Spatial Release From Masking in Adults With Bilateral Cochlear Implants: Effects of Distracter Azimuth and Microphone Location

Abstract

Purpose The primary purpose of this study was to derive spatial release from masking (SRM) performance-azimuth functions for bilateral cochlear implant (CI) users to provide a thorough description of SRM as a function of target/distracter spatial configuration. The secondary purpose of this study was to investigate the effect of the microphone location for SRM in a within-subject study design. Method Speech recognition was measured in 12 adults with bilateral CIs for 11 spatial separations ranging from −90° to +90° in 20° steps using an adaptive block design. Five of the 12 participants were tested with both the behind-the-ear microphones and a T-mic configuration to further investigate the effect of mic location on SRM. Results SRM can be significantly affected by the hemifield origin of the distracter stimulus—particularly for listeners with interaural asymmetry in speech understanding. The greatest SRM was observed with a distracter positioned 50° away from the target. There was no effect of mic location on SRM for the current experimental design. Conclusion Our results demonstrate that the traditional assessment of SRM with a distracter positioned at 90° azimuth may underestimate maximum performance for individuals with bilateral CIs.