Hardware Simulation of Cochlear Implant System

Abstract

Cochlear implant systems have been developed and used for many patients, however, the processing system is still imperfect in transferring speech information. Usually, processing is evaluated with the cooperation of implanted patients, but this implies difficulties and limits the application. Obviously the speech processor needs to be improved because it extracts only limited speech features. In order to accelerate improvements, we developed acoustic simulator hardware which is intended to imitate the stimulation received by implanted patients. It consists of a set of active filters with operational amplifier circuits, like the original speech processor. Hard-wired analog circuits are used to achieve real time examination on various sources of speech material. The acoustic process and electro-neuro-physiological process in action around the electrode implanted into the cochlea and haircell nerve were with band pass filters and stimulation pulse trains which are amplitude modulated. This system has been evaluated under several conditions, such as monosyllables, words, and sentences. Comparison with other reports, our results have shown that this hardware simulation approximately matches the articulation score of implanted patients. This simulator developed here provides a useful tool for evaluation of acoustic processing and parameter coding schemes for cochlear implant systems.