Hearing Evaluation in Children (continued)

Because there are characteristic waveforms for normal hearing in portions of the speech range, a normal ABR can predict fairly well that a baby's hearing is normal in that part of the range. An abnormal ABR may be due to hearing loss, but it may also be due to some medical problems or measurement difficulties.

Auditory steady state response (ASSR) test

An infant is typically sleeping or sedated for the ASSR. This is a new test that currently must be done in conjunction with the ABR to assess hearing. Sound is transmitted through the ear canals, and a computer picks up the brain's response to the sound and automatically establishes the hearing level. This test is still under development.

Otoacoustic emissions (OAE) test

This brief test is performed with a sleeping infant or an older child who may be able to sit quietly. A tiny probe is placed in the ear canal, then many pulse-type sounds are introduced and an "echo" response from the outer hair cells in the inner ear is recorded. These recordings are averaged by a computer. A normal recording is associated with healthy outer hair cell function and reflects normal hearing, although in some cases the hearing loss may be due to problems in other parts of the hearing pathway.

ABR or OAE tests are used at hospitals to screen newborns. If a baby fails a screening, the test is usually repeated. If the screening is failed again, the baby is referred for full hearing evaluation.

Tympanometry

Tympanometry is not a hearing test but a procedure that can show how well the eardrum moves when a soft sound and air pressure are introduced in the ear canal. It's helpful in identifying middle ear problems, such as fluid collecting behind the eardrum.

A tympanogram is a graphic representation of tympanometry. A "flat" line on a tympanogram may indicate that the eardrum is not mobile, while a "peaked" pattern often indicates normal function. A visual ear examination should be performed with tympanometry.

Who Performs Hearing Tests?

A pediatric audiologist specializes in evaluating and assisting kids with hearing loss and works closely with doctors, educators, and speech/language pathologists.

Audiologists have a lot of specialized training. They have master's or doctorate degrees in audiology, have performed internships, and are certified by the American Speech-Language-Hearing Association (CCC-A) or are Fellows of the American Academy of Audiology (F-AAA).

Treatment for Hearing Loss

Hearing aids are the primary nonmedical treatment for hearing loss. The most common type of hearing loss involves outer hair cell dysfunction; hearing aids allow an amplification of sound to overcome this problem. A hearing aid's basic components are the microphone, amplifier, and receiver. A number of circuit options modify how the hearing aid makes certain sounds louder.

There are several hearing aid styles; some are worn on the body while others fit behind the ear or in the ear. Some specialized hearing aids are attached to the bone of the skull to send sound waves directly to the cochlea and may be used in conditions of conductive hearing loss not amenable to standard hearing aids. No single style or manufacturer is best — hearing aid selection is based on a child's individual needs. Most kids with bilateral hearing loss (both ears) wear two hearing aids.