The Combined Effects of Vibration, Noise, and Exposure Duration on Auditory Temporary Threshold Shift
Final rept. Jul 1972-Mar 1973
AIR FORCE AEROSPACE MEDICAL RESEARCH LAB WRIGHT-PATTERSON AFB OH
Pagination or Media Count:
To determine the combined effects of noise and vibration on auditory function, the temporary threshold shifts TTS of two groups of 10 subjects each were measured as a function of intensity and duration of exposure. Combined noise and vibration was presented to one group for 5 minutes and to the other for 20 minutes. Both groups were exposed to vibration in the Z axis at frequencies of 9 Mz and 18 Hz at intensity levels of 0.475 gz peak and 0.950 gz, respectively. Noise levels of 90 dB and 100 dB were presented simultaneously with the vibration. TTS was measured at post exposure recovery times of 0.5, 2.0, 5.0, 10.0, and 20.0 minutes. Although the mean difference was small 0.72 dB, a significantly larger TTS was obtained at 9 Hz than 18 Hz vibration, and 100 dB produced a larger TTS than 90 dB. Significant differences in TTS were also obtained as a function of duration of exposure, and as a function of post exposure recovery time.
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