The aim of this study was to enhance our insight into the underlying deficit in developmental apraxia of speech (DAS). In particular, the involvement of planning and/or programming of speech movements in context was tested by analysing coarticulatory cohesion. For this purpose, second formant frequency measurements were conducted in repetitions of nonsense utterances ([[symbol: see text]] C = /s,x,b,d/; V = /i.a.u/), and compared across nine children with DAS, six normally speaking (NS) children and six adult women. The results showed both intra- and intersyllabic anticipatory coarticulation in NS children and adult women, in which the intersyllabic coarticulation was stronger in NS children than in adult women. The children with DAS showed more variability as compared to NS children, made, on average, less distinction between the vowels, and showed individually idiosyncratic coarticulation patterns. These results are discussed in the light of a delay as well as a deviance of speech development in children with DAS.

No abstract

Research in the field of speech production pathology is dominated by describing deficits in output. However, perceptual problems might underlie, precede, or interact with production disorders. The present study hypothesizes that the level of the production disorders is linked to level of perception disorders, thus lower-order production problems (such as childhood apraxia of speech; CAS) are linked to lower-order perception problems and higher-order production problems (phonological disorder; PD) are linked to higher-order perception problems. For this, various perception tasks were administered (non-word auditory discrimination task, word rhyming task, categorical classification, and discrimination task) in children with CAS, PD, or a mixture. The results show that children with PD only show higher-order perception problems, whereas children with CAS have difficulties on both lower- and higher-order perception tasks. In children with CAS, difficulties at lower-order processes might affect the higher-order processes in development. Furthermore, significant correlations were found between production and perception scores at different levels. Thus, a link between perception and production seems to be evident.

In this study the hypothesis of motor programming involvement in developmental apraxia of speech (DAS) was investigated by studying articulatory compensation. Five children with DAS and 5 normally speaking children (age 5;0 [years;months] to 6;10), and 6 adult women produced utterances in a normal speaking condition and in a bite-block condition in which the mandible was kept in a fixed position. Throughout the utterances, the course of the second formant was used to determine articulatory compensation and the effect of the bite block on anticipatory coarticulation. Results showed that the bite-block condition in normally speaking children, like in adult women, did not affect the extent of anticipatory coarticulation. In the speech of children with DAS, the bite block had large effects on coarticulatory patterns and on vowel quality, which, contrary to expectations, had improved. These results are interpreted as a clear demonstration of deficient motor programming in DAS.

These results suggest that CAS involves a symptom complex that not only comprises errors of sequencing speech movements but implicates comorbidity in nonverbal sequential functioning in most children with CAS.