Testing Baby's Hearing

How early should your child's hearing be tested? Soon after birth, according to the nation's hearing and communication experts

If that answer surprises you, consider this: Every year, about 12,000 babies in this country are born with hearing problems. Many of these children will not be diagnosed and treated until after they are 2 years old. By then, they will have missed out on key years of stimulation of the hearing centers in their brains. As a result, they may have problems developing speech and language skills that could affect them the rest of their life, especially in school or at work.

Early detection, follow-up and treatment of hearing problems in newborns, however, can prevent many of these communication problems, the National Institute on Deafness and Other Communication Disorders (NIDCD).

All newborns should be screened in the hospital or birthing center before they are discharged, the NIDCD says. Many states currently require, by law, hearing screenings for newborns, just as they require screening tests for phenylketonuria, hypothyroidism and other diseases.

Test by 3 months

Ideally, infants should be tested before they are 3 months old, so that treatment can begin before 6 months of age -- the crucial period in a baby's life for speech and language development, the NIDCD says.

Several methods are used for newborn screening, including auditory brainstem responses (ABR) and otoacoustic emissions (OAE). Both tests are painless and take only minutes to administer.

In the ABR test, sound is introduced to the baby's ears through tiny headphones while the baby is sleeping. Three small discs placed on the baby's head measure whether the baby's brain is detecting the sounds. The whole process takes about 5 minutes if the baby is quiet and cooperative.

The OAE test works differently. OAEs are very faint but detectable sounds produced by most normal ears. Although a person cannot hear his or her own emissions, tiny sensitive microphones placed in the ear canal can measure the sounds. During the OAE screening, sound is introduced through a small flexible probe inserted into the sleeping baby's ear. A microphone inside the probe detects the emissions produced by the baby's ear in response to the sound. No emissions are detected from an infant who cannot hear.