AUDITORY EFFERENTS INVOLVED IN SPEECH-IN-NOISE INTELLIGIBILITY

FOLLOWING studies proposing that medial olivocochlear efferents might be involved in the processing of complex signals in noise, we tested t he involvement of efferent feedback in speech-in-noise intelligibility . Two approaches were used: measures of speech-in-noise intelligibilit y in vestibular neurotomized patients with cut efferents and compariso n with normal hearing subjects; and correlations between effectiveness of olivocochlear feedback, assessed by contralateral suppression of o toacoustic emissions and speech-in-noise intelligibility in normal sub jects. Contralateral noise improved speech-in-noise intelligibility in normal ears. This improvement, which was almost absent in de-efferent ed ears of vestibular neurotomized patients, was correlated with the s trength of the olivocochlear feedback. Together, these results suggest that olivocochlear efferents play an anti-masking role in speech perc eption in noisy environments.