The acquisition of mandarin tonal processes by children with cochlear implants

Purpose: Children with cochlear implants (CIs) face challenges in acquiring tonal languages, as CIs do not efficiently code pitch information. Mandarin is a tonal language with lexical tones and tonal processes such as neutral tone and tone sandhi, exhibiting contextually conditioned tonal realizations. Previous studies suggest that early implantation and long CI experience facilitate the acquisition of lexical tones by children with CIs. However, there is lack of acoustic evidence on children’s tonal productions demonstrating that this is the case, and it is unclear whether and how children with CIs are able to acquire contextual tones. This study therefore examined the acoustic realization of both lexical tones and contextual tones as produced by children fitted with CIs, exploring the potential effects of age at implantation and length of CI experience on their acquisition of the Mandarin tonal system. Method: Seventy-two Mandarin-learning preschoolers with CIs, varying in age at implantation (13-42 months) and length of CI experience (2-49 months), and 44 normal hearing 3-year-old controls were recruited. Tonal productions were elicited from both groups using picture-naming tasks and acoustically compared. Results: Only the early implanted group (i.e., implanted before the age of 2 years) produced normal-like lexical tones and generally had contextual tones approximating those of the normal-hearing children. The other children, including those with longer CI experience, did not have typical tonal productions; their pitch patterns for lexical tones tended to be flatter, and contextual tone productions were unchanged across tonal contexts. Conclusion: Children with CIs face challenges in acquiring Mandarin tones, but early implantation may help them to develop normal-like lexical tone categories, which further facilitates their implementation of contextual tones.