Neurodevelopmental changes occur with asymmetric hearing loss, limiting binaural/spatial hearing and putting children at risk for social and educational challenges. These deficits may be mitigated by providing bilateral hearing in children through auditory prostheses. Effects on speech perception and spatial hearing were measured in a large cohort of >450 children who were deaf and used bilateral cochlear implants or bimodal devices (one cochlear implant and a contralateral hearing aid). Results revealed an advantage of bilateral over unilateral device use but this advantage decreased as hearing in the two ears became increasingly asymmetric. Delayed implantation of an ear with severe to profound deafness allowed asymmetric hearing, creating aural preference for the better hearing ear. These findings indicate that bilateral input with the most appropriate device for each ear should be provided early and without delay during development.
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We would like to thank the Cochlear Implant Program audiologists (Patricia Di Santo, Susan Druker, Mary Lynn Feness, Gina Goulding, Laurie MacDonald, Rebecca Malcolmson, Valerie Simard and Vicky Papaioannou) for administering the tests during their clinical appointments. We gratefully acknowledge the time and help of the families and children who participated in this study. Funding was provided by: Canadian Institutes of Health Research (MOP-97924 to KAG, MFE1748241 to MJP), the Hospital for Sick Children (Restracomp and Clinician-Scientist Training awards to MJP), Ontario Ministry of Training (Graduate Scholarship to MJP), and the University of Toronto.
© 2018, The Author(s).