Contralateral unmasking for single-sided-deafness cochlear-implant users with shifted frequency assignments to reduce interaural place mismatch

Abstract

For cochlear-implant (CI) users with single-sided deafness (SSD), standard clinical programming yields interaural place-of-stimulation mismatch, because the electrode array does not reach the apex. This mismatch might degrade spatial-hearing abilities. This study examined whether acutely presented alternative frequency-to-electrode assignments (“remapping”), designed to reduce mismatch, could improve the use of two ears together to perceptually separate competing talkers. Remapped frequency assignments were derived from computed-tomography scans of intracochlear electrode locations or psychophysical tuning curves for interaural time-difference discrimination. Contralateral unmasking was measured by presenting target speech (closed-set corpus) to the acoustic ear and two same-sex competing talkers to just the acoustic ear or to both ears. Preliminary results (N = 8/15 planned subjects) show that for seven subjects with small (≤3-dB) initial binaural benefit, remapping yielded a small but significant (0.5-dB mean) increase in binaural benefit. Remapping was detrimental for the one subject with large (6-dB) initial binaural benefit. Possible longitudinal effects and tradeoffs with other SSD-CI hearing benefits that could be affected by remapping are discussed. [The views expressed in this abstract 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.]