f. During noise surveys, inventories of hazardous noise areas are usually kept.
Records of noise surveys are kept on DD Form 2214 (Appendix H). Risk assessment
codes are assigned for all sound levels above 85 dB (A).
3-10. HAZARDOUS NOISE STANDARDS
a. Steady Noise -- Exposure Criterion. Levels of steady noise of 85 dB(A) or
greater are considered hazardous regardless of the duration of exposure for the
purpose of administering a hearing conservation program. Hearing conservation
measures must be initiated when personnel are exposed to levels 85 dB(A) or greater.
This criterion affords the advantage of increasing the overall efficiency of the program
by simplifying its administrative aspects and eliminating the requirement for dosimetry.
The dosimetry would determine a cumulative measure of varying noise levels and
exposure durations. It will also better protect those individuals who are more
susceptible to the effects of noise. Figures 3-2, 3-5 show examples of education
posters, which should be prominently posted in noise hazardous areas.
(1) Although the requirements of the program demand the initiation of
hearing conservation measures when levels are 85 dB(A) or greater, the
implementation of all available measures may not be necessary in every case. For
example, visitors to noise hazardous areas are required to wear hearing protective
devices, but the requirement for hearing evaluations does not apply to visitors.
(2) There may also be unique situations where noise levels rise infrequently
and unpredictably to 85 dB(A) or greater for short durations so that the wearing of
hearing protective devices may be judged impractical or unnecessary. Decisions to
waive the wearing of hearing protective devices or any other requirement of the
program must not be made arbitrarily. Such judgments may be rendered by trained
AMEDD personnel who will perform a thorough evaluation using approved
instrumentation and who will consider all factors relative to the potential for a given
exposure to cause hearing impairment.
b. Impulse Noise--Exposure Criterion. Levels that exceed 140 dB(P) are
considered hazardous. The measurement of impulse noise requires the use of special
instrumentation and must be done only by specially trained AMEDD personnel. All
small arms used by the Army produce impulse noise levels above 140 dB(P). Hearing
conservation measures must be instituted and enforced when firing weapons during
training. Impulse noise between 120 and 140 dB(P) may be uncomfortable and the
wearing of hearing protection may be advisable. Repeated exposure to levels
exceeding 100 dB(A) can result in significant hearing loss.
3-11. ENGINEERING CONTROL MEASURES
The environmental control of noise exposure may involve the solution of complex
noise reduction problems. Many such projects should be undertaken only with the help
of acoustical engineers or consultants in noise control.