A comparative study of the phonology of pre-school children with specific language impairment (SLI), language delay (LD) and normal acquisition.

The phonology of two groups of SLI (n = 5) and LD (n = 5) children was analysed at age 3 and compared with two control groups: an age control (n = 5) and a language level control (measured using the MLU-W) (n = 5). Children with SLI and LD showed a delay in the acquisition of segments, syllabic structures and word structures, and in the simplification processes, compared with their age control group. However, SLI children also displayed significant differences vis-à-vis their language level controls, mainly in early acquisitions: vowels, nasals and stops at the segmental level, and in CV structures at the syllabic level. There is also a simplification process that seems to be more prevalent in these children than in their language level controls, namely, the deletion of unstressed syllables, mainly initial ones. The results enable SLI to be distinguished from LD and suggest that the development of SLI phonology is deviant. This deviation is interpreted as being a plateau in early acquisitions when later acquisitions have already appeared. The results are considered in the light of Leonard's surface hypothesis and an exclusively linguistic cause for this disorder is ruled out.