Non-sensory biases in a pitch-discrimination task for bilateral and single-sided deafness cochlear-implant listeners

Abstract

Matching the interaural place of stimulation is likely to improve binaural processing for bilateral (BI) and single-sided deafness (SSD) cochlear-implant (CI) listeners. Although pitch matching can be used to estimate interaural mismatch for these listeners, non-sensory biases (e.g., responding to the test-frequency range rather than interaural pitch comparisons) could influence the accuracy of place-match estimates. This study evaluated pitch discrimination as a method of estimating the relative interaural places of stimulation for individual CI electrodes for BI-CI and SSD-CI listeners. Three different frequency ranges, and randomization of the stimulus presentation across reference electrodes, were used to measure non-sensory biases. Results showed substantial frequency-range effects for the majority of reference electrodes tested for both listener groups, shifting place-match estimates by as much as about 7 mm for some listeners. Reference-electrode randomization affected a smaller proportion of the estimates, producing shifts of 2-3 mm or less. These findings suggest that pitch discrimination might not reliably estimate relative interaural place of stimulation for BI-CI and SSD-CI listeners. [The views expressed in this article are those of the authors and do not reflect the official policy of the Department of Army/Navy/Air Force, Department of Defense, or U.S. Government. Funding: NIH-NIDCD R01-DC-015798 (Goupell/Bernstein).]