cochlea) and, unlike some conductive hearing disorders, cannot be treated medically.36 While loss of hearing may result from a single exposure to a very brief impulse noise or explosion, such traumatic losses are rare. In most cases, noise-induced hearing loss is insidious. Typically, it begins to develop at 4000 or 6000 Hz (the hearing range is 20 Hz to 20000 Hz) and spreads to lower and higher frequencies. Often, material impairment has occurred before the condition is clearly recognized. Such impairment is usually severe enough to permanently affect a person’s ability to hear and understand speech under everyday conditions. Although the primary frequencies of human speech