Brainstem evoked response audiometry (BERA) is a neurophysiological test performed in children with hearing loss and delayed speech. It evaluates the hearing threshold and diagnoses retrocochlear or cochlear lesions, which act as a screening test for deafness in children below five years. It is difficult to test in adults.

The test requires one hour to one and a half hours to perform, whereas if anaesthesia needs to be given to the child, it may exceed up to four hours.

It can help determine the rate at which an impulse reaches the brain and whether it gets delayed to reach the brain, which can help indicate the occurrence of hearing loss. Furthermore, the cause of hearing loss and the hearing threshold can also be determined. It is also used to diagnose asymmetric hearing impairment due to various neurological disorders and tumours.

The electrical activity of the brain is measured in electroencephalogram (EEG), whereas BERA is a particular type of EEG which measures the electrical activity of the brain but is time-dependent, that is, the sound stimulus waves appear after a specific time in BERA.

Small sensors are stuck on the scalp and ears of the baby. Then headphones are put on his or her ears that sends different sounds to the inner ear, which then travel to the brain. These waves are measured by three electrodes, namely reference, ground and active electrode, in the form of electric signals. If signals do not reach the brain properly, then the child might have impaired hearing.