otoacoestische

Otoacoustic emissions, known in Dutch as otoakoestische emissies, are faint sounds produced by the inner ear and measurable in the external ear canal. They originate from the outer hair cells of the cochlea as a byproduct of sound-induced cochlear activity and can be detected with a sensitive microphone and a small probe inserted into the ear.

There are several types of otoacoustic emissions. Spontaneous otoacoustic emissions (SOAEs) occur without external stimulation and are present in a subset of individuals with normal or near-normal hearing. Evoked otoacoustic emissions (EOAEs) are elicited by brief or continuous sounds and include transient-evoked otoacoustic emissions (TEOAEs) and distortion-product otoacoustic emissions (DPOAEs). TEOAEs are generated by a transient stimulus, such as a click, while DPOAEs are produced by presenting two tones of nearby frequencies and measuring the resulting distortion products.

Clinical use and interpretation: OAEs are primarily used to assess outer hair cell function and cochlear status. They are a standard part of newborn hearing screening programs and are also used in audiology to monitor potential ototoxic effects, to differentiate cochlear from neural hearing loss, and to complement other audiometric tests. The presence of OAEs generally indicates functioning outer hair cells and some degree of usable cochlear reserve, whereas absent OAEs suggest outer hair cell dysfunction or conductive issues. However, OAEs do not measure hearing thresholds directly, and their absence can be affected by middle ear pathology, excessive noise, or age.

History: OAEs were first described after the discovery by David Kemp in 1978, revealing a non-invasive window into cochlear mechanics.