Differential Impacts of Sentence Length on Speech Rate in Two Groups of Children With Neurodevelopmental Disorders

The primary purpose of this study was to examine the effect of sentence length on speech rate and its characteristics, articulation rate, and pauses in children with neurodevelopmental disorders.

Nine children diagnosed with cerebral palsy (CP) and seven children diagnosed with Down syndrome (DS) repeated sentences varying in length from two to seven words. Children were between the ages of 8 and 17 years. Dependent variables included speech rate, articulation rate, and proportion of time spent pausing.

For children with CP, there was a significant effect of sentence length for speech rate and articulation rate but not for the proportion of time spent pausing. In general, the longest sentences were produced with a faster speech and articulation rate than the shortest sentences. For children with DS, there was a significant effect of sentence length for the proportion of time spent pausing but not for speech rate or articulation rate. In general, children with DS spent significantly more time pausing in the longest sentences, particularly seven-word sentences, than in any other sentence length.

Primary findings include the following: (a) Articulation rate and pause time are differentially impacted by sentence length, and (b) children with CP and children with DS respond differently to increases in cognitive-linguistic load.