The influence of the efferent auditory system on otoacoustic emissions in noise induced tinnitus: clinical relevance.

This study demonstrates a clear relationship between noise induced tinnitus (NIT) and efferent neural auditory activity. The effect of contralateral white noise stimulation on click evoked otoacoustic emissions (CEOAEs) was studied in chronic tinnitus sufferers and controls, with and without a noise induced hearing loss (NIHL). For the non-tinnitus controls, increased contralateral white noise intensities resulted in decreased CEOAE amplitudes, irrespective of the hearing configuration. In contrast, the tinnitus patients responded with increased CEOAE amplitudes, particularly at lower contralateral noise intensities. While this was observed for both normal hearing and NIHL tinnitus patients, the effect was more pronounced amongst the normal hearing group. These findings were interpreted as reflecting a global efferent disorder in NIT patients, and are considered clinically relevant to the objective assessment of tinnitus.