BERA, ABR, auditory brainstem response
Brainstem Evoked Response Audiometry
An objective test of the hearing nerve and brainstem pathway. Small surface electrodes record the brain's automatic response to sound while the patient rests or sleeps quietly.
What this assessment is
Brainstem evoked response audiometry records the tiny electrical activity generated by the auditory nerve and brainstem in the first ten milliseconds after a sound. Click or tone burst stimuli are delivered through insert earphones and thousands of responses are averaged by the equipment until a clear waveform emerges, with the classic peaks labelled I, III and V. Because the recording is picked up automatically from the nervous system while the patient lies still, BERA is the reference test for newborns, for young children who cannot perform play audiometry, for patients where a non organic or exaggerated loss is suspected, and for medico legal hearing claims that require objective evidence.
Why it matters
- It estimates hearing thresholds objectively when behavioural testing is impossible or unreliable.
- It screens the pathway from cochlea to brainstem, which matters when one ear is worse than the other or when there is tinnitus on one side only.
- It underpins early intervention: a confirmed BERA result allows a baby to be aided within the first months of life.
- It provides defensible documentation for occupational, insurance and legal hearing assessments.
Step by step
How the assessment is performed
Each stage follows established audiological protocol, and you are told what is happening before it happens.
- 1
Preparation and electrode placement
The skin at the forehead and behind each ear is gently cleaned to lower impedance, then soft electrodes are attached. Impedances are checked before recording starts, since a poor contact ruins the trace.
- 2
Settling the patient
Muscle activity is the main source of interference, so the patient must be relaxed. Babies are tested in natural sleep after a feed, and adults are made comfortable on a couch in a darkened quiet room.
- 3
Stimulus delivery
Insert earphones present clicks or frequency specific tone bursts, one ear at a time, at a set repetition rate. The system averages many thousands of sweeps to lift the response out of background noise.
- 4
Threshold search
The stimulus level is lowered in steps until wave V can no longer be identified. That lowest level is the electrophysiological threshold and it correlates closely with behavioural hearing.
- 5
Latency and waveform analysis
Absolute latencies of waves I, III and V, the I to V interpeak interval and interaural differences are measured. Delays or absent waves at high levels suggest a problem beyond the cochlea and trigger onward referral.
How to prepare
- For babies and young children, keep them awake before the appointment and bring a feed so they sleep through the recording.
- Wash hair and avoid oils, gels or braided styles that prevent electrode contact at the forehead and mastoids.
- Adults should avoid caffeine immediately before and plan to lie still with eyes closed.
- Tell us about any sedation, neurological condition or previous ear surgery.
Understanding your results
- Normal responses
- Clear wave V down to low stimulus levels with normal latencies. Hearing sensitivity and the brainstem pathway are within normal limits.
- Raised thresholds
- Wave V disappears at higher than expected levels, indicating hearing loss. Frequency specific tone burst testing then estimates the audiogram shape for a hearing aid fitting.
- Delayed or absent waves
- Prolonged interpeak intervals or an interaural latency difference point to a retrocochlear cause. We refer for ENT review and imaging with a full written report.
FAQ
Common questions
Does BERA involve needles or radiation?
Neither. Only surface electrodes that stick to the skin, like those used for an ECG.
Will my child need sedation?
Usually not. Most infants are recorded in natural sleep. Where sedation is genuinely required it is arranged medically, never casually.
Is BERA better than an audiogram?
It is different. BERA is objective but estimates thresholds, while behavioural audiometry measures what you actually perceive. We use whichever, or both, fits the clinical question.
Explore
Other tests we perform
Pure Tone Audiometry
The reference test for hearing. It maps the quietest sounds you can detect across the speech frequencies and shows whether a loss sits in the outer, middle or inner ear.
Paediatric Hearing Assessment
Age appropriate testing for babies and children, using play, toys and visual rewards to obtain reliable thresholds long before a child can describe what they hear.
Tympanometry and Impedance Audiometry
A rapid objective measure of how the eardrum and middle ear move, detecting fluid, negative pressure, perforation and ossicular problems within seconds per ear.