Relation Of Structural Damage To Exposure Time And Intensity In Acoustic Trauma

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Abstract
In order to overcome the difficulty to obtain a survey evaluation of the entire cochlea as well as an ultrastructural examination of selected areas of the same ear, we used a new technique for combined surface preparations and EM studies without the risk of damage by mechanical preparation. Exposure intensities were varied from 100 to 140 dB and exposure times from 30 sec to one week. The relations between exposure time and extent or type of damage on one hand and between exposure intensity and damage on the other hand were worked out at different intensity levels. Above 120–130 dB exposure intensity, direct immediate structural damage occurs regularly in various degrees, depending mainly on exposure intensity, whereas in lower intensities delayed phenomena are predominant, depending mainly on exposure time.