Improved Speech Perception in Cochlear Implant Users With Interleaved High-Rate Pulse Trains.

Abstract

Electrical stimulation with a cochlear implant (CI) elicits abnormally high neural synchrony, which poses significant challenges for speech perception. Previous investigations showed that constant-amplitude high-rate pulse trains (HRPs) desynchronize neural responses and improve stimulus encoding. The study objective was to investigate the effects of HRP on speech perception in adult CI users. Prospective, within-subject design. Tertiary CI center. Ten adult CI recipients. Sentence stimuli were created by modifying a basic continuous interleaved sampling (CIS) strategy (1,000 pulses per second; pps) with interleaved biphasic pulse trains (3,000 pps) on even electrodes. Institute of Electrical and Electronics Engineers sentences in quiet and in noise were tested without HRP, and with HRPs of various stimulation levels. Sentence perception in percent correct was calculated for all conditions. The highest speech perception score with HRP stimulation was defined as "max-HRP." Group analyses showed significantly improved sentence perception in background noise with HRPs (p < 0.001). There was no significant difference for sentence perception in quiet for the group. However, seven of 10 subjects experienced some benefit from HRP stimuli in quiet and the degree of HRP benefit showed significant relationships with baseline performance and age at implantation, indicating that HRP stimuli may be most beneficial for older patients or poorer performers. Significant improvement in speech perception in noise was observed with HRP stimuli. Some recipients may also benefit from HRP stimulation in quiet. Interleaved HRPs hold promise as a novel stimulation paradigm with clinical sound processing strategies to improve patient performance.