Almost every baby born in an American hospital is screened for hearing before going home, usually while asleep and without the parents noticing much. The urgency behind that routine is developmental.
Two automated tests do the screening
One method measures otoacoustic emissions, faint sounds the inner ear produces in response to a click. A probe delivers the sound and records whether the response is present.
The other records auditory brainstem response, using surface electrodes to detect the nervous system's electrical response to sound presented through small earphones.
Both are automated, produce a pass or refer result, and require no response from the infant. Which is used depends on the hospital and sometimes on the baby's risk factors.
A refer result is not a diagnosis
Screening is calibrated to be sensitive, so it flags more infants than have hearing loss. Fluid or debris in the ear canal after birth is a frequent cause of a refer result.
The next step is a repeat screen or a full diagnostic audiological evaluation, which is a different and more detailed procedure performed by an audiologist.
Parents are given follow-up instructions at discharge. Those appointments are the point at which anything is actually determined.
The timeline exists because of language windows
Spoken language development depends on auditory input during early life, and delays in identifying hearing loss translate into delays in language exposure.
National early hearing detection programs are built around screening, diagnosis and intervention each occurring within defined early timeframes for this reason.
The benefit of early identification is access to intervention, whether that is amplification, visual language or another approach chosen with the family.
Programs are run at state level
Screening is coordinated through state early hearing detection and intervention programs, which track results and follow up on infants who do not complete the next step.
Requirements, reporting and the follow-up system differ by state. Some states mandate screening; others achieve near-universal coverage through hospital practice.
Loss to follow-up is the recognized weak point. A family that moves, changes providers or misses the appointment can drop out of the sequence.
Passing the newborn screen is not permanent
Some hearing loss is progressive or acquired later, from illness, injury or genetic causes that emerge after the newborn period.
Pediatric well-child visits include ongoing surveillance, and parent concern about a child's response to sound or speech development is a recognized reason to reassess.
Any concern about an individual child's hearing belongs with a pediatrician or an audiologist rather than with the newborn result alone.