Definition The brainstem auditory evoked response test, or BAER, helps evaluate:
hearing, or auditory, structures in the brain
how well a person hears
During this test, clicking noises stimulate the hearing nerves that run between the ear and the brain. Electrodes are attached to the scalp and ear lobes to record tiny changes in brain waves from these sounds. These changes appear on a graph as peaks, or highs, and troughs, or lows.
Because the response to BAER is involuntary, this test can:
check hearing in those who cannot respond or cooperate, such as babies, young children, and people in comas
help sort out whether certain hearing problems are physical or psychological
Who is a candidate for the test? The test may be done on newborns to check hearing. It may also be used when a person shows signs of:
How is the test performed? Usually the test takes less than 30 minutes. A doctor may perform the test in an office, clinic, or hospital. Often, a person sits up for this test. Dabs of ointment are applied at certain spots on the person's scalp and each earlobe. Electrodes are placed on these spots. As earphones deliver clicks to each ear, brain waves sensed by the electrodes are graphed.
What is involved in preparation for the test? People may be asked to wash their hair the night before the test. However, preparation for tests can vary. It is best to check with the staff where the test will be done for specific instructions.
What do the test results mean? The results of the test are compared to the results from people with normal hearing and brain function.
Fewer than normal peaks on a person's graph suggest disorders or damage to the hearing nerves.
Longer than normal delays between clicks and brain wave response suggest hearing loss due to a problem in the ear itself.
Author: Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
