The substitution of a click for sibilants: a case study.

In the case study presented in this paper a 4-year-old English-speaking girl showed an unusual phonological pattern of substituting a dental click for the sibilants /s, z, ∫, ℑ, t∫, dℑ/. After two intervention sessions this pattern was eliminated from her speech and all the sibilants were produced correctly. In addition to providing an example of a child's contrastive use of a non-English segment, this case study provides evidence of a child's selection of a sound substitute on the basis of its auditory rather than articulatory similarity to the target phonemes. The rapid rate of change observed in the child's phonological system seems consistent with a phonological learning model in which the child has adult-like underlying phonological representations.