A Possible Way to Improve the Quality of Speech Perception by Increasing the Number of Electrodes in a Cochlear Implant from 8 to 22

Abstract

A cochlear implant (CI) helps a person with auditory receptor pathology restore the ability to hear and understand speech. The partial loss of the information about the frequency and loudness of the audio signal is the main difference from the natural sound perception. CIs of various types differ in the number of stimulated electrodes: 12, 16, 20, or 22. The quality of speech perception is significantly improved by increasing the number of stimulated electrodes from 4 to 7 and almost does not change with a further increase in the number of electrodes from 8 to 22. When speech is perceived in all types of CI, 3 to 6 adjacent electrodes are usually stimulated simultaneously. When a single electrode is stimulated, the CI user hears a sound with a single pitch. When two adjacent electrodes E(n) and E(n+1) are simultaneously stimulated, a virtual frequency channel (VFC) is formed, and the CI user hears a sound with an intermediate pitch {Z(n)+Z(n+1)}/2, provided that the adjacent electrodes on the right and left are not stimulated. When three or more adjacent electrodes are simultaneously stimulated, the CI user hears a sound with the same pitch, which depends on the distance from the electrode with the largest amplitude of stimulating pulses to the apex of the cochlea. There was no suggestion as to why the quality of speech perception does not improve when the number of electrodes increases from 8 to 22 in the scientific literature for the period from 1997 to 2019. This article proposes a method for adjusting the mode electrodes stimulation, which creates conditions for the formation of virtual frequency channels. The CI user will be able to hear a greater number of sounds of various pitch. A method for correcting the algorithm for controlling the stimulation of electrodes, which can be used in any type of CI, is proposed.