Fellow University of North Carolina Chapel Hill, North Carolina
Educational Objective: At the conclusion of this presentation, the participants should be able to describe the development of binaural hearing abilities for cochlear implant recipients with unilateral or asymmetric hearing loss and variables that may contribute to differences in improvement.
Objectives: To assess development of binaural hearing abilities for cochlear implant (CI) users with unilateral hearing loss (UHL) or asymmetric hearing loss (AHL) with 5 years of CI listening experience. Study Design: Prospective cohort.
Methods: Adults with UHL or AHL underwent cochlear implantation as part of an FDA approved clinical trial. Binaural hearing abilities were assessed using AzBio sentences with 10 talker masker. Spatial release from masking (SRM) was calculated as the difference in scores when the masker was offset to the CI ear (SRMci) and contralateral ear (SRMcontra) relative to the co-located condition (0 degrees). Tasks were completed preoperatively and at intervals up to 5 years post-activation.
Results: 20 UHL and 19 AHL participants completed the clinical trial endpoint (1 year post-activation). Linear mixed models showed a significant main effect of interval and group for SRMcontra. There was a significant interaction of interval and group, with UHL participants reaching asymptotic performance within the initial months of CI use and AHL participants demonstrating continued growth in binaural abilities out to 5 years. There was no correlation between change in SRM and contralateral hearing thresholds (p=0.060), but there was a significant correlation with age (p=0.005).
Conclusions: CI recipients with UHL and AHL experience improved SRM with long term device use. The time course of improvement varied by cohort, with the UHL cohort reaching early asymptote and the AHL cohort continuing to improve. Differences were likely driven by differences in age at implantation, with AHL participants implanted at an older age.