Auditory performance with simultaneous intracochlear multichannel stimulation.

Different sound processing strategies are used in the various cochlear implant designs. This report presents auditory data on 35 patients implanted at the University of Utah from April 1984 to April 1989. A multichannel monopolar electrode system is inserted intracochlearly. During daily use and auditory performance testing, four electrodes receive simultaneous input. The incoming acoustic signal is amplified and routed to the different electrodes through a band-pass filter system. Mean pure-tone performances were: 500 Hz-29.6 +/- 9.4 dB; 1000 Hz-23.5 +/- 13.2 dB; 2000 Hz-25.4 +/- 9.6 dB; 4000 Hz-32.1 +/- 11.5 dB; and 6000 Hz-42.2 +/- 7.7 dB. Audio-only CID sentence testing showed 51.4% of patients scoring better than 60% and 40% scoring better than 80%. The percutaneous pedestal is well tolerated; patients have had the systems in place for 13 and 15 years.