Contemporary cochlear implants (CIs) use cathodic-leading symmetric biphasic (C-BP) pulses for electrical stimulation. It remains unclear whether asymmetric pulses emphasizing the anodic or cathodic phase may improve spectral and temporal coding with CIs. This study tested place- and temporal-pitch sensitivity with C-BP, anodic-centered triphasic (A-TP), and cathodic-centered triphasic (C-TP) pulse trains on apical, middle, and basal electrodes in 10 implanted ears. Virtual channel ranking (VCR) thresholds (for place-pitch sensitivity) were measured at both a low and a high pulse rate of 99 (Experiment 1) and 1000 (Experiment 2) pulses per second (pps), and amplitude modulation frequency ranking (AMFR) thresholds (for temporal-pitch sensitivity) were measured at a 1000-pps pulse rate in Experiment 3.
A-TP pulses led to lower VCR thresholds than C-BP pulses at 1000 pps, suggesting improved place-pitch sensitivity with anodic-centered stimulation.
Detection thresholds, MCLs, VCR thresholds, and AMFR thresholds were consistently higher on basal electrodes across all experiments.
A-TP pulses may improve spectral coding for CI users, especially those with peripheral process degeneration indicated by stronger polarity effects.