Newborn Hearing Test: OAE Screening for Early Detection

What Is the OAE Newborn Hearing Test?

The OAE (Otoacoustic Emissions) test is a quick, painless hearing screening that measures sounds produced by the inner ear in response to audio stimulation. A small probe placed in the baby's ear plays soft clicks and records the echo from healthy hair cells in the cochlea, providing immediate results about hearing function.

The OAE test is the most common method used for universal newborn hearing screening worldwide. OAE stands for Otoacoustic Emissions, which are tiny sounds produced by the inner ear when healthy hair cells in the cochlea respond to sound stimulation. These emissions were first discovered by British physicist David Kemp in 1978 and have since revolutionized how we screen for hearing loss in newborns.

When sound enters a healthy ear, it travels through the ear canal, causes the eardrum to vibrate, and moves through the middle ear bones to reach the cochlea in the inner ear. The cochlea contains thousands of tiny hair cells that convert sound vibrations into electrical signals sent to the brain. In a remarkable phenomenon, these hair cells also produce their own faint sounds in response to stimulation - these are the otoacoustic emissions that the test measures.

The presence of otoacoustic emissions indicates that the outer hair cells in the cochlea are functioning normally, which is essential for normal hearing sensitivity. If these emissions are absent or significantly reduced, it may indicate a problem with the outer or middle ear, or damage to the cochlear hair cells.

Types of OAE Tests

There are two main types of OAE tests used in clinical practice. Transient Evoked Otoacoustic Emissions (TEOAEs) use brief click sounds and measure the response across a broad frequency range. Distortion Product Otoacoustic Emissions (DPOAEs) use two simultaneous tones and can provide frequency-specific information about cochlear function. Both types are effective for newborn screening, though TEOAEs are more commonly used in hospital settings due to their speed and simplicity.

Why OAE Testing Is Preferred for Newborns

OAE testing has become the gold standard for initial newborn hearing screening for several important reasons. The test is objective, meaning it does not require any behavioral response from the baby, which is crucial since newborns cannot indicate whether they hear sounds. It is also fast, typically taking only 5-10 minutes per ear, and can be performed while the baby is sleeping or resting quietly. The equipment is portable, allowing testing to be done at the bedside, and the results are available immediately.

Why Is Early Hearing Screening Important?

Early hearing screening is critical because the first three years of life represent a crucial window for brain development and language acquisition. Children whose hearing loss is identified by 3 months and who receive intervention by 6 months show language development comparable to their hearing peers, while later identification leads to significant delays.

Hearing is not just about perceiving sound - it is fundamental to how infants develop speech, language, and cognitive abilities. From the moment of birth, babies begin learning language by listening to the sounds around them. They learn the rhythm and melody of their native language, begin to associate sounds with meanings, and eventually start producing their own words. This process depends entirely on being able to hear clearly.

Research spanning several decades has consistently demonstrated the profound impact of early identification and intervention. The landmark Early Hearing Detection and Intervention (EHDI) studies showed that children whose hearing loss was identified before 6 months of age achieved language scores within the normal range by age 5, while children identified after 6 months showed persistent language delays. This finding has been replicated across numerous studies and different populations worldwide.

The reason for this dramatic difference lies in brain plasticity - the brain's ability to form new neural connections. During the first few years of life, the auditory cortex is highly plastic and primed to develop in response to sound input. If sound input is absent or distorted due to hearing loss, the brain's auditory areas may be repurposed for other functions, making it much harder to develop listening and spoken language skills later, even with hearing aids or cochlear implants.

The 1-3-6 Goals

International guidelines, including those from the Joint Committee on Infant Hearing (JCIH) and the World Health Organization, recommend the "1-3-6" approach to newborn hearing:

• 1 month: All infants should be screened for hearing loss by 1 month of age (ideally before hospital discharge)
• 3 months: Infants who do not pass screening should receive comprehensive audiological evaluation by 3 months of age
• 6 months: Infants confirmed with hearing loss should begin early intervention services by 6 months of age

Meeting these benchmarks gives children the best possible chance for normal language development. Some programs are now advocating for even earlier goals - the "1-2-3" approach - to maximize the benefits of early intervention.

Prevalence of Congenital Hearing Loss

Congenital hearing loss is one of the most common conditions present at birth. Approximately 1-3 babies per 1,000 are born with significant permanent hearing loss in their better-hearing ear. In neonatal intensive care units (NICUs), where babies may have additional risk factors, the rate is even higher - approximately 2-4 per 100 babies.

