Objective hearing tests: otoacoustic emissions and ABR
- Examination
Otoacoustic emissions and the auditory brainstem response test hearing without the patient answering, so they work in newborns and sleeping children.
What it is
Objective hearing tests need no response from the patient. Otoacoustic emissions (OAE) are faint sounds produced by the outer hair cells of a healthy cochlea and picked up by a microphone in the ear canal. The auditory brainstem response (ABR) records, with surface electrodes on the head, the electrical activity of the auditory nerve and brainstem pathways after a click or tone. OAE check the cochlea; ABR checks the whole pathway up to the brainstem. Both are used to screen newborns, to estimate hearing in children who cannot do audiometry and, for ABR, to look for retrocochlear problems.
Findings and interpretation
- OAE pass: the outer hair cells and middle ear work; a neural problem is still possible.
- OAE absent: cochlear hearing loss, or simply fluid, wax or a blocked probe; repeat the test or go to ABR.
- Raised ABR thresholds with absent OAE fit a cochlear or conductive loss; check the middle ear.
- Auditory neuropathy: OAE present, ABR absent or very abnormal; speech understanding is worse than the audiogram predicts.
- In adults, ABR helps identify retrocochlear causes; gadolinium-enhanced MRI is the imaging test for a vestibular schwannoma.
- OAE are also used to monitor people receiving ototoxic drugs.
How it is done
- Check the canal and middle ear first: wax or middle-ear fluid can block emissions and cause a failed screen.
- OAE: a soft probe in the canal plays clicks or tone pairs and its microphone records the cochlear echo; it takes a few minutes.
- ABR: electrodes on the head record brain waves to sound while the baby sleeps naturally.
- Screening ABR is automated and gives pass or refer; diagnostic ABR estimates the hearing threshold of each ear.
- Babies with risk factors (intensive care, prematurity, hypoxia, jaundice) need ABR screening: OAE alone miss auditory neuropathy.
- After a refer result, arrange a full audiological evaluation (diagnostic ABR, tympanometry, ear exam) before 3 months of age.
Reading OAE and ABR together
| OAE | ABR | Interpretation |
|---|---|---|
| Present | Normal | Normal pathway up to the brainstem |
| Absent | Raised threshold | Cochlear or conductive hearing loss: examine the middle ear |
| Present | Absent or very abnormal | Auditory neuropathy spectrum disorder |
| Present or absent | Abnormal on one side only | Possible retrocochlear lesion: MRI |
Common mistakes
- Treating a screening refer as certain deafness, or dismissing it as a machine error: both delay diagnosis.
- Screening intensive care babies with OAE only and missing auditory neuropathy.
- Thinking a pass at birth protects for life: meningitis, chronic otitis media and ototoxic drugs cause later loss, so test again if parents or teachers notice a problem.
Next step / Initial management
- Failed screen: repeat screening, then a full audiological evaluation before 3 months of age.
- Confirmed permanent loss: refer to ENT and audiology for hearing aids or a cochlear implant, and enrol in early intervention before 6 months.
- Suspected auditory neuropathy: refer to a specialised audiology and ENT centre; hearing aids help some children and cochlear implants help others.
- Adult with asymmetric loss and an abnormal ABR: priority ENT referral for MRI.
Test yourself
Think of the answer, then tap the question to see it.
A baby discharged from intensive care passes OAE but has an absent ABR. What is the likely diagnosis?
Auditory neuropathy spectrum disorder: the outer hair cells work but the neural signal is abnormal.
What are the 1-3-6 benchmarks of newborn hearing programmes?
Screen by 1 month, complete the diagnosis by 3 months and start early intervention by 6 months.
Which cells generate otoacoustic emissions?
The outer hair cells of the cochlea (a normal middle ear is also needed to record them).
Connections
Educational content; it does not replace a medical assessment and is not a clinical instruction. For a real case, follow current guidelines and specialist advice.
Sources: Screening for Hearing Loss (Hearing Loss in Children) (Centers for Disease Control and Prevention, 2024); Auditory Neuropathy (NIDCD, National Institutes of Health, 2018); Hearing Loss (MSD Manual Professional Edition, 2026); Deafness and hearing loss (fact sheet) (World Health Organization, 2026).
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Representative model, for educational purposes only.