Brainstem auditory evoked response (BAER) is a test to measure the brain wave activity that occurs in response to clicks or certain tones.
How the Test is Performed
You lie on a reclining chair or bed and remain still. Electrodes are placed on your scalp and on each earlobe. A brief click or tone will be transmitted through earphones you are wearing during the test. The electrodes pick up the brain's responses to these sounds and record them. You do not need to be awake for this test.
How to Prepare for the Test
You may be asked to wash your hair the night before the test.
Young children often need medicine to help them relax (sedation) so they can stay still during the procedure.
Why the Test is Performed
The test is done to:
- Help diagnose nervous system problems and hearing loss (especially in newborns and children)
- Find out how well the nervous system works
- Check hearing ability in people who cannot do other hearing tests
This test may also be performed during surgery to decrease the risk for injury to the hearing nerve and brain.
Normal results vary. Results will depend on the person and the instruments used to perform the test.
There are no risks associated with this test. There may be slight risks from having sedation depending on your age, medical conditions, and type of sedation medicine uses. Your provider will talk to you about any risk you may have.
Evoked auditory potentials; Brainstem auditory evoked potentials; Evoked response audiometry; Auditory brainstem response; ABR; BAEP
Hahn CD, Emerson RG. Electroencephalography and evoked potentials. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, eds. Bradley's Neurology in Clinical Practice. 7th ed. Philadelphia, PA: Elsevier; 2016:chap 34.
Kileny PR, Zwolan TA, Slager HK. Diagnostic audiology and electrophysiologic assessment of hearing. In: Flint PW, Francis HW, Haughey BH, et al, eds. Cummings Otolaryngology: Head and Neck Surgery. 7th ed. Philadelphia, PA: Elsevier; 2021:chap 134.
Wackym PA. Neurotology. In: Winn HR, ed. Youmans and Winn Neurological Surgery. 7th ed. Philadelphia, PA: Elsevier; 2017:chap 9.
Review Date 4/13/2020
Updated by: Josef Shargorodsky, MD, MPH, Johns Hopkins University School of Medicine, Baltimore, MD. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.