A brainstem auditory evoked response (BAER) test measures how your brain processes the sounds you hear. The BAER test records your brainwaves in response to clicks or other audio tones that are played for you. The test is also called a brainstem auditory evoked potentials (BAEP) or auditory brainstem response (ABR) test.
A BAER test can help to diagnose hearing loss and nervous system disorders, especially in newborns, young children, and others who may not be able to participate in a standard hearing test. BAER tests are often administered to canines and are the only scientifically reliable way to test a dog’s ability to hear with one or both ears.
BAER tests are quick and easy and have virtually no risks or complications; you don’t even have to be awake while the test is being performed. You do not need to prepare for the test in advance, though you may be asked to wash your hair the night before to remove oils that might keep the testing equipment from sticking to your scalp.
You will simply lie back in a reclining chair or on a bed and keep still while the doctor places small electrodes (sticky patches with wires attached) on your scalp and earlobes. The electrodes are connected to a machine that records your brain activity. If your infant or child is being tested and cannot remain still, the doctor may give him or her a sedative medication.
The doctor will then give you a set of earphones. You should hear a series of clicks or tones played through the earphones, but you do not need to do anything in response to the sounds. The electrodes placed on your scalp and earlobes will record how your brain reacts to the noises you hear. It will show if you are hearing the sounds properly and if they are being conducted from your ears to your brain.
A printout of your test results should show spikes in your brain activity each time you heard one of the clicking sounds or other tones. If your results are in more or less a flat line, it may indicate that you have hearing loss.
Abnormal test results can also indicate that you have sustained damage to your brain or nervous system. This could be caused by:
- multiple sclerosis (an autoimmune disease that causes damage to the protective coverings of your nerve cells)
- central pontine myelinolysis (another condition that damages the myelin sheath covering your nerve cells)
- acoustic neuroma (a tumor growing on the nerve that connects your ear to your brain)
- a stroke
- a brain injury
- a brain tumor
- a speech disorder
If your test results are abnormal, additional tests will probably be required to determine the cause. Once the underlying cause has been identified, your doctor will discuss your treatment options with you.