在三种中等强度噪声下暴露60天豚鼠的听阈偏移及其恢复特征

本文观察豚鼠在85、90、95 dBA 三种中等强度噪声下暴露60天的听阈偏移及其恢复过程。实验期15～30天,95dBA 组的听阈偏移迅速增加并达到最大值。而后稳定在20dB 左右。85和90dBA 组的听闭偏移差异很小。实验期为60天时,两组的偏移基本相等,约9dB。噪声暴露结束后21天内,95dBA 组保持18～20dB 的偏移水平,而后逐渐减少,但75天后不再继续恢复,大约维持在12dB 左右的偏移水平。90dBA 组,听力的恢复较为缓慢,30天后仍有7dB 的偏移。而85dBA 组,暴露后21天内,恢复较快,30天后停止恢复,保持在3～4dB 的偏移水平。

HEARING THRESHOLD SHIFT AND ITS CHARACTERISTICS UNDER A 60-DAY EXPOSURE TO BROADBAND NOISE AT THREE MODERATE LOVEIS

The purpose of this experiment was to study the rule and characteristics of hearing threshold shift in guina pigs during a period of 60-day exposure(8h/day) to three moderate levels of noise(85,90 and 95 dBA).For 95-dBA group,the threshold shift rapidly increased and reached maximum between 15th and 30th test days,and thereafther became stationary within a range of 20-30 dB.within twenty-one days after the exposure,the threshold shift kept at a level of 18-20 dB,and thereafter,gradually decreased till 75th day after the exposure,then maintained a level of about 12dB.For 90-and 85-dBA groups,the threshold shifts, 8.4 and 8.6dB respectively,were quite close at the end of exposure,but for 85- dBA group the recovery of the threshold shift was faster within 21 days postexposure.