Distortion product oto-acoustic emissions

Otoacoustic emission is the energy leakage secondary to cochleartravelling wave transmitted through ossicular chain and tympanicmembrane to the external ear canal.This energy is biomechanical property of health functioning outerhair cells (OHCs) of the cochlea two main types of otoacoustic emissionshave been identified, spontaneous otoacoustic emission (recorded withoutextemal acoustic stimulus) and evoked otoacoustic emissions (EOAE)(recorded with external acoustic stimulus).The later type of emission is subclassified according to the evokingstimulus into :Transient evoked otoacoustic emISSIOn (TEOAE), stimulusfrequency otoacoustic emission (SFOAE) andDistortion products otoacoustic emission (DPOAE).Evoked otoacoustic emISSIOn (EOAEs) recording hold somepromise as a fast, objective and non-invasive audiological procedure tostudy the cochlea at the outer hair cell (OHC) level.