The aim of this study was to investigate the human peripheral auditory system in either ear to allow comparison of right and left medial olivocochlear inhibition during contralateral ear stimulation with a broad band noise. The efferent system showed a statistically significant greater right-side activity among 44 young subjects. This laterality appeared to be related to the presence of spontaneous otoacoustic emission but not to gender. This efferent asymmetry and the parallel spontaneous otoacoustic emission asymmetry could explain the lateralization of auditory sensitivity, temporary threshold shift and tinnitus.