2000 年 10 巻 2 号 p. 72-77
It is known that the olivocochlear (OC) efferent fibers innervated to the outer hair cells (OHCs) can modulate the active process in the cochlea which is related to the motile response of the OHCs.The basic known effect of the activation of this OC efferent neurons is suppression of the auditory system. On the other hand, when tones are presented with background noise, the OC activation can enhance the responses of the auditory nerve.In the respect of the effective signal perception in the cochlea, the OC-system should not act during the signal perception in the background quiet, however, should be activated when the signals are perceived in the masking situation.In the present study, the practical role of this system is discussed by observing the effects of the severance as well as the stimulation of the OC-neurons on the auditory responses. The results obtained suggest that the OC system are not activated in the signal (short duration) perception in quiet. That is, in this situation, the benefit from the active mechanism is not disturbed by the OC efferent system. On the other hand, in the condition of the signal perception in the background continuous noise, OC system is activated effectively by the noise and can improve the perception of the newly presented signal in the cochlea.