Speech recognition of adult cochlear implant users with unilateral hearing loss: Default versus place-based mapping procedures

Introduction: Early speech recognition with a cochlear implant (CI) may be influenced in part by the mapping procedure used to assign the bandpass filters. This brief report compared the speech recognition of CI users with unilateral severe-to-profound sensorineural hearing loss (UHL) who were mapped with either a default or individualized, place-based mapping procedure. Methods: Participants were 19 newly implanted adults with UHL who were randomized at activation to listen with either a default map or place-based map. Filters for the default maps were 70-8500 Hz. Filters for the place-based maps were individualized to match the center frequency with the cochlear place frequency for electrodes in the low- and mid-frequency regions. Speech recognition was assessed at 1 and 6 months post-activation. Word, phoneme, and vowel recognition were assessed in the CI-alone condition. Masked speech recognition was assessed in the bilateral condition. Results: For vowel recognition and masked speech recognition (masker towards the non-implanted ear), performance was better for the place-based group than the default group at the 6-month interval. There were no significant differences in scores for CNC words and phonemes, or masked speech recognition when the masker was co-located with the target or towards the implanted ear. Conclusion: Preliminary results support the idea that adult CI users with UHL experience better speech recognition for some measures with place-based maps than default maps, and that differences may be apparent after several months of CI use.