Olivocochlear efferent contributions to speech in noise recognition across signal to noise ratios.
The medial olivocochlear (MOC) efferent system modifies cochlear output to aid signal detection in noise, but the precise role of efferents in speech in noise understanding remains unclear. The current study examined the contribution of the MOC reflex for speech recognition in noise in 30 normal hearing young adults (27 females, mean age 22.7 yr) The MOC reflex was assessed using contralateral inhibition of transient evoked otoacoustic emissions. Speech in noise perception was evaluated using the coordinate response measure presented in ipsilateral speech shaped noise at signal to noise ratios (SNRs) ranging from 12 to 0 dB. Performance was assessed without and with the presence of contralateral noise to activate the MOC reflex. Performance was significantly better with contralateral noise only at the lowest SNR. There was a trend of better performance with increasing contralateral inhibition at the lowest SNR. Threshold of the psychometric function was significantly correlated with contralateral inhibition. Response time on the speech task was not significantly correlated with contralateral inhibition. Results suggest that the MOC reflex contributes to listening in low SNRs and the relationship between the MOC reflex and perception is highly dependent upon the task characteristics.
The Journal of the Acoustical Society of America