The Importance of Pitch Discrimination in Cochlear Implant Users
Wang et al (2011) evaluated 19 adult cochlear implant (CI) users and 10 normal hearing listeners with regard to their perception of tone/pitch. CI users demonstrated a mean threshold for pitch discrimination of 5.5 semitones (with a range from 0.8 semitones to 19.6 semitones). People with normal hearing demonstrated average thresholds of 0.4 semitones. With regard to CI users, the authors stated electrode position and surviving spiral ganglion cells likely impact pitch perception and noted a strong correlation between CI users tone perception performance and their pitch discrimination threshold. Zeng et al (2014) report people with normal hearing can discern 1,400 frequency differences from 20 to 20,000 Hz while CI users typically have fewer than two dozen discriminable electrode steps available.
Kenway et al (2015) reported their observational study of 22 CI patients’ pitch-ranking ability as a function of electrode position. All three major CI manufacturers were represented (10 Med-El users, 8 Advanced Bionic users, and 4 Cochlear users). The authors note that 12 CI users were “poor performers” and 10 were “excellent performers” based on their Bamford-Kowal-Bench (BKB) results. Following measurements of “threshold and comfort levels, and loudness balancing across the array, all patients underwent thorough pitch-ranking assessments at 80 percent of comfort levels….”
Kenway et al concluded that accurate pitch-ranking seems to be an independent factor and predictor with regard to overall CI outcome. Indeed, they report pitch-ranking accounts for some 44 percent or variance in CI subjects, and a high prevalence of pitch anomalies were present in poor performers. One of their conclusions states that “ability to pitch rank accurately is an independent predictor of overall performance, even after adjustment for age, duration of deafness, and time since implantation.”
For More Information, Recommendations, and References
Kenway B, Tam YC, Vanat Z, Harris F, Gray R, Birchall J, Carlyon R, Axon P. (2015) Pitch Discrimination—An Independent Doctor in Cochlear Implant Performance Outcomes. Otology & Neurotology 36:1472-1479.
Wang W, Zhou N, Xu L. (2011) Musical Pitch and Lexical Tone Perception with Cochlear Implants. International Journal of Audiology 50:270-278.
Zeng FW, Tang Q, Lu T. (2014) Abnormal Pitch Perception Produced by Cochlear Implant Stimulation. Plos One 9(2):e88662.