What is Otoacoustic-Emissions Testing?

Hearing aids can take an individual from a life of isolation to a life of socialization. Many of the 48 million Americans suffering from hearing loss tend to avoid situations where it is difficult to hear, such as parties, restaurants or concerts. This avoidance can lead to isolation and depression, not to mention the fact that undiagnosed hearing loss can also lead to brain and memory atrophy.

Because of the additional consequences of hearing loss, it is important for individuals who think they have hearing loss to make an appointment with a hearing healthcare professional, such as an audiologist. An audiologist is a hearing healthcare specialist who studies hearing, balance and other related disorders. Audiologists are able to diagnose and treat individuals with hearing loss.

Different types of tests

During your appointment with an audiologist, you will undergo a variety of hearing evaluations. There are many types of hearing tests, including a whispered-speech test, pure-tone audiometry, tuning-fork test, speech-reception and word-recognition tests, auditory-brain-stem testing and otoacoustic-emissions (OAC) testing.

OAC testing

A common test used by audiologists is OAC-emissions testing. According to the American Speech-Language-Hearing Association (ASHA), OAC emissions are sounds emitted by the ear when the cochlea — the spiral cavity of the inner ear — is stimulated by sound. As the cochlea is stimulated, the outer hair cells of the ear vibrate, producing a quiet, almost inaudible sound, which echoes to the back of the middle ear.

People who do not have hearing loss produce normal emissions. Individuals with hearing loss greater than 25-30 decibels do not produce these sounds.

How it is performed

OAC-emissions tests are performed by placing a small and flexible probe, which includes a microphone, into an ear. The microphone detects the OAC emissions.  Along with testing for OAC emissions, the test also detects potential blockages in the outer ear canal, any middle ear fluid and any damage to the outer hair cells in the cochlea.

Limitations and results

The OAC-emissions test has its limitations, however, as it cannot distinguish between conductive and sensorineural hearing loss. Because of these limitations, the test is usually a part of a battery of hearing evaluations you will likely undergo during an initial appointment with your audiologist.

The results of the test, in conjunction with those from other tests, will help the audiologist determine the degree of hearing loss you suffer from. With this information, they can begin recommending hearing aids or other devices to enhance your hearing.