Pulsatile Gaussian-Enveloped Tones (GET) for cochlear-implant simulation

Acoustic simulation of cochlear implants (CIs) allows studies of not only perceptual performance in normal-hearing listeners but also relative contribution of spectral and temporal cues to speech recognition. Different from conventional simulations using continuous sinusoidal or noise carriers, this study employs pulsatile Gaussian-enveloped tones (GETs) to simulate several key features in modern CIs. Subject to the time-frequency uncertainty principle, the GET has a well-defined tradeoff between its duration and bandwidth. In theory, the key pulsatile features of CI electric stimuli could be simulated in the analysis part of a pulsatile acoustic model. We hypothesized that a GET vocoder could transmit speech information similar to actual CIs. In an experiment, 900-Hz/channel pulse trains were directly mapped to 900-Hz GET trains to simulate the maxima selection and amplitude compression of a widely-used n-of-m processing strategy, or the Advanced Combination Encoder. The simulated and actual implant performance of speech-in-noise recognition was similar in terms of the overall trend, absolute mean scores, and standard deviations. The results suggest that the pulsatile GET can serve as an alternative to simulating modern CIs in terms of simulating pulsatile and several other key features of CI stimuli and, more importantly, producing similar speech perception patterns. Investigation is needed to further evaluate the performance of the GET in different acoustic and electric configurations.(c) 2023 Elsevier Ltd. All rights reserved.