The newborn hearing test takes about 5 minutes, runs while the baby is asleep, and is one of the most useful screens of early childhood. It is offered to every baby in the UK, usually before they leave the maternity unit, and the result is given there and then.
Understanding what the test is doing — and what a 'refer' actually means versus what parents often fear it means — keeps the experience proportionate to the reality.
Healthbooq keeps a record of newborn screening results alongside vaccinations and developmental milestones.
How the Test Works
The standard first-line test is AOAE (automated otoacoustic emissions). A small soft-tipped probe is placed in the ear canal. The probe plays a series of soft clicks and listens for the cochlea's echo — tiny sounds that a healthy inner ear produces in response to stimulation.
If the echoes are detected at the expected level in both ears, the result is clear (pass). If they are not, the result is refer.
Each ear takes a minute or two. The baby just needs to be reasonably quiet — feeding or sleeping is ideal. Background noise (a busy ward, a chatty visitor, an air conditioner) makes the test harder.
For babies who have spent over 48 hours in NICU, the first-line test is AABR (automated auditory brainstem response) instead, because NICU babies are at higher risk of auditory neuropathy — a pattern where the cochlea works but the auditory nerve doesn't transmit signals properly. AOAE alone misses it; AABR catches it. AABR uses three small surface electrodes (forehead, shoulder, behind one ear) to record the brain's electrical response to sound through small earphones.
Both tests are non-invasive and painless. Both can be done while the baby sleeps.
Why Babies Get a 'Refer'
About 1 in 30 well term babies refer on the first AOAE round. The vast majority are not hearing impaired. The common reasons:
- Vernix or amniotic fluid in the ear canal — the canal hasn't fully cleared yet. Usually resolves within a few days.
- Middle ear fluid — common in the first days, especially after caesarean delivery.
- The baby was crying, moving, or feeding during the test.
- Background noise in the room.
- Probe positioning — needs a good seal in the canal.
If AOAE refers in one or both ears, a second AOAE attempt is usually made on the same day or within 1–2 weeks. If that also refers, the baby moves to AABR. If AABR also refers, the baby is referred for a full diagnostic audiological assessment, ideally completed by 4 weeks of age.
What the Diagnostic Assessment Looks Like
Done at the local audiology department, the diagnostic assessment uses several tools to build a complete picture:
- ABR (auditory brainstem response) — like AABR but tested across multiple frequencies and intensities, giving a hearing threshold for each ear in decibels
- Tympanometry — measures middle ear function, distinguishes conductive (middle ear) from sensorineural (inner ear/nerve) loss
- OAE testing — confirms cochlear function
- In older infants, visual reinforcement audiometry — looking-towards-sound responses
The whole assessment usually takes 1–2 visits over a couple of hours.
If Permanent Hearing Loss Is Confirmed
About 1–2 in every 1,000 babies have permanent bilateral hearing loss. If diagnosis is confirmed, a multidisciplinary team begins working with the family within days:
- Paediatric audiologist — fits hearing aids, monitors hearing
- Teacher of the deaf — supports communication and language development
- Speech and language therapist — early intervention from infancy
- Paediatrician — investigates cause (genetic testing, CMV PCR if within first 21 days, kidney imaging if syndromic features)
- Ophthalmologist — for some causes that affect both vision and hearing
Hearing aids can be fitted from about 4 weeks of age. For severe-to-profound sensorineural loss with limited benefit from hearing aids, cochlear implant assessment usually begins around 6 months, with implantation typically at 9–12 months.
The 1-3-6 international standard:
- By 1 month — screened
- By 3 months — diagnosed
- By 6 months — early intervention started
Children meeting this timeline typically achieve language outcomes close to their hearing peers, especially with cochlear implants for profound loss. Children identified late (after 18 months) lag behind significantly and often catch up only partially.
Causes Worth Knowing
About half of congenital hearing loss is genetic — most commonly mutations in the GJB2 gene affecting connexin 26 (a protein essential for cochlear function), usually inherited recessively. Family history is asked about, and genetic testing is offered.
The most common non-genetic cause is congenital cytomegalovirus (cCMV). CMV is a common virus most adults have had; if caught for the first time in pregnancy, it can cross the placenta. Most cCMV-affected babies are asymptomatic at birth, but cCMV can cause progressive hearing loss across the first months and years. If CMV is found in a hearing-loss workup within the first 21 days of life, antiviral treatment with valganciclovir can reduce the risk of further loss.
Other causes: severe prematurity, severe jaundice needing exchange transfusion, bacterial meningitis (postnatal), and rare intrauterine infections.
What If the Screen Was Clear?
A clear screen is good news but not a guarantee for life. Around half of childhood hearing loss is acquired or progressive — it develops after the newborn screen. Reasons to keep watching:
- Glue ear — fluid behind the eardrum, peaks at 2–5 years, common after colds, causes fluctuating conductive loss. Most resolves spontaneously; some need grommets.
- Acquired sensorineural loss — from meningitis, chemotherapy, head trauma
- Progressive genetic loss — present from birth but only audiometrically detectable later
- Late-onset cCMV-related loss
Listening for these in your child:
- Newborn: startles to loud sounds, quietens to familiar voice
- 3–4 months: turns toward sounds, recognises parents' voices
- 6 months: babbles using a range of sounds, responds to their name
- 9 months: turns to sounds in another room, distinguishes parents from strangers by voice
- 12 months: responds to simple instructions, says a couple of words
- 18 months: 6+ clear words, follows simple commands
- 2 years: 50+ words, two-word combinations, follows two-step instructions
Concerns at any stage are worth raising with the GP or health visitor. Most are glue ear; some are not.
Key Takeaways
All UK babies are offered a hearing screen, usually before they leave the maternity unit. Most well term babies have AOAE — a soft probe in the ear that listens for a tiny echo from the cochlea. NICU babies start with AABR — small electrodes that measure the brain's response to sound. A 'refer' result is not a hearing loss diagnosis: about 1 in 30 babies refer the first time, and most are fine on retest. Around 1–2 per 1,000 babies have permanent hearing loss; finding it before 3 months of age and starting hearing aids by 6 months keeps language development on track.
