Chronic exposure to background noise during childhood negatively impacts language, literacy, and cognitive development, with repercussions for children?s academic achievement and future employment potential. A putative mechanism linking noise to decrements in language and cognitive development is that noise disrupts young children?s ability to build a vocabulary. A robust literature demonstrates that noise disrupts the perception of spoken words primarily through energetic masking, in which noise limits high fidelity encoding of target speech, and informational masking, in which noise taxes cognitive processes such as attentional control and working memory. Background noise likely disrupts word learning through similar mechanisms. Although there have been studies testing the effects of noise on word learning, these studies are few in number and variable in methodology. The noises in children?s naturalistic environments vary in type (e.g., environmental noise [air conditioners] and background speech), intensity level (i.e., how loud it is), semantic content (i.e., whether the child understands the background speech), and spatial location: factors that exert different amounts of energetic and informational masking. Additionally, differences in cognitive and language abilities among preschool-age children likely affect their susceptibility to the negative effects of noise. Thus, we lack knowledge about how cognitive factors interact with variations in noise to affect word learning in young children. This is a critical gap because spoken input is the sole source of word learning in prereaders and an important source of word learning over the lifespan. The present study will test the time course of novel word learning in the presence of background noise that varies in type, spatial location, semantic content, and intensity level, which are factors that influence young children?s perception of target speech. Specifically, the noise will vary by whether it contains speech content or not (Aim 1), whether it is co-located or spatially separated from the target speech (Aim 2), whether it contains familiar semantic and phonetic content versus only familiar phonetic content (Aim 3), and its intensity level (Aims 1, 3). To accomplish these aims, a large cohort of children between 4 and 6 years of age will be trained on novel word- referent pairs across three subsequent days. This age range is targeted because children?s speech perception is highly susceptible to the effects of noise during this time in development, and it is an important age to build foundational vocabulary skills. Each child will be tested in one noise condition, and the noise will be systematically changed across conditions. Through this approach, we will determine how various noise conditions affect both the number of words learned and the phonological precision of children?s representation of the words throughout the learning process. This work aligns with the research priorities of the Child Development and Behavior Branch of the NICHD as we will identify how aspects of children?s environments affect word learning, a critical process for long-term language, cognitive, and academic outcomes.
(Public Health Relevance) Children's naturalistic environments often contain background noise?such as other talkers, televisions and computers, heating and ventilation systems, and outside traffic?that interferes with children's ability to process spoken input. Spoken input is the sole source of word learning for preschool-age children; thus, background noise may interfere with children's ability to learn words, a critical process during early childhood that is related to long-term academic and occupational success. The purpose of the proposed research is to determine how different types and intensity levels of background noise disrupt word learning, which ultimately will advance our understanding of how to maximally support word learning in real-world environments.
