Evaluation of an individual, anatomy-based fitting of the frequency allocation table in single-sided deaf CI patients

Introduction Cochlear implants (CIs) are usually fitted with the same mapping between electrode contacts and frequency bands for all patients, which can cause a, sometimes substantial, mismatch with the place frequencies of the electrode contacts. The study presented here is based on the hypothesis that CI patients benefit from a reduction of this “tonotopic mismatch” using an individualized image-based fitting of the frequency allocation table.

Methods The positions of the electrode contacts were identified in CBCT images of 12 single-sided deaf CI patients and the place frequencies were determined. The frequency allocation table was adjusted such that the mismatch between place frequencies and center frequencies was minimized. In phases of 4 weeks each following an A-B-A-B pattern, the standard fitting and the study fitting were used in turns.

Results Speech understanding was significantly better after fitting with the study fitting in 1 of 4 conditions. Changes in pitch perception during the study were individually different. After the second phase with the study fitting the subjective preference shifted noticeably towards the study fitting.

Discussion A phase of 4 weeks seems to be insufficient to show a strong effect of an individually adjusted fitting on speech understanding and pitch perception in experienced CI patients. However, since the subjective preference already shifted towards the study fitting during the course of the study, it is reasonable to assume that a similar fitting would show a stronger effect in newly implanted CI patients.

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Artikel online veröffentlicht:
12. Mai 2023