[Acoustic oto-emissions: the ear emits sounds]

Otoacoustic emissions are sounds emitted by the inner ear. Their genesis requires the outer hair cells of the organ of Corti to be intact. Analysis of these sounds provides a fine evaluation of cochlear function. Evoked otoacoustic emissions (in response to a sound) are constant in subjects with normal hearing, whereas they always have pathological characteristics in patients with endocochlear conduction or perceptive deafness. When the acoustic nerve or the central nervous system are affected, otoacoustic emissions are normal for as long as the pathological process has no repercussions on the inner ear. This new functional exploratory method is of particular interest, being simple, non-invasive, rapid and objective. One of its main uses in adults is early detection of a lesion of the organ of Corti by e.g. ototoxic drugs or acoustic trauma. In children, it might become a test for objective detection of deafness, being easier to perform than evoked potentials of the brain stem.