Language Learning in a Noisy World: A Systematic Review and an Exploratory Study

Language learning is an immersive experience that unfolds in an infant’s everyday environment. This environment is often noisy. Speech competes with television, music, household activity, overlapping voices, and other noises. These sounds can make speech more difficult to process and create more challenging conditions for communication and language learning. This thesis explored how children’s everyday auditory environments relate to language learning during the first three years of life. A systematic review first presented evidence from 24 studies examining infants’ everyday auditory environments and language development. It considered the sounds infants encounter, their associations with language and communication, and the processes through which competing sound may affect learning. Results found that infants spend substantial portions of their day in noisy environments. Television received the most research attention and was often linked to reduced caregiver speech, fewer caregiver–child interactions, and less favorable language-related outcomes. Experimental studies showed that background noise can interfere with neural speech encoding, speech perception, attention, and word learning. Music, appliances, and many other sounds commonly heard at home have received far less research attention. This was followed by an exploratory study which used daylong LENA recordings to examine how environmental sound and children’s vocalizations differed with age and across the day. Percentage noise changed little, whereas combined environmental sound and child vocalization counts increased across the 6–24-month age range and followed distinct daily patterns. Once age and clock hour were considered, children produced slightly less vocalizations during hours containing more combined environmental sound. The overall findings highlight the dynamic and multifaceted nature of infants’ auditory environments and suggest that their potential role in language development is only beginning to be uncovered.