Speech Motor Processes in Developmental Apraxia of Speech Studied with EMMA
L Nijland, B Maassen, P van Lieshout
Studies on the underlying deficits in speech disorders in children are mainly based on acoustic measures. Acoustic studies on children with developmental apraxia of speech (DAS) suggest that these children produce incorrect realizations of correctly selected phonemes. By using the Electromagnetic Midsagittal Articulography (EMMA)-system direct measures of articulatory movements can be obtained. The EMMA-system provides a useful tool for distinguishing between phonological and motoric processes in children with DAS, in that articulatory gestures constitute the transition between abstract phonological characteristics and movements of the speech articulators.
Articulographic data were collected on the productions of three children with DAS and three normally speaking children. Earlier results showed specific deviant patterns in articulatory movements of children with DAS. Furthermore, normally speaking children showed more clear differentiation between movement patterns and movement stability depending on syllabic structure, as compared to the more variable and less distinct patterns produced by children with DAS.
More extensive qualitative analyses, presented in the present paper, suggest strong coarticulatory influences of the context on the articulatory gestures in normally speaking children, as is also found in acoustic measures, which do not seem to be present in the gestures of the children with DAS.