Before universal newborn hearing screening programs were implemented, the average age of identification for hearing loss was 2-3 years - well past the critical window for optimal language development. Today, with screening in place in most developed countries, most children with hearing loss are identified within the first few weeks of life.

When and Where Is the Hearing Test Performed?

Newborn hearing screening is typically performed in the hospital or birthing center before discharge, usually within 24-48 hours after birth. If your baby is born at home or in a facility without screening equipment, a test should be arranged within the first few weeks of life through your pediatrician or a hearing screening program.

The timing of the newborn hearing test has been carefully considered to balance several factors. Testing too early - within the first 24 hours - may result in higher rates of false referrals because amniotic fluid and vernix (the protective waxy coating on newborn skin) may still be present in the ear canals. Testing too late means the critical window for early intervention may be unnecessarily shortened if hearing loss is present.

Most hospitals and birthing centers perform the screening test between 24 and 48 hours after birth, which typically aligns with routine newborn examinations and allows adequate time for the ear canals to clear. The test is usually conducted in the nursery or in the mother's room, wherever the baby can be kept calm and quiet.

Hospital Screening Process

In hospital settings, trained staff members - often nurses, audiologists, or hearing screening technicians - perform the tests using portable OAE equipment. The entire process typically takes only 5-10 minutes per ear when the baby is sleeping or resting quietly. Many hospitals have implemented protocols to ensure that all babies are screened before discharge, with results documented in the medical record and communicated to parents.

If your hospital stay is brief, as is common after uncomplicated vaginal deliveries, the screening may be performed on the day of discharge. Some hospitals arrange outpatient follow-up screening for babies who are discharged before testing can be completed or whose results require verification.

What If Your Baby Is in the NICU?

Babies who require care in a neonatal intensive care unit (NICU) have a higher prevalence of hearing loss due to various risk factors, including prematurity, certain medications, infections, and hyperbilirubinemia (jaundice). For this reason, NICU babies often receive more comprehensive hearing testing.

Many NICU programs use Auditory Brainstem Response (ABR) testing rather than or in addition to OAE testing. ABR provides information about the entire hearing pathway, including the auditory nerve and brainstem, which can be affected in some NICU babies even when the cochlea is functioning normally. Your baby's medical team will determine the appropriate testing protocol based on their specific risk factors.

Home Births and Outpatient Screening

If your baby is born at home or in a facility without hearing screening capabilities, it is essential to arrange for screening as soon as possible. Contact your pediatrician or family doctor within the first few days after birth to schedule a hearing test. Many communities have outpatient screening programs at hospitals, audiology clinics, or public health departments.

How Should Parents Prepare for the Test?

The best preparation for the OAE hearing test is to ensure your baby is calm and ideally sleeping. Feeding your baby shortly before the test can help achieve this state. The test requires no special preparation, and parents do not need to bring any special equipment or materials.

One of the many advantages of OAE testing is its simplicity - there is no complex preparation required. However, there are a few things parents can do to help ensure the test goes smoothly and produces accurate results.

Timing the Test Around Feeding

The OAE test is most successful when the baby is asleep or resting quietly. Any movement, crying, or fussiness can introduce noise that interferes with the sensitive measurements. For this reason, many screening programs recommend feeding your baby shortly before the scheduled test time. A full, content baby is much more likely to stay calm or drift off to sleep during the brief procedure.

If you are breastfeeding, try to time a feeding session about 30 minutes before the test. If you are formula feeding or using expressed breast milk, the same timing applies. The goal is for your baby to be satisfied and drowsy when the test begins.

What Parents Should Know

Understanding what to expect can help parents feel more comfortable during the screening process. Here are some key points to keep in mind:

• You can usually stay with your baby: Most screening programs encourage parents to be present during the test. Your presence can help keep your baby calm.
• The test is completely safe: There is no radiation, no needles, and no discomfort involved. The sounds used are very soft and will not harm your baby's hearing.
• Results are immediate: You will typically know whether your baby passed the screening before you leave the testing area.
• One test may not be enough: If the initial test is inconclusive, a retest will be scheduled. This is common and not cause for alarm.

Questions to Ask Your Healthcare Provider

Before the screening test, consider asking your healthcare provider the following questions:

• When will the hearing test be performed?
• What type of test will be used (OAE or ABR)?
• How will I receive the results?
• What happens if my baby needs a retest?
• Are there any risk factors in my baby's history that warrant additional testing?

How Does the OAE Hearing Test Work?

