Tones disappear faster in the right ear than in the left

In order to gain further information on the characteristics and physiologic al correlates of tone decay in humans, the tone decay test was administered to 58 normal-hearing subjects, successively in the left and right ears and in absence and presence of a contralateral noise. The results revealed tha t tone decay was greater in the right than in the left ear and was increase d by contralateral noise. The contralateral effect of this noise on cochlea r biomechanisms was then estimated by measuring contralaterally induced var iations in the amplitude of click-evoked otoacoustic emissions in the same subjects. In the right ear, the increase in tone decay and the decrease in otoacoustic emission amplitude-both induced by contralateral noise-were pos itively correlated (r = .315, p = .016). Furthermore, the contralateral cha nges in otoacoustic emission amplitude were found to be on average larger i n the right than in the left ear, this asymmetry being correlated with that observed for the tone decay. These findings are discussed in relation to p revious results on simple and induced loudness adaptation in the vicinity o f threshold, on contralateral attenuation of otoacoustic emissions and on t he influence of the auditory efferents on cochlear biomechanisms.