Effect of Gap-interleaved Stimulation Paradigms in Speech Perception Performance of Experienced Cochlear Implant Recipients: a Single-centre, Randomised Controlled Single-blinded Study

Cochlear implants (CI) are used to help patients with severe to profound hearing loss regain auditory perception by electrical stimulation of the auditory nerve. The electrical stimulation consists of trains of charge balanced, biphasic current pulses. For each patient, individual stimulation parameters (perception threshold, most comfortable level - MCL) are determined for each electrode during fitting sessions. However, an important parameter, pulse duration, cannot be individualized for each electrode. There are certain circumstances where it would be advantageous to have the possibility of introducing variable pulse durations into the fitting strategy (e.g., optimization of energy consumption, development of combined cochleo-vestibular implants). However, since in current CI systems pulses are transmitted sequentially, introducing varying pulse widths would also introduce "gaps" (zero-stimulation periods) into the stimulation profile. The influence of such auditory gaps on speech recognition and on the quality of hearing has not been explored yet, but can be investigated in current CI users. The objective of this study is to investigate the impact of time-fixed gaps (zero-stimulation periods) in the cochlear stimulation strategy on speech performance and hearing quality.