Mapping of prosodic structure onto words and phrases in children's and adults' speech production

Abstract

Direct recordings of lip and jaw movement were obtained to investigate how children and adults differentiate prosodic structure both within iambic and trochaic words and across word boundaries. It was hypothesised that children, especially those with less language skills, would be particularly likely to produce strong-weak (or trochaic) sequences. This experiment examined children's (both normally developing and specifically language impaired, aged 4–6 years) and adults’ productions of prosodic sequences that were controlled for syntactic and phonetic content, but that differed in rhythmic alternations, both within words (i. e., iambs vs. trochees) and across words (i. e., optimal strong-weak vs. stress gap or stress clash). To avoid final position effects, target words were in utterance internal position. Analyses included kinematic measures of prosodic structure (i. e., amplitude and duration of movements in weak vs. strong syllables; ratios of weak-to-strong movements). Consistent with prior work, weak syllables in iambs were produced differentially from those in trochees; though these effects were now observed in utterance position. However, in noun-noun sequences within a phrase, even when the rhythm rule was violated, prosodic foot structure was not reorganised as a function of rhythmic properties of the utterance. Overall, children with the least mature language skills demonstrated poor control of temporal and amplitude aspects of movement, especially in weak syllables. Findings are related to the organisation of speech production units across prosodic levels.