Auditory brainstem response (ABR), also known as brainstem evoked response (BSER) is an electrical signal evoked from the brainstem of a human or other mammal by the presentation of a sound such as a click.
Particularly notable for its use with newborn infants, auditory brainstem response audiometry or Brainstem evoked response audiometry (BERA), is a screening test to monitor for hearing loss or deafness. It is employed to assess the functions of the ears, cranial nerves, and various brain functions of the lower part of the auditory system, prior to the child developing to the point of describing a possible hearing problem. A brief click or tone pip is generated from an earphone or headphone and the elicited neuronal action potentials are measured by surface electrodes, typically placed at the vertex of the scalp and ear lobes. The potential of the signal in microvoltage is averaged and charted against the time (millisecond), similarly to an electroencephalography (EEG).