Altered speech rhythm in children with developmental language disorder improved by rhythmic priming

Developmental Language Disorder (DLD) is characterized by impairments in speech comprehension and/or production that cannot be explained by hearing loss, intellectual deficits or neurological damage. While difficulties in phonology, semantic, and syntactic abilities have been extensively studied, prosodic aspects, in particular speech rhythm production, remain underexplored. For this aim, we analyzed spoken sentence productions of French-speaking children with and without DLD. Participants repeated sentences after having listened to either regular or irregular rhythmic primes. We examined (1) speech rhythm production, (2) the influence of rhythmic priming on speech production measures, and (3) the influence of covariates related to cognitive development on speech rhythm production and the rhythmic priming effect. Principal Component Analysis (PCA) was performed on twenty-four speech rhythm metrics, calculated from the duration of distinct linguistic units (i.e., vowels, consonants, syllables, words, pauses). PCA results showed that the dimensionality of speech rhythmic measures can be reduced to four main dimensions, regrouping speech rate, syllable variability, vocalic proportion and variability, and duration of pauses, respectively. The results showed that (1) children with DLD had slower speech rate and higher syllable variability compared to the control group, (2) exposure to regular rhythmic primes increased speech rate in children with DLD, whose rhythmic patterns became more similar to those of the control group, and (3) interindividual differences modulated speech rhythm patterns and effects of rhythmic priming. Our findings encourage the use of speech rhythm measures in the characterization of DLD, and the use of rhythmic stimulation in training and rehabilitation.