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The aims of this study were to examine vocabulary scores of 5-year-old children who are deaf or hard of hearing (DHH), as well as the impact of early enrollment in specialized intervention on vocabulary outcomes. Receptive and expressive vocabulary scores were analyzed for 342 five-year-old children who are DHH enrolled in specialized listening and spoken language intervention programs. Regression analyses were utilized to examine the effects of age at enrollment on vocabulary outcomes. Overall, participants achieved scores within normal test limits on receptive and expressive measures of vocabulary. Children who enrolled in intervention prior to 28 months of age had better vocabulary skills at 5 years old. The findings support that children who are DHH can understand and produce vocabulary at skill levels commensurate with their typically hearing peers, regardless of severity of hearing loss. Results highlight the crucial impact of specialized programs on children’s lexical readiness to participate in general education settings by kindergarten.

A growing number of studies have shown a connection between rhythmic processing and language skill. It has been proposed that domain-general rhythm abilities might help children to tap into the rhythm of speech (prosody), cueing them to prosodic markers of grammatical (syntactic) information during language acquisition, thus underlying the observed correlations between rhythm and language. Working memory processes common to task demands for musical rhythm discrimination and spoken language paradigms are another possible source of individual variance observed in musical rhythm and language abilities. To investigate the nature of the relationship between musical rhythm and expressive grammar skills, we adopted an individual differences approach in N = 132 elementary school-aged children ages 5–7, with typical language development, and investigated prosodic perception and working memory skills as possible mediators. Aligning with the literature, musical rhythm was correlated with expressive grammar performance (r = 0.41, p p = 0.003), suggesting a privileged role of hierarchical processing shared between musical rhythm processing and children’s acquisition of complex syntactic structures. These relationships between rhythm and grammatical skills were not mediated by prosodic perception, working memory, or non-verbal IQ; instead, we uncovered a robust direct effect of musical rhythm perception on grammatical task performance. Future work should focus on possible biological endophenotypes and genetic influences underlying this relationship.