Introduction
ABR is a far-field, scalp-recorded summary of the first ten milliseconds of auditory signal travel. This atlas teaches the language used to read it.
The auditory brainstem response (ABR), historically called Brainstem Evoked Response Audiometry (BERA), is the average of many thousands of short scalp-recorded epochs time-locked to a brief acoustic stimulus[1]. The resulting waveform, lasting roughly 10 ms, contains a stereotyped sequence of five (occasionally seven) positive peaks. Each peak is generated by a specific structure along the path from cochlea to inferior colliculus[2].
What ABR is good for
ABR is the workhorse of objective hearing assessment. It does not require behavioural cooperation, so it is the standard test for any patient whose voluntary responses cannot be trusted — neonates, young children, sedated adults, malingerers, the comatose[3]. Its second great use is anatomical: because each wave maps to a specific generator, prolongation of an interpeak interval localises a lesion along the pathway.
What ABR is not
ABR is a brainstem signal. It samples up to the inferior colliculus and stops there. Anything happening above — thalamocortical integration, attention, speech processing, working memory — cannot be assessed with ABR alone[4]. The middle-latency response and the behavioural CAPD battery cover that territory.
The atlas in one sentence
We move from how the signal is generated, through how it is recorded and read, to nine canonical patterns of disease, and end at the tools you'll use to read them: a simulator, a comparator, a trainer, and a self-assessment quiz.