The Newborn Hearing Screening (NHS) is a quick, non-invasive procedure designed to identify hearing loss in infants shortly after birth. This screening is a standard practice in hospitals and birthing centers and serves as the first step in the Early Hearing Detection and Intervention (EHDI) program. The goal of the NHS is to ensure that any potential hearing issues are detected early, which is paramount for a child’s speech and language development. Screening is performed before the baby leaves the hospital, or by one month of age at the latest.
Understanding the Screening Methods
The screening is performed using one of two methods, or sometimes both, to assess different parts of the auditory system. The Otoacoustic Emissions (OAE) test measures the function of the inner ear’s outer hair cells. A small probe placed in the ear canal emits a soft sound and measures the faint echo produced by a healthy inner ear.
The OAE test is sensitive to blockages in the outer or middle ear, such as fluid or residual vernix, which prevent the echo from being measured. The Automated Auditory Brainstem Response (AABR) test assesses how sound travels from the ear to the brainstem. For the AABR, small electrodes are placed on the baby’s head and neck to record electrical activity in the auditory nerve and brainstem in response to clicking sounds.
The AABR test measures a neural response deeper within the auditory pathway, making it less susceptible to outer or middle ear issues than the OAE test. Both screenings work best when the infant is resting quietly or asleep, as movement or crying can interfere with the recording. These methods are designed as screening tools, quickly indicating whether further testing is necessary.
Decoding the Results: Pass Versus Refer
The result of a newborn hearing screening will be either a “Pass” or a “Refer” for each ear. A “Pass” result indicates the baby’s hearing is likely within normal limits for the range of sounds tested. Most newborns who pass this initial screen have healthy hearing, and no further testing is required.
A “Refer” result, sometimes labeled “Fail,” does not mean the baby has permanent hearing loss, but indicates that further testing is needed. This outcome means the screening equipment did not record a clear response from the auditory system in that ear. Approximately 90% of newborns who initially receive a “Refer” result go on to pass subsequent testing.
Several common reasons for a “Refer” result are not related to permanent hearing impairment. The most frequent cause is the presence of fluid in the middle ear or vernix in the ear canal, which blocks the sound or the emission. Temporary factors, such as the baby being restless, crying during the test, or noise in the testing room, can also cause a “Refer.” The “Refer” serves as a flag that a more definitive evaluation is necessary.
Essential Follow-Up Steps After a Referral
A “Refer” result necessitates prompt follow-up, which begins with a repeat screening. This rescreening is often scheduled before the baby is one month old to allow time for residual fluid or vernix to clear naturally. If the baby still receives a “Refer” on the second screening, parents are referred to a pediatric audiologist for a comprehensive diagnostic evaluation.
This comprehensive evaluation must be completed by three months of age to ensure timely intervention if hearing loss is confirmed. The diagnostic test is usually a full Auditory Brainstem Response (ABR) evaluation, which provides detailed information about the extent and type of hearing loss. The audiologist uses this information to confirm or rule out a hearing loss, unlike the initial screening which only indicates the need for further testing.
Diagnosis is important because intervention, such as hearing aids, should begin by six months of age to maximize language development outcomes. This structured timeline ensures a child with hearing loss receives support during the critical period for speech and language acquisition.