Effects of Contralateral Stimulus on the Transient Evoked Otoacoustic Emissionsin Normal Hearing

Effects of Contralateral Stimulus on the Transient Evoked Otoacoustic Emissions in Normal Hearing Soo-Jin Cho, So-Hyun Cho and Mi-Jung Choi Department of Speech Pathology & Audiology, Department of Public Health Graduate School, Daebul University, Yeongam, Korea During measurements of transient evoked otoacoustic emission (TEOAE), acoustic stimulation of the contralateral ear reduces or suppresses TEOAE amplitude. This is thought to be due to the inhibitory control that the medial olivo-cochlear bundle (MOCB) exerts on the outer hair cell function. The purpose of this study was to investigate effects of contralateral stimulus on TEOAE. Contralateral suppression of TEOAE using four types of stimulus was measured in 30 young adults (30 ears) with normal hearing at 30, 40, 50 dBSPL. Contralateral stimuli were broad band noise (BBN), narrow band noise (NBN), amplitude modulation (AM) and frequency modulation (FM). This study showed that TEOAE suppression using contralateral noises increased orderly AM, FM, NBN and BBN at 40 and 50 dBSPL. Except for BBN, there was no significant difference between NBN, AM and FM. And as contralateral noise levels from 30 dBSPL to 50 dBSPL increase, TEOAE suppression also increased. But there was no the effect of gender. These results indicated that OAE represented a means of functional exploration of the active micro-mechanical properties of OHCs and our study was meaningful in the light of indicating amplitude fluctuation and frequency bandwidth effects in MOCB activation.