During the OAE test, a small probe containing a speaker and microphone is gently placed in your baby's ear canal. The speaker plays soft clicking sounds, and the microphone records the echoes produced by healthy hair cells in the cochlea. A computer analyzes these emissions and determines whether the response is within normal range.

The OAE testing procedure is elegantly simple yet remarkably sophisticated in what it measures. Understanding how the test works can help parents appreciate what a "pass" or "refer" result actually means.

Step-by-Step Process

The screening technician or audiologist begins by selecting an appropriately sized probe tip - these come in various sizes to fit newborn ear canals comfortably. The probe is then gently inserted into the baby's ear canal, creating a seal that is necessary for accurate measurements. This insertion is no more invasive than placing a small earplug.

Once the probe is properly positioned, the equipment delivers a series of very soft clicking sounds through the tiny speaker in the probe. These sounds travel down the ear canal, through the middle ear, and into the cochlea. In a healthy cochlea, the outer hair cells respond to these sounds by contracting and relaxing, which produces their own faint sounds - the otoacoustic emissions.

The microphone in the probe is sensitive enough to detect these incredibly quiet emissions, which are sent to a computer for analysis. The computer determines whether the emissions are present and strong enough to indicate normal cochlear function. This entire process typically takes only a few minutes per ear.

What the Test Measures

The OAE test specifically measures the function of the outer hair cells in the cochlea. These specialized cells are responsible for amplifying soft sounds and are often the first to be damaged by noise exposure, certain medications, or genetic factors. When outer hair cells are functioning properly, they produce robust otoacoustic emissions in response to sound stimulation.

It is important to understand that the OAE test assesses only part of the hearing system. It does not evaluate the auditory nerve, the brainstem auditory pathways, or the brain's ability to process sound. This is why some babies who pass OAE screening may still have a type of hearing loss called auditory neuropathy spectrum disorder, where the cochlea works normally but the auditory nerve does not transmit signals properly.

Factors That Can Affect Test Results

Several factors can cause an OAE test to produce inconclusive or "refer" results even when the baby's hearing is actually normal:

• Fluid in the ear canal: Amniotic fluid or vernix remaining in the ear canal can block sound transmission and prevent accurate measurement.
• Middle ear fluid: Some newborns have temporary fluid in the middle ear that clears within days to weeks.
• Baby movement or crying: Any noise from the baby can overwhelm the very quiet emissions being measured.
• Environmental noise: Loud background noise in the testing environment can interfere with measurements.
• Collapsed ear canals: Newborn ear canals are very soft and can sometimes collapse when the probe is inserted, blocking sound transmission.

What Do the Hearing Test Results Mean?

OAE screening results are reported as "pass" or "refer" (sometimes called "did not pass"). A pass result indicates normal cochlear function in the tested ear. A refer result means the test was inconclusive and additional testing is needed - it does not necessarily indicate hearing loss, as many babies who receive refer results have normal hearing on follow-up testing.

Understanding your baby's hearing screening results is important for knowing what steps, if any, need to be taken next. The terminology used can sometimes be confusing, so let us clarify what each result means.

Pass Result

A "pass" result indicates that otoacoustic emissions were detected at appropriate levels in the tested ear. This suggests that the outer hair cells in the cochlea are functioning normally, which is necessary for normal hearing sensitivity. A pass result in both ears is reassuring and typically means no further hearing testing is needed at that time.

However, it is important to understand that a pass result does not guarantee perfect hearing forever. Hearing loss can develop later in childhood due to infections, medications, genetic factors, or noise exposure. Parents should continue to monitor their child's hearing and speech development and report any concerns to their healthcare provider.

Refer Result

A "refer" result (also called "did not pass" in some programs) means that the test did not detect adequate otoacoustic emissions. This result indicates the need for further evaluation but does not diagnose hearing loss. In fact, most babies who receive a refer result on initial screening have normal hearing when retested.

There are several reasons why a baby might receive a refer result despite having normal hearing:

• Residual fluid or debris in the ear canal from birth
• Temporary middle ear fluid
• Baby was too active or noisy during testing
• Poor probe fit or environmental noise interference

If your baby receives a refer result, try not to panic. The screening program will schedule a retest, typically within a few weeks. The retest rate varies by program but is generally between 2-10% of all babies screened.

Next Steps After a Refer Result

If your baby's initial screening results in a refer, the following steps are typically recommended:

• Outpatient retest: A repeat OAE test is usually scheduled within 1-2 weeks to allow time for any temporary conditions (like fluid in the ear) to resolve.
• Diagnostic evaluation: If the retest also results in a refer, your baby will be referred for comprehensive audiological evaluation, typically including diagnostic ABR testing.
• Medical evaluation: If hearing loss is confirmed, your baby may be referred to an ear, nose, and throat (ENT) specialist to evaluate for treatable causes.

