Tracking Acquisition of Language in Kids (TALK) study protocol: A longitudinal investigation of infants at high vs....

The sensitive period for phonetic learning, normally considered to be between 6-12 months of age, has been demonstrated as one of the earliest milestones for language development. Infant speech processing towards the end of the sensitive period has been shown to predict individual language development trajectories up to school entry and most recently, risk of speech and language disorders, suggesting its potential clinical relevance. Yet, this literature is largely limited to typically developing infants with regard to their family histories of speech and language delays or disorders. The current study begins to fill the gap by investigating associations between neural markers of the sensitive period, family history risk factors, and language outcomes by gathering extensive information from a large group of infants. Specifically, family information includes an extensive parental survey of family background and clinical history, a comprehensive assessment of language skills for one older sibling by a research speech-language pathologist (SLP), and a daylong audio recording in infants' homes for assessing their language environment. The study design focuses on comparing neural predictors of language development in infants with or without first-degree family history of speech and language delays and disorders (i.e., High vs. Low-Risk infants). Infants' neural speech processing is measured three times using Magnetoencephalography at 6 months, 12 months, and 14 months of age. Infants' language development is tracked until school entry by both parental surveys and the same comprehensive assessment protocol with a research SLP. This protocol documents the study design and methodological details for data collection and preprocessing. This study will allow our research team to start tackling important questions regarding early predictors of speech and language delays and disorders (e.g., late-talking, Developmental Language Disorder) and contribute significant value to the broader field.