较短时间声暴露后永久性听力损失的预测方法

THE INVESTIGATION OF PREDICTING METHOD ABOUT PERMANENT HEARING LOSS INDUCED BY SOUND EXPOSURE

50只豚鼠分为1个对照组和4个暴露组,分别暴露于1kHz纯音115,120,125和130dB(SPL)0.5h,观察暴露后的皮层听区电反应阀、琥珀酸脱氢酶(SDH)活性和毛细胞缺失率的变化。不同强度声暴露后0.5h内的平均听力损失<50dB者,不发生永久性听力损失,而>50dB者,则都有永久性听力损失。就单耳来说,大多数都符合这一关系。这一结果可为预测暴露后是否产生永久性听力损失提供参考依据。毛细胞SDH活性和表面形态无明显改变时,听力损失是暂时性的,酶活性下降明显但细胞形态尚属正常时,多数耳有永久性听力损失,当二者均有明显改变时,则几乎所有耳都留有永久性听力损失。

50 guinea pigs were randomly divided into a control and 4 exposed groups which were exposed to a pure toneof 1 kHz at 115,120,125,and 130 dB(SPL)respectively for a half hour.The changes of threshold of the cortical e-voked potential,the activity of succinic dehydrogenase(SDH)and the loss of outer hair cells were observed.Afterexposure,the cortical auditory potential threshold evoked by click rose in all animals.When the average hearingloss was<50 dB within 30 min,there was no permanent threshold shift(PTS).When the hearing loss was>50dB,there was PTS.The change in most individual ears accorded with this relation.The hearing loss was tempo-rary if there were no obvious change in SDH activity and morphology of outer hair cells.When the SDH activity re-duced significantly and the surface morphology of hair cells was normal yet,most ears had PTS.When both indiceschanged obviously there was PTS in almost all ears.