Design and Initial Clinical Test Results of a Simplified Cochlear Implant System

Abstract

A simplified cochlear implant system would be appropriate for widespread use in developing countries. Such a system has been developed as an academia-industrial project. The system implements 8 channel Continuous Interleaved Sampling (CIS) strategy. A generic Digital Signal Processing (DSP) chip is used for the processing with FFT filtering. Data derived from the processing are transmitted through an inductive link using Pulse Width Modulation (PWM) encoding and Amplitude Shift Keying (ASK) modulation. The same link is used in the reverse direction for backward telemetry of electrode and system information. A custom receiver-stimulator chip has been developed that demodulates incoming data using pulse counting and produces charge balanced biphasic pulses at 1000 pulses/s/channel. This chip is encased in a titanium package. An intra-cochlear electrode array with 16 ball-shaped stimulating contacts was also fabricated. Speech perception tests with Ineraid patients to evaluate the effectiveness of the system were performed at the Center for Auditory Prosthesis Research at the Research Triangle Institute (RTI) in the United States.