Today, audiologists have many tools at their disposal to help identify and assess hearing loss.
Otoacoustic emissions (OAEs) are clinically important because they are the basis of a simple, non-invasive, test for hearing defects in newborn babies and in children who are too young to cooperate in conventional hearing tests. An otoacoustic emission test measures an acoustic response that is produced by the inner ear (cochlea), which in essence bounces back out of the ear in response to a sound stimulus. The test is performed by placing a small probe that contains a microphone and speaker into the ear. As the patient rests quietly, sounds are generated in the probe and responses that come back from the cochlea are recorded. Once the cochlea processes the sound, an electrical stimulus is sent to the brainstem. In addition, there is a second and separate sound that does not travel up the nerve, but comes back out into the ear canal. This “byproduct” is the otoacoustic emission. The emission is then recorded with the microphone probe and represented pictorially on a computer screen. The audiologist can determine which sounds yielded a response/emission and the strength of those responses.
OAEs can be recorded on people at virtually any age, from shortly after birth to well above age 80. For example, research has shown that babies with normal hearing have measurable OAEs as soon as six hours after birth.