Evaluation of Safe Exposure Guidelines for Moderate and High Intensity Continuous Noise.
Technical rept. 1 Feb 75-31 Jul 76,
DAYTON UNIV OH RESEARCH INST
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The TTS2 temporary threshold shift measured two minutes after noise termination consequences of brief noise exposures were systematically evaluated. Specifically, forty subjects were tested at each of 10 appropriately spaced noise exposure levels. The 90th percentile TTS2 at 4000 Hz was determined for each exposure level and then a multiple regression equation was fitted to these values. From this equation, a 5 dB equal 90th percentile TTS2 curve was calculated, which represents the authors predictions as to the trade-offs between noise intensity and exposure duration necessary to produce 90th percentile TTS2s of 5 dB. A comparison of the authors predictions to those of the Environmental Protection Agency EPA in the area of uncertainty suggests that the conservative EPA predictions may be too conservative while the EPAs modified and extended National Research Council Committee on Hearing, Bioacoustics, and Biomechanics CHABA criterion predictions may not be sufficiently conservative. Although the authors predictions reflect the trends which were actually observed in the present investigation, it would be unreasonable to assume that the authors predictions are more than ball park estimates of reality.
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