What Happens If My Baby Needs Further Testing?

If OAE screening results are inconclusive after retesting, your baby will be referred for comprehensive audiological evaluation, typically including Auditory Brainstem Response (ABR) testing. ABR measures electrical activity in the hearing pathway and can determine the type and degree of hearing loss if present. The goal is to complete diagnostic evaluation by 3 months of age.

When a baby does not pass OAE screening on repeated attempts, the next step is diagnostic hearing evaluation. This is a more comprehensive assessment performed by a pediatric audiologist - a healthcare professional specializing in hearing assessment and rehabilitation in children.

Auditory Brainstem Response (ABR) Testing

ABR testing is considered the gold standard for diagnosing hearing loss in infants. Unlike OAE testing, which only evaluates cochlear function, ABR assesses the entire auditory pathway from the ear to the brainstem. During the test, small electrodes are placed on your baby's head to measure electrical activity generated by the auditory nerve and brainstem in response to sounds played through earphones or insert probes.

ABR testing is typically performed while the baby is sleeping naturally or, in some cases, under light sedation. The test takes longer than OAE screening - usually 1-2 hours - but provides much more detailed information about hearing thresholds across different frequencies.

What ABR Results Can Tell Us

Diagnostic ABR testing can determine:

• Whether hearing loss is present: The test can confirm or rule out hearing loss that was suspected from screening results.
• The degree of hearing loss: Results indicate whether hearing loss is mild, moderate, severe, or profound.
• The type of hearing loss: Testing can help distinguish between conductive hearing loss (problems with the outer or middle ear) and sensorineural hearing loss (problems with the inner ear or auditory nerve).
• Frequency-specific information: Results show which frequencies (pitches) are affected, which is important for hearing aid fitting if needed.

Additional Evaluations

If hearing loss is confirmed, your baby's healthcare team may recommend additional evaluations to determine the cause and best treatment approach:

• Medical evaluation: An ENT physician will examine your baby's ears and may order imaging studies (CT scan or MRI) to look for structural abnormalities.
• Genetic testing: Approximately 50-60% of congenital hearing loss has a genetic cause. Genetic testing can provide information about the cause and prognosis.
• CMV testing: Congenital cytomegalovirus (CMV) infection is a leading non-genetic cause of hearing loss. Testing may be recommended, especially for babies with progressive or fluctuating hearing loss.
• Ophthalmology evaluation: Some genetic syndromes associated with hearing loss also affect vision, so an eye examination may be recommended.

Early Intervention Services

If your baby is diagnosed with hearing loss, early intervention services should begin as soon as possible - ideally by 6 months of age. Early intervention programs provide a range of services to support your baby's communication development and help your family learn strategies for fostering language acquisition.

Services may include:

• Hearing aid fitting and management
• Evaluation for cochlear implant candidacy (for severe to profound hearing loss)
• Speech-language therapy
• Parent education and support
• Communication options counseling (spoken language, sign language, or combined approaches)

What Is the Difference Between OAE and ABR Tests?

OAE tests measure sounds produced by the inner ear's hair cells, while ABR tests measure electrical activity in the auditory nerve and brainstem. OAE is faster and used for initial screening, while ABR provides more comprehensive diagnostic information about the entire hearing pathway. Some babies may need both tests for complete evaluation.

Parents often hear about both OAE and ABR testing and wonder what the differences are. Understanding these two tests can help you better understand your baby's hearing evaluation process.

When Each Test Is Used

OAE testing is ideal for initial newborn hearing screening because it is fast, portable, and requires minimal equipment. It effectively identifies babies who may have cochlear dysfunction and need further evaluation. However, OAE cannot detect auditory neuropathy spectrum disorder, where the cochlea functions normally but the auditory nerve does not transmit signals properly.

ABR testing is used when more detailed information is needed - either to confirm hearing loss suspected from OAE screening or to determine the degree and type of hearing loss for treatment planning. ABR is also the preferred screening method for NICU babies who have higher rates of auditory neuropathy.

Combined Protocols

Some hearing screening programs use a two-stage approach, starting with OAE and following up with ABR if needed. Others, particularly in NICUs, may use ABR as the primary screening tool. The specific protocol depends on the resources available and the population being screened.

Frequently Asked Questions