The bounce Event in Humans: Parameter Dependence

Alterations of click evoked otoacoustic emission (EOAE) after presentation of low-frequency loud tones were investigated in normally hearing subjects. The bounce phenomenon has objectively been studied thus. EOAE changes were manifested in initial augmentation and following reduction, peaked at 1 and 3 minutes of post-exposure time, respectively. Recoveries took 5-7 minutes afterwards. At lower exposure intensities augmentations exceeded reductions. At higher intensities symmetric EOAE modifications were observed. At highest intensity the obvious EOAE drop has hardly been preceded by any augmentation. Based upon these data, the bounce is considered to be a compound of two opposite events, appearance of each being dependent upon exposure intensity. Similar bounce magnitudes were found under linear and nonlinear EOAE acquisition modes. EOAE alterations were stated under ipsilateral but not contralateral exposures. It has been concluded therefore that the bounce involves peripheral receptor rather than central neural mechanisms. In special experiments the dependence of the bounce indices upon the exposure tone frequency and the test stimulus frequency and intensity has been investigated. No EOAE shifts were seen under isolated application of clicks. Correspondingly, the bounce was judged to reflect the active inner-ear processes but not regular test-stimulus presentation