Measures of early phonetic development: A longitudinal analysis

Four measures were used to observe a hearing-impaired child's volubility, canonical babbling, consonantal development, and syllable complexity. Child A is a seriously hearing-impaired child identified early and provided with a cochlear implant at the age of 14 months. Child B with normal hearing was recruited for the same age range comparison. The recording place was in their homes and the natural interaction between caretakers and children was recorded. The data were collected at the age of 9-30 months. First fifty identifiable utterances in each session were selected for analysis. The indicated that 1) Two children had no significant difference in volubility at pre-linguistic stage. After 21 months, Child A produced more than Child B. 2) The onset of canonical babbling was at as early as 9 months of age in Child B, while Child A had the onset at the age of 18 months. From 27 months, Child A had similar amount of canonical babbling as Child B. 3) Child A had smaller consonantal variability than Child B. 4) Child B had a smooth and gradual growth from using simple syllable structures to more complex forms, whereas Child A showed unstable and sudden shift. These results indicated that Child A had approximately six months phonetic delay. Child B experienced rapid phonetic growth at 18 months, while Child A didn't show obvious growth until 27 months. Child A seemed to make up the delay and narrowed the gap with Child B after the cochlear implantation for one year.