The perception of Cantonese lexical tones by early-deafened cochlear implantees

This study investigated whether cochlear implant users can identify Cantonese lexical tones, which differ primarily in their F0 pattern. Seventeen early-deafened deaf children $(\mathrm{age}\text{=4\hspace{0.17em}}\mathrm{years},$ 6 months to 8 years, 11 months; postoperative $\mathrm{period}\text{=11–41\hspace{0.17em}}\mathrm{months})$ took part in the study. Sixteen children were fitted with the Nucleus 24 cochlear implant system; one child was fitted with a Nucleus 22 implant. Participants completed a 2AFC picture identification task in which they identified one of the six contrastive Cantonese tones produced on the monosyllabic target word /ji/. Each target stimulus represented a concrete object and was presented within a carrier phrase in sentence-medial position. Group performance was significantly above chance for three contrasts. However, the cochlear implant listeners performed much worse than a $6\frac{1}{2}$ -year-old, moderately hearing impaired control listener who was tested on the same task. These findings suggest that this group of cochlear implant users had great difficulty in extracting the pitch information needed to accurately identify Cantonese lexical tones.