An Auditory Brainstem Response test (ABR) evaluates how well the sounds travel along the hearing nerve pathways to the brainstem. An ABR may be recommended for a variety of reasons. It can be used to determine the integrity of the auditory pathway, or to estimate hearing thresholds in newborns, older children and adults who cannot perform reliably on a behavioural hearing test.

Recording electrodes are placed onto the head and soft foam tips are inserted into the ear canals. While the patient is sleeping, quiet clicking sounds are delivered through the foam tips. Nerve responses elicited by the sound are picked up by the electrodes and then passed on to a computer to be recorded. The recordings are analysed to determine if they fall within normal limits. The results are then reported to the patient's GP or to the Ear, Nose and Throat (ENT) specialist if further medical evaluation is required.

Depending on the age and compliance of the patient, an ABR may be performed either during natural sleep or, in rare cases, under general anaesthetic.