auditory brainstem response auditory brainstem response 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.