Suppression of evoked otoacoustic emissions by contralateral noise exposure in humans

The effects of contralateral noise exposure on evoked otoacoustic emission (e-OAE) were investigated in 10 normal hearing subjects and 3 cases with unilateral deafness. The e-OAE was recorded by ILO88 and weighting noise was given to the contralateral ear (impaired side in unilateral deafness cases). The air conducted noise exposure showed suppressive effect on e-OAE along with the increase of noise stimulus intensity in normal hearing subjects, but did not in unilateral deafness cases. The degree of suppression in e-OAE was most remarkable in highest peak power between 1 kHz and 2 kHz in FFT picture and the mean value of maximal suppression in 10 normal hearing subjects was 2.2 dB. The bone conducted noise exposure showed no effects on e-OAE in either normal hearing subjects or unilateral deafness cases. It was suggested that the contralateral noise exposure could suppress the function of cochlear micromechanics probably via crossed olivocochlear bundle.