Multichannel auditory brain stem implant: case studies comparing fitting strategies and results.

A new 8-electrode prosthesis has been developed for individuals deafened by bilateral auditory nerve tumors (neurofibromatosis-2). Twelve patients have received the multichannel auditory brain stem implant at House Ear Institute since 1992, 11 of whom receive useful auditory sensations. Processor fitting includes scaling and ranking of electrode-specific pitch sensations, and determination of any nonauditory sensations. Two representative patients differing in experience and number of usable electrodes are compared in terms of range of auditory sensations and speech perception performance. An inexperienced patient with two electrodes using a new speech-processing strategy (Speak) performed comparably to an experienced patient with six electrodes using an earlier feature-extraction processor.