The Challenges of Restoring Binaural Hearing: A Study of Binaural Fusion, Listening Effort, and Music Perception in Children using Bilateral Cochlear Implants

Benefits from bilateral implantation vary and are limited by mismatched devices, stimulation schemes, and abnormal development. We asked whether bilateral implant use promotes binaural fusion, reduces listening effort, or enhances music perception in children. Binaural fusion (perception of 1 vs. 2 sounds) was assessed behaviourally and reaction times and pupillary changes were recorded simultaneously to measure effort. The child's Montreal Battery of Evaluation of Amusia was modified and administered to evaluate music perception. Bilaterally implanted children heard a fused percept less frequently than normal hearing peers, possibly due to impaired cortical integration and device limitations, but fusion improved in children who were older and had less brainstem asymmetry and when there was a level difference. Poorer fusion was associated with increased effort, which may have resulted from diminished bottom-up processing. Children with bilateral implants perceived music as accurately as unilaterally implanted peers and improved performance with greater bilateral implant use.M.Sc