청각시스템(auditorysystem)은 음향자극이와우(cochlear)에서 청각피질(auditory cortex)에 이르는 구심성 전달경로(afferent pathway)와 반대로 청각피질에서 와우에 이르는 원심성 전달경로(efferent pathway)로 이루어져 있다. 이 중 구심성 전달경로에 대한 연구는 동물이나 인 간에 있어서 광범위하게 이루어져 왔으나, 원심성 전달경로는 아직도 밝혀내야 할 부분이 많이 있다. Rasmussen(1946)21)에 의해 메커니즘이 밝혀진 올리브와우삭(olivocochlearbundle) 은 상올리브복합체(superior olivary complex)의 내측에 위치해 있는 내측 올리브와우삭(medial olivo-cochlear bundle, 이하 MOCB)과 외측에 위치해 있는 외측 올리브와우삭(lateral olivo-cochlear bundle, 이하 LOCB)으로 이루어져 있다. MOCB은 직경이 LOCB보
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. KEY WORDS：MOCB·Efferent system·TEOAE suppression.
INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSIONS CONCLUSIONS REFERENCES
