A hearing test is easy and painless. Doctors use one of two measures: an otoacoustic emissions (OAE) test, which measures the response by the hair cells inside the ear when they're stimulated by sound, or an auditory brain-stem response (ABR) test, which measures brain-wave activity in response to sound. Both of these tests are given while the baby is asleep, and for babies, they're both pass or fail: They only tell doctors if a baby can hear 30 decibels (the sound of a whisper), which is the definition of normal hearing. If your baby fails the initial screening test, you need to make an appointment with an audiologist for more comprehensive testing in order to confirm the results, determine the severity of the loss, and get proper treatment.
You can't count on your baby's doctor to identify a problem -- most pediatricians don't have the proper equipment to do infant hearing tests in their offices. Before you give birth, check with your hospital to make sure that hearing testing is part of their newborn screening process. If it's not, or if you give birth somewhere other than a hospital, ask your pediatrician to recommend a pediatric audiologist or otologist to screen your baby within her first three weeks. Hearing tests for newborns are mandatory in 42 states and in Washington, D.C. (although small hospitals may be exempt). However, every baby's hearing should be tested at birth so that parents can get help quickly if there's a problem. Testing is especially crucial because research has shown that parents' impressions about their infant's hearing are often wrong. Even deaf babies can coo and make gurgling sounds. If you're not sure whether your baby has been tested, contact your hospital to check her records. --Ilisa Cohen
Originally published in the May 2007 issue of Parents magazine. Updated 2009