Involvement of the Efferent Auditory System for Improvement in Speech Perception in Noise

Vijaya Kumar Narne, Mohan Kumar Kalaiah


To investigate the involvement of auditory efferents in hearing-in-noise in humans, Median olivocochlear (MOC) efferent’s functioning and speech recognition-in-noise abilities were compared in 19 subjects. MOC efferent’s function was assessed in terms of contralateral attenuation of transient evoked otoacoustic emissions (TEOAE): i.e., the reduction in TEOAE amplitude elicited by a 40, 50 and 60-dB SPL contralateral speech spectrum shaped noise. Correspondingly, the speech reception thresholds for sentences embedded in 50-dB SPL speech spectrum shaped noise (SRTn) were measured in the same ear as the TEOAEs, successively in the presence and in the absence of uncorrelated noise in the opposite ear at three different levels (i.e 40, 50, & 60 dB SPL). The results indicated there was no significant statistical correlation between the contralateral attenuation of TEOAEs and SRTn for uncorrelated noise. In addition, there was no change in SRTn for uncorrelated noise at different levels. These results were discussed in line with previous studies.


OAE, Contralateral suppression, uncorrelated noise, speech perception.

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