Residual hearing and sound quality in cochlear implant patients

Abstract

Cochlear implantation (CI) improves speech perception in adults with hearing loss. However, patient-reported sound quality varies widely and correlates poorly with objective outcomes. The impact of residual acoustic hearing trajectories on subjective sound quality remains incompletely understood. In this prospective cross-sectional study, adult cochlear implant recipients ( n = 31) were stratified into three groups based on low-frequency hearing: no residual hearing at baseline, preserved residual hearing following CI, and loss of residual hearing post-operatively. Subjective outcomes were assessed using sound quality and hearing questionnaires, compared with objective speech perception measures. Group differences were evaluated with covariate-adjusted analyses accounting for age, duration of deafness, and time since implantation. Overall satisfaction and functional hearing scores were similar between groups. However, patients who lost residual hearing demonstrated lower sound quality ratings compared to those without baseline residual hearing, with trend-level differences persisting after adjustment. Patients with preserved hearing did not demonstrate superior subjective speech perception despite comparable objective gains, suggesting a dissociation between measured performance and perceived benefit. Objective speech recognition improvements were similar across all groups and showed weak associations with patient-reported outcomes. Among patients with preserved hearing, those using electroacoustic stimulation demonstrated descriptively improved sound quality, though utilization was limited. In this exploratory, cross -sectional analysis of a small cohort, loss of residual hearing following CI may negatively affect perceived sound quality, while preservation alone does not guarantee improved subjective outcomes without optimized EAS integration. These findings support the importance of incorporating patient-reported measures alongside objective testing and suggest that underutilization of electroacoustic stimulation may represent a modifiable gap in care. Given the design and small sample size, results warrant confirmation in larger, prospective studies.