An invasive, hand-held, thin instrument (probe) with a distal electrode intended for preoperative and/or intraoperative delivery of electrical stimulation to the cochlear (auditory) nerve to assess nerve function prior to implantation of a cochlear implant (CI). It may be used during open surgery or via transtympanic approach and conducts electrical current via connection to an external electrical pulse generator; it is used in conjunction with an evoked auditory brainstem response (eABR) recording system. This is a single-use device.