OBJECTIVES: I. Define the tonotopocity of multichannel brain stem stimulation and use this information to better program the auditory brain stem implant for an individual.

II. Optimize device fitting by combining monopolar and bipolar stimulation, and individual psychoacoustic channels for each patient, to increase the number of usable information channels for each patient and reduce or eliminate undesirable side effects.

III. Evaluate performance and learning effects using optimized fitting procedures.

PROTOCOL OUTLINE: Patients undergo surgery to remove the first side or second side tumor, during which the multichannel auditory brain stem implant is implanted. Initial stimulation is conducted 4-6 weeks after surgery.

Patients are followed every 3 months for the first year, then annually thereafter.

PROTOCOL ENTRY CRITERIA:

--Disease Characteristics-- Confirmed diagnosis of neurofibromatosis type 2 Scheduled to undergo first side or second side tumor removal First side implantation performed only on patients with onset of symptoms prior to age 40 --Prior/Concurrent Therapy-- If a nonfunctional auditory brain stem implant (ABI) is present (implanted during the removal of a first side tumor), a multichannel ABI may be implanted during the removal of a second side tumor --Patient Characteristics-- English is the primary language