Christophe Micheyl
Lionel Collet
Lab. Phys. Sens. Audition et Voix, URA CNRS 1447, Pavillon U. Hopital E. Herriot, 3, Pl. d'Arsonval, 69437 Lyon Cedex, France
In order to investigate the potent role of the efferents in perception in noise, medial olivocochlear feedback and signal-in-noise detection abilities were both examined in 30 normally hearing subjects. Medial olivocochlear feedback was assessed in terms of reduction in click-evoked otoacoustic emission amplitude under a contralateral acoustic stimulation consisting of a 30-dB SL broadband noise. Monaural detection thresholds of 1- and 2-kHz tones embedded in broadband noise were measured with and without the same contralateral stimulation sucessively. The finding of a correlation between the reduction in otoacoustic emission amplitude and the detection threshold of the 2-kHz tone in the presence of the contralateral stimulation suggests that the detection abilities are partly related to the operation of the medial olivocochlear feedback. The results indicate moreover that in these subjects with the strongest medial olivocochlear feedback, the detection performance is improved by the addition of noise in the opposite ear whereas it decreases or remains constant in the other subjects.