Is your baby calmed by the sound of your voice? Does your baby get startled when he or she hears a loud noise? If you’ve answered no to either of these questions, your baby might have hearing loss.
Hearing loss (or hearing impairment) is defined as hearing problems in one or both ears. It includes the inability to hear the range of sounds that is normal for most people. People with hearing loss or hearing impairment might hear some sounds, but they also might hear no sounds.
Hearing loss is the most common developmental abnormality found at birth. Data show that 3 in every 1000 babies are born with hearing loss each year in the United States.1
Because your baby’s speech and overall communication depends on his or her ability to hear, it’s important to have your newborn’s hearing tested before he or she leaves the hospital. If your baby’s hearing was not screened before leaving the hospital, it’s best to have him or her screened within the first 3 weeks of life to address hearing problems and help prevent difficulties with speech and listening.
Hearing tests for infants are not expensive. In most cases, insurance covers the cost of screening. In addition, screening does not hurt the baby. A preliminary hearing test lasts just long enough (4 to 7 minutes) for an audiologist to play soft clicking noises into your baby’s ear.
If your baby shows signs of hearing loss, your audiologist will use additional tests to identify the extent of the loss. A variety of tests can be used to provide specifics about hearing loss that will help the audiologist decide what treatment would be best for your child.
Otoacoustic Emissions Screening
In addition to receiving sound, a healthy inner ear (cochlea) produces low-intensity sounds called otoacoustic emissions (OAEs). Babies with a certain sensorineural hearing loss level have no OAEs—a condition known as auditory neuropathy/dys-synchrony. During OAE testing, the audiologist uses soft clicking sounds to compare normal OAE results with normal auditory brain response (ABR) results. Fluid and negative ear pressure in the middle ear from ear infections can interfere with OAE testing. To ensure accurate results, your baby’s middle ear must be completely clear for OAE testing.
Auditory Brain Response Testing
Clicking sounds, tone bursts, and a bone conduction test can be used to measure your baby’s auditory brainstem response (ABR). ABR tests allow the audiologist to accurately determine your baby’s ear function, cranial nerve function, and other brain functions associated with hearing. They allow audiologists to determine the degree and type of hearing loss so that your baby can be fitted for a hearing aid. ABR testing is typically performed without sedation in babies younger than 6 months of age. If your baby is age 6 months or older and needs ABR testing, ask your audiologist about sedation. He or she will explain what is involved and help guide you about what would work best for your baby.
If your baby does not pass both the OAE and ABR tests, he or she will be tested further to determine the extent of his or her hearing loss. In addition, the audiologist will ask for information to help identify other conditions that might indicate an increased risk for hearing loss, including:
- Family history of hearing loss
- Problems during pregnancy, including illnesses and medications
- Complications during labor and delivery
- How long your baby was in the neonatal intensive care unit (NICU)
Tympanometry assesses the condition of the middle ear, mobility of the eardrum (tympanic membrane), and how well the middle-ear bones conduct sound. Because ear canals in babies age 6 months and younger are soft and small, tympanometry can be inaccurate. In cases such as these, special equipment that generates a high frequency can be used to increase the reliability of the test results.
Behavioral audiometry is used to test for the lowest volume a child can hear at different frequencies. Because behavioral audiometry requires feedback from the listener, the test works best in children who can tell the audiologist what he or she is hearing.
Visual Reinforcement Audiometry
Visual reinforcement audiometry (VRA) often is used in addition to other hearing tests in babies age 6 to 36 months to ensure accurate results. During VRA, your baby will sit on your lap in a soundproof booth. He or she will be trained to turn toward a toy that lights up and moves when he or she hears a sound.
Conditioned Play Audiometry
Children age 2 years of age and older can be trained for conditioned play audiometry (CPA). During CPA, the audiologist will teach your toddler to drop a ball in a bucket or perform another enjoyable activity when he or she hears a tone.
Although hearing screening for newborns is designed to identify infants who have congenital hearing loss, some babies have mild hearing loss that cannot be detected initially. In some cases, their hearing loss will become more severe (progressive) as they mature. Other children experience permanent hearing loss after birth (delayed-onset). Babies who are at risk for progressive or delayed-onset hearing loss are candidates for audiologic monitoring.
Vohr B. Overview: Infants and children with hearing loss, Part I. Ment Retard Dev Disabil Res Rev. 2003;9:62-64.