The cochlear implant is a clinically useful prosthesis for selected deaf patients who cannot benefit from a hearing aid. However, the poor speech discrimination and limited dynamic range generally achieved with the implant indicate that there are a number of basic and applied questions to be answered. Using acoustically and electrically elicited Auditory Brainstem Response (ABR) techniques, we have established an animal model (guinea pig) to help us answer some of these questions. We are presently studying the effect of electrode location on the electrical ABR. The single active cochlear electrode is located in either the basal or apical turn. The return electrode locations are the temporalis muscle, the eustachian tube, or the bulla. By choosing the proper polarity of the biphasic stimulating pulse, the electrical artifact can be minimized and virtually all of the ABR can be observed. Normative data for the electrical ABR and preliminary results of the electrode placement study will be presented.