Laroche C, Hétu R, Poirier S
Groupe d'Acoustique de I'Université de Montréal, Québec, Canada.
J Acoust Soc Am. 1989 Apr;85(4):1681-90. doi: 10.1121/1.397957.
It is now recognized that temporary threshold shift (TTS) grows to an asymptotic level (ATS) after a prolonged exposure to steady-state and intermittent noise. Few studies have been conducted to verify this process of acquisition for impact noise. However, results obtained on animals have demonstrated that an asymptote is reached after 1-2 h of exposure. These results have been confirmed in the present study on four human subjects using a 470-ms (B duration) impact noise at a rate of 1 pps. The above pattern of acquisition has been retested on two subjects exposed to the same impact for periods of 15-150 min. An ATS of 15-20 dB was measured (Lp = 102-104 dBA) after 30-60 min of exposure. Recovery curves were determined for each exposure duration. They appeared to follow a logarithmic function of post-exposure time. It took from 30-50 min for one subject and from 4-5 h for the other to completely recover. The time for total recovery did not seem to vary as a function of exposure time. Implications are drawn for damage risk criteria and for the study of the effects of impact noise on hearing.
现在已经认识到，在长时间暴露于稳态和间歇性噪声后，暂时性阈移（TTS）会增长到一个渐近水平（ATS）。很少有研究对冲击噪声的这一习得过程进行验证。然而，在动物身上获得的结果表明，暴露1 - 2小时后会达到一个渐近线。在本研究中，对四名人类受试者使用470毫秒（B时长）、每秒1次的冲击噪声，证实了上述习得模式。对两名受试者暴露于相同冲击15 - 150分钟的情况重新进行了测试。暴露30 - 60分钟后，测得的渐近阈移为15 - 20分贝（声压级Lp = 102 - 104分贝A）。确定了每个暴露时长的恢复曲线。它们似乎遵循暴露后时间的对数函数。一名受试者需要30 - 50分钟，另一名受试者需要4 - 5小时才能完全恢复。完全恢复的时间似乎并不随暴露时间而变化。对损伤风险标准以及冲击噪声对听力影响的研究具有启示意义。
