Feature analysis of segmental errors in children with phonological disorders

There has been a longstanding controversy about the existence, nature, and differentiation of developmental apraxia of speech (DAS), leading to numero us investigations of characteristics that define this articulatory disorder . An analysis of substitutions relative to target sounds led Thoonen, Maass en, Gabreels, and Schreuder (1994) to conclude that children with DAS show a pattern of feature retention in their error productions that contrasted w ith that of children with normal articulation. This pattern, in which place of articulation was retained in the substituted sound less frequently than manner of production or voicing, was considered by Thoonen et or, to be of diagnostic significance. The current research re-examines this claim by co mparing the retention patterns obtained by Thoonen et al. For children susp ected of having DAS to patterns for children suspected of having a phonolog ical disorder. An examination of substitutions used by 20 children who were diagnosed with and treated for phonological disorders demonstrated the sam e pattern of feature retention that was described for children with DAS. Th e results of this study showed that voicing is maintained most frequently; manner of production is the next most retained Feature; and place of articu lation is the feature that is retained least often when a substitute is use d for a sound that isn't produced correctly. In a second analysis, this pat tern of feature retention was compared to children's phonological knowledge as indexed by percent correct underlying representation (PCUR). Contrary t o the findings of Thoonen et al., however, the present work found an invers e relationship between retention of place and phonological knowledge. Child ren with greater phonological knowledge retained place less often than chil dren with more limited phonetic inventories. These patterns of feature rete ntion may be representative of specific development sequences that occur du ring phonological acquisition.