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This study investigated whether visual attention affects the reliability (i.e., repeatability) of transiently evoked otoacoustic emission (TEOAE) magnitudes or of medial olivocochlear reflex (MOCR) estimates. TEOAEs were measured during three visual attentional conditions: control (subject were seated with eyes closed); passive (subjects looked at a pattern of squares on a computer screen); and active (subjects silently counted an occasionally inverted pattern). To estimate reliability, the whole recording session was repeated the next day. The results showed that visual attention does not significantly affect TEOAE or MOCR magnitudes—or their reliability. It is therefore possible to employ visual stimuli (e.g., watching a silent movie) during TEOAE experiments, a procedure sometimes used during testing to prevent subjects from falling asleep or to keep children still and quiet.

The medial olivocochlear (MOC) system is thought to be responsible for modulation of peripheral hearing through descending (efferent) pathways. This study investigates the connection between peripheral hearing function and auditory attention tasks of different degrees of difficulty. Peripheral hearing function was evaluated by analyzing the amount of change in otoacoustic emissions (OAEs) by contralateral acoustic stimulation (CAS), a well-known effect of the MOC system. Simultaneously, levels of attention were evaluated by event-related potentials (ERPs). The ERPs showed clear differences in processing tasks of different difficulty, but paradoxically there was no difference in the amount of OAE change brought about by CAS. There was also no effect on OAE latency, nor was there any difference in noise level or number of rejected trials. However, we observed that the changes in OAEs by CAS for easy and hard tasks were correlated with the magnitude of the P3 wave in the ERP. This suggests there might be some sort of mutual compensation mechanism - presently unknown - between periphery and cortex.