Effects of the conditioning click on click-evoked otoacoustic emission

The effects of the preceding (conditioning) click on the evoked otoacoustic emission (EOAE) to the following (test) click were investigated in normally hearing adults. To overcome distortions due to superimposition of the test EOAE on the EOAE to the conditioning click, a special stimulation and response subtraction procedure was utilized. The conditioning stimulus was found to suppress the test EOAE. The suppression lessened with a decrease in the conditioning stimulus level and an increase in the time interval between the conditioning and the test stimuli. Nevertheless, the influence was traced even with the level of the conditioning stimulus as low as 5 dB SL, and lasted for the interval between the conditioning and the test stimuli, as long as 7.5 ms. An attempt at theoretical comprehension of the obtained results is made and their usefulness in differentiation of EOAEs from acoustic reflections is proposed.