Preliminary evaluations of cochlear implantees using a wearable CIS processor

Abstract

Each channel of a continuous‐interleaved‐stimulation (CIS) sound processor uses the compressed envelope of its bandpass‐filtered output to modulate biphasic current pulses that are delivered to an intracochlear electrode. Pulses are interleaved across channels to avoid simultaneous field interactions, and pulse rates are high (∼2000 pps/channel) to preserve temporal waveform cues. Using up to six monopolar electrodes directly accessible with the Ineraid implant, this strategy has shown considerable promise in acute evaluations conducted in the laboratory [Wilson et al., Nature 352, 236–238 (1991)]. In collaboration with a group in Innsbruck, a prototype portable real‐time system has been developed (based on a DSP56001) that can realize some CIS implementations. Two subjects with 9 years of experience using the Ineraid analog sound processor are now wearing the CIS system on a full‐time basis. After several weeks, one subject prefers the CIS strategy; however, objective measures of speech reception show no gains (re: the Ineraid processor). The second subject shows large gains with CIS and some evidence of continuing improvements. Without lipreading, he scores near perfect on relatively difficult (IEEE/Harvard) sentences in quiet; for speech reception in noise, he shows a deficit of 7 dB re: normal‐hearing listeners. [Work supported by NIH.]