Combined Within-Channel Forward and Backward Masking in Cochlear-Implant Listeners (de)
* Presenting author
Abstract:
Cochlear implants (CIs) restore basic hearing in the profoundly hearing-impaired or deaf by converting acoustic input into sequences of electric pulses that stimulate the auditory nerve through an intracochlear array of electrodes (or channels). Many clinical stimulation strategies rely on the transmission of amplitude modulation of constant-rate pulse train carriers. Typically, the carrier pulse rates are neither matched to the place of stimulation nor the listener-specific response properties of the auditory nerve. Hence, it is likely that many stimulation pulses contribute little to the overall percept, that is, they are masked. More severely, even masked pulses might interact across electrodes and confound the effectiveness of the non-masked pulses. Recently, Lamping et al. [Hear. Res. 391, 107969 (2020)] applied a model of combined forward and backward masking from normal hearing to CI stimulation sequences to reduce within-channel masking. They observed a significant improvement of speech intelligibility in noise. In this contribution, we measured combined within-channel masking in CI listeners at two electrodes using unmodulated maskers at two masker rates (200 and 1000 pulses/s). The psychophysical results were used to fit, per CI listener, a model of combined within-channel masking. Interim results as well as future model applications will be discussed.