Improving Outcomes of Single-Sided Deaf Cochlear Implant Users by Reducing Interaural Frequency and Loudness Mismatches through Device Programming

The study aimed to improve outcomes in Nucleus cochlear implant (CI) recipients with single-sided deafness (SSD) by reducing interaural frequency and loudness mismatches through device programming. In Experiment 1a, a modified frequency allocation table (FAT) was created to better match the tonotopicity of the contralateral ear and reduce interaural frequency mismatch. Twenty experienced SSD-CI users completed localization and speech recognition tests with their everyday FAT. Tests were repeated after 6 weeks’ use of the modified FAT. Participants compared both FATs for 2 weeks before being tested again with each. For 10 newly implanted SSD-CI recipients (Experiment 1b), Group A was programmed with the manufacturer's default FAT and Group B with the modified FAT at activation. Speech recognition and localization were completed, after 6 weeks’ use of each FAT. Participants then compared both FATs before testing with each. In Experiment 2, 15 experienced SSD-CI users were evaluated with their everyday program and a modified loudness program, which was created to obtain audibility of ∼20 dB HL from 0.25 to 6 kHz and balanced loudness between ears. Three test sessions occurred, resembling Experiment 1a. Experienced participants in Experiments 1a and 2 showed significant improvement in one speech-in-noise task with a modified program compared to the everyday program. Newly implanted recipients showed no significant difference in results between FATs. Results indicate that modified programs, created to reduce interaural mismatches, may improve outcomes. The first month after activation might be too early to compare FATs as SSD-CI recipients are adjusting to electric hearing.