Lexical Tone Perception Ability of Profoundly Hearing-Impaired Children: Performance of Cochlear Implant and Hearing Aid Users

Objective: In tone languages such as Cantonese, a change in tone denotes a change in lexical meaning. The present study investigates the functional benefit of hearing devices in assisting tone perception among children with profound hearing impairment. Subjects: Fifty-two children with profound hearing loss were categorized into two groups based on their primary type of hearing device - a hearing aid group and cochlear implant group. Methods: A 75-item tone identification test covering all 15 Cantonese tone contrast pairs was administered to each subject under two conditions unaided (hearing devices turned off) and aided (devices turned on). The proportion of correct responses was computed as the total score for all items and subtotal contrast scores for each of the 15 tone contrasts. Results: The results indicated no significant differences between the children wearing hearing aids and those with cochlear implants under the unaided or the aided condition (z = 0.91, p = 0.36; z = -0.40, p = 0.69, respectively). Regardless of the type of device used, the total scores under the aided condition were higher than those under the unaided condition (z = -3.55 for the hearing aid group; z = -4.87 for the cochlear implant group, both ps <0.01). Conclusion: Children wearing hearing devices generally have a satisfactory functional gain in tone perception. No major observable difference was noted between children using cochlear implants and those using hearing aids. Tone contrast pairs with dissimilar fundamental frequency at onset and dissimilar tone contour patterns were more easily identified.