The auditory brainstem response (ABR), also called brainstem evoked response audiometry (BERA), is an auditory evoked potential extracted from ongoing electrical activity in the brain and recorded via electrodes placed on the scalp. The measured recording is a series of six to seven vertex positive waves of which I through V are evaluated. These waves, labeled with Roman numerals in Jewett and Williston convention, occur in the first 10 milliseconds after onset of an auditory stimulus. The ABR is considered an exogenous response because it is dependent upon external factors.

The auditory structures that generate the auditory brainstem response are believed to be as follows:

• Wave I through III – generated by the auditory branch of cranial nerve VIII and lower
• Wave IV and V – generated by the upper brainstem
• More in depth location – wave I and II originates from the distal and proximal auditory nerve fibers, wave III from the cochlear nucleus, IV showing activity in the superior olivary complex, and wave V is associated with the lateral lemniscus.