An adaptive envelope compression strategy for speech processing in cochlear implants

Hearing-impaired patients have limited hearing dynamic range for speech perception, which partially accounts for their poor speech understanding abilities, particularly in noise. Wide dynamic range compression aims to compress speech signal into the usable hearing dynamic range of hearing-impaired listeners; however, it normally uses a static compression based strategy. This work proposed a strategy to continuously adjust the envelope compression ratio for speech processing in cochlear implants, named adaptive envelope compression (AEC) strategy. This AEC strategy aims to keep the compression processing as close to linear as possible, while still confine the compressed amplitude envelope within the pre-set dynamic range. Vocoded simulation experiments showed that, when narrowed down to a small dynamic range, the intelligibility of AEC-processed sentences was significantly better than those processed by static envelope compression. This makes the proposed AEC strategy a promising way to improve speech recognition performance for implanted patients in the future.