Abstract
Several cochlear implant systems have been released for commercial use. They are of various types: analog or digital stimulation, extracochlear or intracochlear stimulation, single electrode or multiple electrodes, and single channel or multiple channels.
The type of the implants, especially their speech-processing capacities plays an important role in speech discrimination. In this study, implants are compared in relation to some theories of auditory physiology. They utilize frequency- or placepitch, but they do not yet simulate phase locking of auditory nerve fibers to elicit pitch perception.
To make good use of the auditory brain's formant extracting activity, 10-15 independent speech-processing channels are thought to be essential.
Research on the auditory tract under electrical stimulation is expected to improve the quality of hearing with cochlear implants.
