EVOKED OTOACOUSTIC EMISSIONS AND AUDITORY SELECTIVE ATTENTION

The auditory system has an extensive peripheral efferent innervation. The question addressed in this paper is whether the olivocochlear bund le (OCB) efferent system innervating the outer hair cells (OHC) of the cochlea plays a role in selective attention. As evoked otoacoustic em issions (EOAE) provide a measure of the active micromechanical propert ies of OHCs. they can be used to assess the role of the efferent syste m in attention. Six experiments using tone-pip EOAEs are reported, In each experiment, EOAEs generated by 1 or 2 kHz tone pips when they wer e attended were compared with EOAEs to the same stimuli when they were unattended. In three experiments (1-4), a non-linear stimulus differe nce method was used to record a pure cochlear component of EOAEs. In E xps. 1-5, 1 and 2 kHz tone pips were delivered to the same ear and the difficulty of the subjects' task was manipulated in order to produce a more focussed attentional state or contralateral noise was presented to determine whether attention effects are dependent upon having an a lready activated efferent system. In Exp. 6, the 1 and 2 kHz stimuli w ere delivered to opposite ears. A total of 70 subjects participated in the six experiments. There were no effects of attention on EOAEs in a ny of the experiments in the direction of previously reported effects. The results of these first six experiments employing simple attention switches between fixed auditory objects do not support active cochlea r involvement in selective attention.