Using unilateral stimulation to create a reference for bilateral fusion judgments

Measuring binaural fusion can be challenging, especially with bilateral cochlear implant (CI) users. This study validated a technique of using unilateral stimulation to create a reference for measuring fusion. Seven bilateral CI users listened to stimuli randomly presented to the right, left, or both ears. Participants indicated the size, number, and location of the resulting image(s) they perceived. The participants had largely unitary, punctate percepts that were lateralized to the stimulated ear for unilateral stimuli. The image was centered but more diffuse when the stimuli were presented bilaterally. The results suggest unilateral stimuli can provide a reference for binaural fusion.