Speech Perception Outcomes with the Anatomy-Based Fitting Map among Experienced, Adult Cochlear Implant Users: A Longitudinal Study.

Introduction: Anatomy-based fitting (ABF), a relatively new technique for cochlear implant (CI) programming, attempts to lessen the impact of the electrode insertion location-related frequency-to-place mismatch (FPM). This study aimed to compare vowels and consonant perception in quiet and in noise among experienced adult CI users using the ABF and the regular, conventional-based fitting (CBF) map (pre-ABF) over 6 months. Methods: Nine ears from eight experienced adult CI users were included in the experimental and longitudinal research. Using surgical planning software called Otoplan, postoperative computed computed tomography scans were used to determine the locations of intracochlear electrodes and their angle of insertion. The anatomy-based frequency bands were produced by Maestro 9.0 CI fitting software using the Otoplan data. Nonsense syllables with consonant-vowel-consonant (CVC) recognition scores in quiet and noise (+5 dB SNR) were compared at baseline, 3, and 6 months after ABF. The vowels involved were /a, i, u/, while the consonants were voiced /b, d, g/ and voiceless /p, t, k/ plosives. Speech pieces were presented at 30 dB SL in a sound-treated room through a loudspeaker positioned at 0° azimuth. Results: On average, the ABF maps shifted center frequency ranging from 0.46 semitones (0.04 octave) at (E12) to 23.94 semitones (1.99 octave) at (E1) as compared to the CBF maps. The mean vowel and consonant identification scores in quiet and in noise were significantly higher in ABF than in CBF (p < 0.05) with a large effect size and the trend of improvement was seen with time. Voiced consonants had better scores than the voiceless consonants. Conclusion: The results demonstrated improved perception of vowels and consonants, particularly for sounds containing voicing cues after using the ABF maps. The results also suggested that ABF could be more effective for voice detection in noise. Overall, the findings indicate that correcting place mismatch with an ABF map may improve speech perception, at least among experienced adult CI users. Plain Language Summary: The goal of this experimental, long-term study is to evaluate speech perception over 6 months of the use of anatomy-based fitting (ABF), a relatively novel programming technique. While normal fitting uses the manufacturer's default frequency distribution algorithm, ABF programming in cochlear implant (CI) processors uses the position of the intracochlear electrode to disperse the associated frequencies. This indicates that the frequency properties of the nerves being stimulated by the electrode contact point match the frequency distribution caused by ABF. Consequently, it is hypothesized that ABF enhances auditory perception by improving place-pitch cue precision. Nine CI ears from eight experienced adult CI users were included in this investigation. Postoperative computed tomography scans were used in a surgical planning software called Otoplan to detect the locations of the implanted electrodes and corresponding center frequencies. To create the anatomy-based frequency bands, data from Otoplan were transferred into the Maestro 9.0 CI fitting program. Nonsense syllables with consonant-vowel-consonant (CVC) identification scores in quiet and in noise (+5 dB SNR) were compared in the beginning, 3, and 6 months after ABF use. The findings showed that vowels and consonants were perceived more clearly with the ABF map, particularly for sounds that had voicing signals. The outcomes also suggested that ABF would be more advantageous for speech recognition in the presence of noise. Overall, the findings imply that, at least for experienced adult CI users, treating place mismatch with an ABF map could enhance speech perception. [ABSTRACT FROM AUTHOR]