Rhythmic Grouping in Developmental Language Disorder

Project Summary/Abstract Developmental language disorder (DLD) is classically identified by a morphosyntactic impairment, but the deficit profile incorporates other domains such as linguistic prosody and music. To date, the emphasis in the music domain has been on perceptual processing of rhythmic timing and musical sequences. However, production may also be implicated, since children with DLD have deficits in hierarchically organized prosody. In the proposed work, the aim is to use constructs from linguistic prosody to assess whether hierarchical processing drives the rhythmic deficits observed in the production of language and music. Importantly, language representations may also differ from music representations, specifically in that language conveys word and sentence content. Another gap that the present work will address is whether, because of its linguistic content, spoken prosody may be malleable or learnable in different ways than music. The significance of the planned research is to determine if a cross-domain rhythmic grouping deficit is present in school-aged children with DLD. In this planned study, 7- to 8-year-old children (Aim 1) will engage in a series of drumming and spoken language tasks involving rhythmic grouping abilities predicted to be shared across music and language (Aim 1). An additional linguistic task will be administered to test the malleability of prosodically vulnerable and stable forms in a referential as compared to a nonreferential condition (Aim 2). Key to the design of these studies is the inclusion of multiple levels of grouping structure, allowing for the analysis of hierarchical rhythmic organization in both music and language. Rhythmic performance will be assessed via both transcription (of beats and pauses in music, speech sounds and syllables in language) and movement implementation (motion tracking of hands in music, lips in prosody) metrics. Movement analyses allow for direct measurement of correlates of prosody, including relative and absolute amplitude and duration of syllables and beats. The goal of these studies is to determine if children with DLD show deficits in the implementation of rhythmically grouped, as opposed to ungrouped, elements and to what extent that implementation is influenced by lexical (referential) assignment. The findings from this project will have the long-term potential to provide new, domain general avenues for identification and intervention in DLD.