Otoacoustinc Emissions Test

The phenomenon of low-intensity sound signals emitted from the cochlea was first observed in the 1940s, but it wasn't until the late 1970s that these sounds were accurately measured with the invention of sensitive microphones capable of detecting such faint signals. Otoacoustic emissions (OAEs) are low-intensity sounds that can occur spontaneously or in response to an acoustic stimulus.

The detection of otoacoustic emissions in the ear provides insight into various aspects of hearing health. Primarily, OAEs indicate that the ear's sound transmission mechanisms are functioning correctly. They also confirm that the hair cells are operating normally, ensuring proper hearing sensitivity. OAEs are produced by the movement of outer hair cells within a healthy cochlea when stimulated by external sounds. These emissions can be measured using a specialized probe with built-in speakers and a microphone, which is inserted into the external auditory canal. OAEs serve as indicators of the integrity and function of the outer hair cells in the cochlea, offering valuable information about auditory health.

For accurate measurement of these faint sounds, a healthy outer and middle ear is essential, as the emissions can range from -10 dB SPL to +30 dB SPL in functioning ears.

It’s important to note that OAEs are not a hearing test and cannot determine the type or degree of hearing loss, as would be done with pure tone audiometry or auditory steady-state response (ASSR) testing. However, they are a crucial tool in both newborn hearing screening and diagnostic audiology, aiding in the differential diagnosis of various hearing conditions.

Otoacoustic emissions (OAEs) are valuable for diagnosing hearing loss associated with sensorineural damage, as they are produced in the cochlea. Additionally, OAE tests can detect conditions that disrupt sound transmission from the eardrums to the inner ears.