Otoacoustic emissions: an emerging diagnostic tool.

Otoacoustic emissions are acoustic signals detectable in the external auditory canal that reflect the state of health of the cochlea. Transiently-evoked otoacoustic emissions and distortion-project otoacoustic emissions are two types of otoacoustic emissions currently under investigation as well as in limited clinical use. These objective tests of cochlear function add significantly to the armamentarium currently in place for the evaluation of hearing. The clinical use of these diagnostic tools will likely increase dramatically in the coming years. The following review provides a basis for understanding the nature and clinical utility of otoacoustic emissions.