Pitch Sensitivity in Electric Hearing: Dual-Electrode Stimulation and Peripheral Interference
* Presenting author
Abstract:
Cochlear-implant (CI) listeners show impaired pitch perception compared to normal-hearing listeners. Peripheral channel interference is assumed to be a significantly limiting factor, being partly responsible for differences in sensitivity between single- and multi-electrode stimulation. In our work, pitch sensitivity for dual-electrode stimuli was measured in CI listeners using a discrimination task. The stimuli consisted of a target electrode (located in the center of the array) and a flanker electrode (located on either side of the target). Two interference conditions were tested. To create maximal interference, narrow flankers were selected to be adjacent to the target. To create minimal interference while being as close as possible to the target, wide flankers were selected based on the listener’s forward-masked spatial tuning curve. Per electrode, stimuli were either unmodulated 100-pps pulse trains or 1000-pps pulse trains with a 100-Hz amplitude modulation. The modulated stimuli were tested both with and without additional pulses placed with short inter-pulse intervals at modulation peaks. The delay between target and flanker was systematically varied in the range of one (modulation) period. The results showed a systematic effect of the delay that seemed to depend both on the amount of interference and the type of stimulus.