Efferent control of the human auditory system

he effects of auditory efferent activity on peripheral physiology may be examined by presenting broadband noise (BBN) to the contralateral ear during otoacoustic emission (OAE) recordings. The presentation of BBN typically produces a reduction of OAE amplitudes in comparison to a condition without BBN. This is termed contralateral suppression. Limited information exists regarding the effects of contralateral BBN on responses observed at higher levels in the auditory system. The present study employed this paradigm to investigate interactions of attention and laterality on the transient evoked otoacoustic emission (TEOAE), auditory brainstem response (ABR) and cortical auditory evoked potentials (CAEP) P1-N1-P2. TEOAEs were evoked by 60 dB SPL clicks; ABRs and CAEPs were evoked by 60 dB SPL 2.0 kHz tone pips in 15 normally hearing adults. Four conditions were employed for each ear: (1) quiet (no noise); (2) 60 dB SPL contralateral BBN; (3) words (at -3 dB SNR) embedded in 60 dB SPL contralateral BBN while subjects classified words as animal versus food items; (4) words from condition...