Temporal processing in cochlear implants

Abstract

Psychophysical experiments were conducted to assess the temporal processing of patients with multichannel cochlear implants. Threshold and suprathreshold temporal integration were similar to normals, with integration time constants of 100–200 ms and 50–100 ms, respectively. Gap detection decreased from 60 ms near threshold to 1–2 ms for loud stimuli, similar to normals at high frequencies. Forward masking decreased as the delay of the signal from the masker was decreased, with a time course similar to or slightly longer than normals. All of these measures indicate that temporal integration and adaptation in implants are similar to normals, indicating an intact central mechanism. One major difference between implants and normals was in the sensitivity to details of the temporal waveform. Normals hear little or no difference as a function of phase within a complex waveform, but the same stimuli can cause large perceptual differences for implant patients. Implications for implant processor design are considered. [Work supported by NIH.]