An otoacoustic emission is a sound produced by the movement of the outer cochlear hairs in the mammalian cochlea. There are two types of otoacoustic emissions: Spontaneous Otoacoustic Emissions (SOAEs) and Evoked Otoacoustic Emissions (EOAEs). SOAEs occur spontaneously without an external stimulus, whereas EOAEs are produced when an external stimulus (e.g., two tones that stimulate nearby regions along the basilar membrane produce a distortion product at an intermediary frequency). Analysis of otoacoustic emissions can be used to diagnose diseases or damage of the ear.
