Determination of Optimum Parameters for Cochlear Implants Speech Processors by Using Objective Measures

Abstract

In a cochlear implant (CI) speech processor, several parameters such as channel numbers, bandwidths, rectification type, and cutoff frequency play an important role in acquiring enhanced speech. The effective and general purpose CI approach has been a research topic for a long time. In this study, it is aimed to determine the optimum parameters for CI users by using different channel numbers (4, 8, 12, 16, and 22), rectification types (half and full) and cutoff frequencies (200, 250, 300, 350, and 400 Hz). The CI approaches have been tested on Turkish sentences which are taken from METU database. The optimum CI structure has been tested with objective quality that weighted spectral slope (WSS) and objective intelligibility measures such as short-term objective intelligibility (STOI) and perceptual evaluation of speech quality (PESQ). Experimental results show that 400 Hz cutoff frequency, full wave rectifier, and 16-channels CI approach give better quality and higher intelligibility scores than other CI approaches according to STOI, PESQ and WSS results. The proposed CI approach provides the ability to percept 91% of output vocoded Turkish speech for CI users. © 2022, TUBITAK. All rights reserved.