自由音場と拡散音場における騒音暴露によるTTSの比較

概要

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In order to investigate whether the different sound field causes difference in temporary threshold shift(TTS), ten young students with normal hearing acuity were exposed to broadband noise for an hour both in an anechoic room(free-field) and in reverberant room(diffuse-field). In the anechoic room, one subject was exposed to the noise faced with his right ear directly to the speaker, and in the reverberant room, two subjects were exposed at a time. The exposure noise was the white noise band-pass-filtered from 0. 9kHz to 9kHz, and the exposure levels were 80, 83, 86 and 89dB SPL, which were the same in the both field when measured by means of 1-inch free-field microphone. TTSs were measured at 2, 3, 4, 6 and 8kHz. The results showed that no significant TTSs were observed at 2kHz in either field. The growth curves of TTS at 3 and 4kHz observed in both fields were similar. However, TTSs at 6 and 8kHz in free-field exceeded those in the diffuse-field. It is estimated from the present study that the sound pressure level in the diffuse-field measured by means of the free-field microphone needs to be raised by 2. 7dB so that the TTSs at 8kHz in the both fields might be equal. Those results are consistent with the sound pressure level transformations from both sound fields to the coupler microphone of an anthropometric manikin(KEMAR manikin).
社団法人日本音響学会の論文
1985-04-01