Vocal intensity control challenges in bilateral cochlear implant users

Abstract

Bilateral cochlear implantation offers benefits but poses challenges for vocal intensity control. This study explored how differences in loudness growth between ears contribute to poor vocal intensity control in BiCI users. Experiment 1 tested 13 BiCI users with sustained vowel vocalization using both cochlear implant devices together and each one separately to measure their ability to control long-term vocal intensity variation (vAm). To determine if deficits in vAm when using both ears reflected mismatched loudness growth across ears, Experiment 2 examined loudness growth from each ear for a subset of participants and Experiment 3 manipulated the loudness growth function of the processor to change the shape of loudness growth function while measuring vAm for a subset of participants. Experiment 1 showed decreased vocal intensity control with BiCI devices compared to unilateral CIs. Experiment 2 revealed different loudness growth perceptions between ears for most BiCI users, possibly explaining their poor vocal performance with both implants. Experiment 3 demonstrated that changing loudness growth functions of the processor altered the ability to control vAm, indicating that changes in loudness growth affect vAm. The results suggest unmatched loudness growth perception between ears likely contributes to poor vocal intensity control in BiCI users.