It is important to identify hearing loss as early as possible. Ideally this means no later than 6 months of age. Hearing loss often is discovered when a child is being evaluated for difficulty with school performance or behavior. Even slight hearing loss in one ear can impact a child's speech and language development.
The doctor will ask about your child's medical history. He will perform a physical examination and look closely at your child's ears. The doctor looks for:
Deformities of the ear
Problems with the eardrum (including signs of middle-ear infection)
Accumulation of earwax
Objects in the ear
Various tests can be done to measure hearing loss, including:
Tympanogram — This is a screening test for middle ear problems. It measures the air pressure in the middle ear and the ability of the eardrum to move.
Audiometry — This test is used to determine the volume of sound the child can hear. The child listens to sounds of various volume and frequency through earphones in a soundproof room. Children are asked to respond to the sounds by raising a hand. For younger children, the child responds to the sounds by playing a game. In children less than 2½ years old, audiometry is also used as a rough screening test to rule out significant hearing loss. An observer watches the infant's or toddler's body movements in response to sounds. This test cannot determine which ear has a problem or whether both do.
Auditory brain stem response (also called brainstem auditory evoked potential) — In this test, sensors are stuck to the scalp to record electrical signals from nerves involved in hearing. The signals are studied to give information about hearing and hearing-related brain function. This test is used to screen newborns or to test children unable to cooperate with other methods. It also can be used to confirm hearing loss or to give ear-specific information after other screening tests have been done. Young children often need to be sedated during this test so that their movements don't interfere with the recording.
Otoacoustic emissions — This is a relatively quick, noninvasive test. A miniature microphone is placed in the ear. It picks up signals that normally are emitted from the hair cells in the inner ear. This is an excellent screening test for all newborns. If a hearing problem is found, it should be confirmed with the auditory brain stem response test.
Testing is done routinely for infants and children at high risk of hearing loss. These include children who have:
Developmental delays, especially in speech
Syndromes involving the head that are associated with hearing loss
Other risk factors, such as a history of premature birth or bacterial meningitis or a family history of hearing loss
Many hospitals now automatically screen all newborns for hearing loss. Your newborn baby should have a hearing screen done in the nursery before discharge. Ask for the results. If your baby does not pass the screening test, a specialist should evaluate your child's hearing as an outpatient.