Simulated Phase-Locking Stimulation: An Improved Speech Processing Strategy for Cochlear Implants

Abstract

The continuous interleaved sampling (CIS) speech-processing strategy has been widely used for cochlear implants to extract speech envelope information without preserving phase information. In this study, a novel simulated phase-locking stimulation (SPLS) strategy, which detects zero-crossing times of the narrow-band signal of each band, was developed to extract both phase and amplitude-envelope information from a bank of frequency bands of speech sounds. The advantage of the SPLS strategy over the CIS strategy was confirmed by the results of our psychophysical experiments, showing that normal-hearing Chinese listeners’ performance in recognizing SPLS-processed Chinese speech was significantly better than their performance of recognizing CIS-processed Chinese speech under quiet, noise-masking, or speech-masking conditions. Thus, the results suggest that if the SPLS strategy is used to modulate the interval of electrical stimulation pulses in cochlear-implant devices according to extracted phase information, the speech-processing functions of cochlear implant devices would be improved for Chinese cochlear implant users.

Analog IC Design Techniques for Nanopower Biomedical Signal Processing

“…In tins strategy, tlie 2'"' layer Is put on to|i of tlie fi" layer to introduce a phase locking amplitude modidated pidse train [114]. At tlie moment that the input signal crosses zero from negative to positive values, a pulse is generated and will be modulated with the momentary value of the envelope at that moment to create the stuniilation pidse train.…”