Acoustic prominence: Understanding speech patterns in children with Down syndrome

Prominence in speech refers to the emphasis placed on certain words or syllables in English, making their salience through increased duration, increased intensity, and sometimes f0 dynamics. By marking acoustic prominence, speakers distinguish new from given information in speech. While a large body of relevant literature exists on how acoustic prominence is acoustically realized in typically developing (TD) children, little is known about how children with Down syndrome (DS) mark it. In this study, a "Puppet Show" task was conducted with 22 TD children and ten children with DS, one of whom was excluded because they were unable to produce the required target utterances despite multiple attempts, to compare the acoustic parameters used when distinguishing new and given information, focusing on mean f0, mean intensity, duration, and time-normalized f0. By using linear mixed-effects models and generalized additive mixed models, we demonstrated that children with DS have significantly higher overall mean f0 and lower intensity compared to TD children. The duration was not significantly different between the two groups. Our analysis further revealed distinct f0 contour patterns in the speech of DS children. While TD children exhibited clear rising and falling f0 contours to signal new and given information, DS children showed less controlled f0 contour patterns.