Levels of complexity in phonological disorders: evidence from Cantonese.

Longitudinal data from ten phonologically disordered Cantonese-speaking boys were analysed for distinctive features (manner and place). The children labelled 95 pictures, attempting each initial Cantonese segment at least five times. The applicability of Dinnsen et al.'s implicational hierarchy to this data was examined. Categorization of each child's system according to an implicational hierarchy was successful for nine of the ten children when phonetic inventories were considered. In addition, a phonemic inventory based on Dinnsen et al.'s phonetic inventory captured the system of phonological contrasts used by eight of the ten children. The patterns of the children who did not match the hierarchy were considered deviant rather than delayed. The ability of the hierarchy to predict the route of development in this group of children was also examined. The hierarchies (both phonetic and phonemic) successfully predicted the route of change in these cases. Implications for the use of an implicational hierarchy in phonological assessment and treatment are discussed. Further research on feature-based phonological development, in both typically-developing and disordered phonological systems is required.