Procedure
Unaided detection thresholds in the implanted ear were measured behaviorally using pure-tone stimuli presented over insert earphones at each interval. A low-frequency pure-tone average (LFPTA) was calculated from the unaided detection thresholds at 125, 250, and 500 Hz.Participants were fit with the ear-level Sonnet2For participants randomized to listen with a default map, the electric filter frequencies were generated by the clinical software. The software assigned the low-frequency filter associated with the most apical electrode contact as the frequency where the unaided detection threshold exceeded 65 dB HL (the acoustic cutoff frequency). The remaining mid- to high-frequency information was logarithmically distributed across the active channels.For participants randomized to listen with a place-based map, the electric filter frequencies were assigned to align low- to mid-frequency information with the cochlear place frequencies. Postoperative CT imaging was obtained for all cases using a Morita cone-beam CT scanner, and the image was uploaded to the OTOPLAN software (CAScination AG and MED-EL Corporation). Two reviewers manually identified cochlear anatomical landmarks (e.g., modiolus and round window) and individual electrode contacts for each CT image; those landmarks were used by the software to calculate the AID for each electrode contact, as previously described (Speech recognition was assessed using tasks of vowel and word recognition. Vowel recognition tasks have been shown to be sensitive measures of the influence of electric mismatches on speech recognition with a CI alone (