Types of Hearing Tests
In 1999, the American Academy of Pediatrics (AAP) issued a statement recommending that hearing screening tests be implemented nationwide. According to the NIH, 39 states plus the District of Columbia currently mandate newborn hearing screening tests be performed by hospital technicians prior to discharge, and an additional five states have voluntary programs. These tests are made available to parents and documented in the infant's medical record by the specialist who performed the exam. If an infant should fail, a repeat test is usually done prior to discharge.
Two types of hearing screening tests are performed on infants:
- Otoacoustic Emissions (OAE): Otoacoustic emissions are sounds made by the cochlea, the fluid-filled part of the inner ear that converts sounds/vibrations into electrical signals that are then sent to the brain. The OAE requires the placement of a tiny earphone/probe into a newborn's ear canal. Sounds are played, and the baby's responses are measured. If an infant suffers from hearing loss, no echo will be detected.
- Auditory Brainstem Response (ABR): The ABR test consists of small electrodes attached to the newborn's head. Soft clicking sounds are presented into the ear through small earphones. These sounds cause brainwaves, which are picked up through the electrodes and recorded by a computer.
OAE and ABR can be used separately or in combination. Each is done while the newborn is asleep, and there are no risks involved. Some hospitals prefer to perform the OAE test first, and if an infant fails, the ABR is used to follow up.
When a Test Is Failed
A failed first test does not automatically mean that a newborn has a hearing loss. "There are several reasons why your baby may have failed: vernix, or fluid, may be present in the ear canal, which can interfere with the test," explains Dr. Jay Dolitsky, MD, director of pediatric otolaryngology at the New York Eye and Ear Infirmary in Manhattan. Other factors for failure include movement, fussiness, and/or crying during the screening.
"Babies who fail in the hospital are screened again in about four weeks. If they fail during this prescreening, they should be scheduled for full diagnostic evaluation," states Dr. Spivak.