Cochlear Implant Users can Effectively Combine Place and Timing Cues for Pitch Perception

Objectives: The study objective was to characterize cochlear implant (CI) pitch perception for pure, complex, and modulated tones for frequencies and fundamental frequencies in the ecologically essential range between 110 and 440 Hz. Stimulus manipulations were used to examine CI users' reliance on stimulation place and rate cues for pitch discrimination.Design: The study was a within-subjects design with 21 CI users completing pitch discrimination measures using pure, complex, and modulated tones. Stimulus manipulations were used to test whether CI users have better pitch discrimination for low-pass compared with high-pass filtered harmonic complexes, and to test whether they have better pitch discrimination when provided a covarying place cue when listening to amplitude-modulated tones.Results: Averaged across conditions, participants had better pitch discrimination for pure tones compared with either complex or amplitude-modulated tones. Participants had better pitch discrimination for low-pass compared with high-pass harmonic complexes and better pitch discrimination for amplitude-modulated tones when provided a covarying place cue.Conclusions: CI users integrate place and rate cues across the ecologically essential pitch range between 110 and 440 Hz. We interpret the observed better pitch discrimination for low-pass compared with high-pass filtered harmonics complexes, and for amplitude-modulated tones when provided a covarying place cue, as evidence for the importance of providing place-of-excitation cues for fundamental frequencies below 440 Hz. Discussion considers how such encoding could be implemented with existing devices.

Automated summary

This study aimed to characterize cochlear implant users' pitch perception for different types of tones and test their reliance on stimulation place and rate cues for pitch discrimination. The results showed that CI users integrate place and rate cues across the ecologically essential pitch range. They had better pitch discrimination for low-pass filtered harmonic complexes and amplitude-modulated tones when provided a covarying place cue.