Otoacoustic emissions (OAS)

Table of Contents:

  1. What are otoacoustic otoemissions?
  2. What does it consist of?
  3. Why is it performed?
  4. Preparing for otoacoustic emissions
  5. What does the test feel like?
  6. What abnormal results mean

What are otoacoustic emissions?

Otoacoustic emissions (OAE) are tests to diagnose the patient’s hearing status.

OAEs are sounds originating in the cochlea, produced by its own activity and as a result of the movement of the hair cells of the organ of Corti. It is a test performed mainly on newborns to detect hearing loss early.

Otoacoustic emissions are a test to diagnose hearing status.

What does it consist of?

Otoacoustic emissions can be of different types:

  • Spontaneous otoacoustic otoemissions. These are sounds produced by the cochlea due to the absence of external stimulation.
  • Otoacoustic emissions provoked. These are the OAEs that are generated in response to a stimulus. According to the characteristics of the stimulus they are:
    • Transient otoemissions. Emissions provoked by a brief acoustic stimulus, usually a click. They detect cochlear damage and also for early diagnosis of hearing loss or deafness.
    • Continuous otoemissions. These are emissions in response to two simultaneous tones of different frequencies. They are used for early detection of mild cochlear damage, which cannot be observed in conventional audiometry.

Otoacoustic emissions are objective tests that are performed quickly, easily and non-invasively, and are therefore very focused on pediatrics. They allow early detection of hearing loss in infants.

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Why is it performed?

As we have already mentioned, it is a clinical test to diagnose early hearing loss in young children. It is an objective test that does not require the direct collaboration of the patient.

In adults, otoacoustic emissions allow an exploration of the auditory canal up to the cochlea, including the auditory nerve, so that we can confirm the patient’s hearing status, whether he/she has a hearing loss and what type it is. In addition, these tests are performed to monitor hearing damage caused by ototoxic drugs, as well as the detection and prevention of damage in patients exposed to noise.

Preparing for otoacoustic emissions

It is advisable to perform the otoacoustic emissions test three to four days after the birth of the baby, before discharge from the hospital. In this way, the ear canal will be completely aerated and no detritus or solid debris will remain.

For the tests the child should be asleep, or awake and relaxed, and in a quiet room. Similarly, a soundproofed environment is also required for adult OAE. In addition, the patient should be seated or lying down comfortably and avoid making noises such as throat clearing, coughing or swallowing. He should minimize his movements, as well as maintain a slow breathing.

The patient should not have wax accumulation, liquids or solid residues in the ears, or have otitis.

What does the examination feel like?

The examination begins with the introduction of an acoustic probe, consisting of two microphones and a loudspeaker, into the ear canal, which will be performed by the ENT specialist. This is the most important part of the test, because the application and fitting of the probe will directly influence the correct measurement of the otoacoustic emissions. It must be performed carefully.

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The test is completely painless and quick. It usually takes one minute per ear. Depending on the child’s preparation and possible interruptions, the procedure may take up to 10 minutes.

Significance of abnormal results

In children, if the first test registers negative responses, the child is usually scheduled for a second test. It is not uncommon for the results to be 100% accurate.

The test can detect hearing loss or deafness in the infant, so treatment will consist of aural rehabilitation and implantation of hearing aids or cochlear implants if necessary.