An acoustic model of a multiple-channel cochlear implant.

A set of bandpass filtered, pulsed noise stimuli presented to three normally hearing subjects was found to have psychophysical properties similar to those of a set of pulsed electrical stimuli presented to two cochlear implant patients. Identical procedures were used to compare the performances of the two groups of subjects in the following tasks: (a) pulse rate difference limen measurements, (b) pitch scaling for stimuli differing in pulse rate, (c) pitch scaling and categorization of stimuli differing in filter frequency or electrode position, and (d) similarity judgments of stimuli differing in pulse rate and filter frequency or electrode position. By choosing the parameters of the acoustic stimuli appropriately, a high level of agreement between the two sets of results was achieved. Electrical stimuli on electrodes at different sites in the cochlea were matched with pulsed noise passed through bandpass filters with different center frequencies. Matching was achieved for equal electrical and acoustic pulse rates.