Effects of Face Masks on Word Learning in Preschool-Age Children

Project Summary Children's ability to understand and learn from spoken language declines when speech quality is low. This can be particularly problematic during the preschool years, a time when children's sole source of vocabulary is through spoken language and when children build foundational vocabulary knowledge that is essential for future reading and academic achievement. The use of face masks in educational settings, including preschools, to mitigate the spread of COVID-19 introduces a barrier to the high-fidelity speech input that children need. Specifically, face masks acoustically filter speech by limiting access to high frequency speech sounds necessary for accurate speech perception (e.g., the /ch/ and /s/ in the word "cheese"). Furthermore, some face masks limit access to visual speech cues. Although preschool children are frequently tasked with resolving degraded speech due to background noise in their naturalistic environments, their speech perception is less resilient than that of older children to these manipulations. A robust literature demonstrates that degraded speech both disrupts the recognition of spoken words as well as taxes cognitive processes, such as attention and working memory, that are fundamental to word learning. Thus, chronic exposure to talkers who use face masks may create a barrier to vocabulary development in preschool-age children, which may lead to negative downstream consequences on their future language development. The purpose of the present study is to test the effect of face masks on word learning in preschool-age children. We hypothesize that reduced access to the acoustic and visual components of speech due to mask use by the target talker will result in poorer word learning. To test this hypothesis, children between 4 and 6 years of age will be taught words across conditions that vary in both the acoustic fidelity of the speech signal (Aim 1.1) and access to visual speech cues based on mask use by a target talker (Aim 1.2). Although the availability of clear masks allows access to visual speech cues, they can cause greater acoustic filtering. To test the potential trade-off between acoustic fidelity and availability of visual speech cues, we will also test the effect of mask type (Aim 1.3): we will compare children's word learning between a disposable medical mask that has moderate acoustic filtering but limits access to visual speech cues and a ClearMask® that has significant acoustic filtering but provides access to visual speech cues. Finally, we will determine the extent to which individual factors, such as vocabulary size and verbal working memory skills, influence children's performance across these conditions (Aim 2). Through accomplishing these aims, we will determine how face masks affect word learning in preschool-age children and will identify which children are most at risk for poor vocabulary development when face masks are used. More broadly, the results will show how disrupted access to a high-fidelity speech signal alters children's ability to form new phonological representations. This work aligns with the research priorities of the Child Development and Behavior Branch of the NICHD because vocabulary development is critical to long-term language and academic development.