Sixty prelingually deaf children were tested on Cantonese tone production ability at seven time intervals. Results of linear regression showed children in general improved in tone production performance over time. The magnitude of improvement, nevertheless, was different for children implanted at different ages. For children to acquire tone acquisition satisfactory, a critical age of four to receive implant is suggested. Optimally, children should receive their implant before two where they will be able to achieve around 80% accuracy in tone production within 1 yr of implant use. Children received their implant from two to just below 4 yr old achieved high tone production accuracy but needed a longer duration of implant experience. Children who received their implants at the age of 4 yr or older made little, if any, progress in producing tones correctly even after four to 5 yr of implant use.
Division of Otorhinolaryngology, Department of Surgery, The Chinese University of Hong Kong, Hong Kong, China.
Address for correspondence: Kathy Y. S. Lee, Assistant Professor, Department of Surgery, Prince of Wales Hospital, Shatin, N.T., Hong Kong.
Received February 16, 2006; accepted August 22, 2006.