TRANSIENT-EVOKED OTOACOUSTIC EMISSIONS AND CONTRALATERAL SUPPRESSION IN PATIENTS WITH UNILATERAL TINNITUS

Transient-evoked otoacoustic emissions (TEOAE) have been recorded from 20 patients with unilateral tinnitus and symmetrical hearing up to 20 00 Hz. Responses were digitally low-pass filtered al 2000 Hz. The func tion of the medial olivocochlear system (MOC) was examined by contrala teral acoustic stimulation (GAS) with broadband noise at 50 and 70 dB SPL. Emission amplitude was significantly lower in tinnitus ears in th e 10-15 ms part of the response. No difference in contralateral suppre ssion of amplitude could be found. The latency shifts were small and w ere not helpful in separating tinnitus from non-tinnitus ears. Analysi s on different parts of the response window may be a useful tool for s eparating tinnitus from non-tinnitus ears. The lack of efferent effect differences could result from influence of stimuli on tinnitus mechan isms.