Evaluating the Relationship Between Electrical Dynamic Range and Speech Perception Outcomes in Experienced Post-Lingually Deaf Adult Cochlear Implant Users: A Bicentric Study

TL;DR

This study explores how electrical dynamic range relates to speech perception in adult cochlear implant users, finding that speech therapy is linked to better outcomes.

Contribution

The study introduces speech audiogram curve morphology as a potential clinical tool for assessing cochlear implant performance.

Findings

Speech therapy significantly correlates with better speech recognition in cochlear implant users.

Speech audiogram curves show distinct morphologies based on performance levels.

EDR parameters were not independent predictors of speech recognition outcomes.

Abstract

Objectives: To analyze speech perception outcomes of a cohort of experienced adult cochlear implant (CI) users to explore whether there is a correlation with electrical dynamic range (EDR) parameters, and to describe speech intelligibility curve morphology according to the degree of CI performance. Methods: A bicentric retrospective observational study. Data were extracted from a cochlear implantation database from a total of 36 CI users implanted with Advanced Bionics devices. Results: Mean age at implantation was 56.61 years. In the majority of cases, hearing loss onset was more than 15 years before implantation (80.55%), and only 11.11% of cases preserved residual hearing. This resulted in a significant relationship between speech therapy and better speech recognition (p = 0.044). At the same time, no correlation was found between age, duration of deafness before implantation, and maximum speech perception achieved (p > 0.05). Mean speech audiometry curves displayed a roll-over phenomenon in poor performers and a plateau effect in average performers. In contrast, the mean curve of high performers exhibited a steeper morphology (p < 0.0001). Speech recognition threshold (SRT) and word recognition score (WRS) were predictors of speech audiogram curves (p = 0.006). No direct correlation was found between the mean T-level, M-level, dynamic range, and maximum recognition score, even after clustering electrodes by position along the cochlea (p > 0.05). Conclusions: EDR parameters did not emerge as independent predictors of speech recognition outcomes within this specific cohort. Speech therapy and rehabilitative efforts showed a significant relationship with improved performance, and speech audiogram curve morphology may offer a more specific clinical tool for assessing global CI performance. Further prospective studies with larger, more homogenous populations are required to validate these findings.

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