The Brainstem Auditory Evoked Potential provides information about the auditory brainstem pathways. In a BAEP, the potential changes are measured on the scalp. The potential fluctuations are caused by electrical events occurring in the cochlea, eighth nerve, and auditory pathways in the brainstem whenever impulses in response to an auditory stimulus travel to the cerebral cortex via the acoustic system.
Although the recording and stimulus parameters change between clinics, surface recording electrodes are usually placed on the mastoid or earlobe, at the vertex, and the forehead as a Ground electrode. Testing of each ear using around 70dBHL clicks is repeated until a response is replicated at least once. Ears are tested monaurally with a white-band masking noise applied to the contralateral ear. The BAEP consists of seven peaks and is measured in the 10msec following an acoustic stimulus (usually a click).
Here is an example of a brainstem auditory evoked potentia