The Effect of Between-Ear Speech Perception Asymmetry on Localization, Spoken Language, and Literacy for Adolescents With Cochlear Implants

Purpose: This study aimed to examine the effects of between-ear speech perception asymmetry on localization, spoken language, and reading in adolescents with early cochlear implants (CIs). Method: Eighty adolescents, who have long-term bilateral device use, participated: 10 with bimodal (BM) devices (CI plus hearing aid at the nonimplanted ear) and 70 with bilateral CIs (BCIs; 14 simultaneous, 56 sequential). Participants completed localization, unilateral speech perception, receptive language, and reading tests. Principal component analysis created composite scores for better-ear speech perception and between-ear speech perception asymmetry. Hierarchical regression examined the effects of demographics, audiological factors, and asymmetry on outcomes. Results: Localization scores for the two BCI groups did not differ significantly. Both BCI groups' localization scores were, however, significantly better than those of the BM group. Language and reading scores were not significantly different for the three groups. Regression analyses of localization scores revealed positive effects for earlier receipt of CI/s and negative effects of longer duration of acoustic experience, although this effect was moderated by degree of residual hearing. Larger speech perception asymmetry negatively affected localization scores but had no effect on language or reading scores. Conclusions: Speech perception asymmetry negatively affected localization but not language or reading in adolescent CI users. Prolonged acoustic experience (via BM use) increased speech perception asymmetry and reduced localization skills. Localization skills had no significant effects on spoken language or reading scores in adolescence. Clinically, asymmetry guides device recommendations, but asymmetry's impact, if any, differs by outcome. For children with better residual hearing, early acoustic hearing (via BM use) benefits both localization and language. Thus, careful timing of BCIs is advised. Supplemental Material: https://doi.org/10.23641/asha.33490615