Site for placing an electrode in auditory brain stem Implant is:

Ref. Diseases of Ear, Nose and Throat. Pg 127   Auditory brainstem implants have three main parts: A microphone and sound processor positioned behind the ear to pick up sounds A decoding chip placed under the skin to transmit information picked up by the microphone Electrodes connected directly to the brainstem(4th ventricle recess), when stimulated, alert you to sound