Bimodal stimulation in cochlear implant users: matrix test speech-in-noise performance and audiological characteristics

Abstract Background Unilateral cochlear implant (CI) recipients with contralateral moderate-to-profound hearing loss may either adopt a contralateral hearing aid (HA) or rely on CI-only listening. Bimodal stimulation (BS), combining electric and acoustic input, has been shown to improve speech perception in noise; however, some patients decline contralateral amplification despite residual hearing. Aims/Objectives This study aimed to characterize the audiological profiles of CI recipients who refuse contralateral HA use and to compare their speech-in-noise performance with that of BS users using the Italian Matrix Sentence Test. Material and Methods Unilateral CI users with contralateral moderate-to-profound sensorineural hearing loss were enrolled and divided into BS users and CI-only users. Pure-tone audiometry (PTA), word recognition score (WRS), and speech-in-noise performance were assessed. BS users were tested in both CI-only and CI+HA conditions. Results PTA and WRS in quiet did not differ significantly between groups (p = 0.12, p = 0.14, respectively). Within the BS group, speech-in-noise performance improved significantly with CI+HA compared with CI-only listening (p = 0.008). CI-only users showed slightly better residual contralateral hearing. Conclusion BS provides a significant within-subject benefit for speech perception in noise. Significance: Refusal of contralateral amplification may reflect an experience-driven perception of limited benefit, highlighting the importance of individualized counselling and outcome-based hearing device selection.