2. Ages between 12 months and 85 years. 3. Evaluation of internal ear anatomy performed by tomography and resonance magnetic, where normal cochlea and internal auditory canals are evidenced normal. 4. Patients in which any implant of the Cochlear company is used: CI512, CI522 or CI532 with chipset CIC4 or higher. 5. Complete insertion of electrodes through round window, round window enlarged or cochleostomy, via posterior tympanotomy using the technique universally known as "minimally traumatic surgery"