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Damage-risk contours for intermittent noise exposures.

Authors
Ward-WD
Source
NIOSH 1977 Aug; :1-21
Link
NIOSHTIC No.
00082913
Abstract
NIOSH-sponsored research was conducted on the development of contours that would specify equal risk for intermittent noise exposures. A total of about 300 different exposures to steady and intermittent broad, narrow, and octave band noises were given to 10 young normal listeners. A complete preexposure audiogram at half octave intervals was administered to each subject before the exposure and 16 hours after its termination. Results indicate that: 1) exposures need not be quite 8 hours long to give valid results; 2) for octaves except 2000 and 4000Hz, reducing exposure by means of intermittency cuts the amount of temporary threshold shift (TTS) down so drastically that even the 5dB exposure rule is over conservative; 3) effective quiet levels were about 76dB for octave bands at and below 500Hz, and around 68dB at 1000Hz and above; 4) contours defining SPLs that produced 10 or 20dB of TTS2 after an 8 hour exposure were not as flat as the 0dB TTS2 contour; 5) not all hazardous real life noises have a constant spectrum, although most do; 6) even in the exposure with the greatest disparity among levels, the TTSs at 500 and 1400Hz were identical to those produced by steady 90dBA noise; 7) burst duration varies in actual work situations; 8) intermittency of noise reduces noise hazards; 9) alcohol appears to pose no synergistic threat to the hearing of workers in noisy industries; and 10) testing produced no significant alterations in the subjects' hearing.
Keywords
NIOSH-Grant; Hearing-tests; Environmental-control; Exposure-limits; Long-term-exposure; Noise-control; Sensory-perceptual-processes
Contact
Otolaryngology U of Minnesota Box 461 Mayo Minneapolis, Minn 55455
Publication Date
19770831
Document Type
Final Grant Report
Funding Amount
290004
Funding Type
Grant
Fiscal Year
1977
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-00350
NIOSH Division
OEP
Source Name
Department of Otolaryngology, University of Minnesota, Minneapolis, Minnesota, Terminal Progress Report, NIOSH Grant No. R01-OH-00350, 21 pages, 10 references
State
MN
Performing Organization
University of Minnesota Minneapolis, Minneapolis, Minnesota
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