The other kind of ear-produced sound, evoked otoacoustic emissions, is similar to echoes, generally somewhat distorted from the original sound.

Another screening device uses an ear probe to record "evoked otoacoustic emissions" - tiny sounds made by cochlea hair cells when they are stimulated.

Newborn hearing testing is done at the bedside using transiently evoked otoacoustic emissions, automated auditory brainstem responses or a combination of both techniques.

Broadly speaking, there are two types of otoacoustic emissions: spontaneous otoacoustic emissions (SOAEs), which can occur without external stimulation, and evoked otoacoustic emissions (EOAEs), which require an evoking stimulus.

Two approaches are commonly utilized that increase the unfavorable signal-to-noise ratio and facilitate extraction of the OAE waveform: transient evoked otoacoustic emission (TEOAE) and distortion product otoacoustic emission (DPOAE).