Advancements in phonetics in the 21st century: Infant speech development

Abstract

Infant speech perception emerged as a field late in the 20th century. Early work focused on defining the initial state, and documenting the timecourse of changes in speech perception over the first year of life. At the turn of the century, attention shifted from studying when children became attuned to their native language, to asking how children achieved this transformation. Statistical learning became the dominant mechanism to explain language development. But, as researchers pushed the bounds of statistical learning, different questions took center stage: given the complexity of spoken language, how do infants determine which regularities to track? And are the patterns infants track influenced by their unique language learning environment? Inspired by these questions, researchers have shifted to studying acquisition across more diverse contexts, and to using dense corpora and big data approaches to examine how individual differences in children’s input relate to speech perception in the lab. In this paper, we first review this progression, summarizing how the field has arrived at the current state of the art. We then argue that the time is ripe for the development of new theoretical approaches, and sketch out the loose contours of SLED, a new 21st-century proposal that emphasizes the role of sociophonetic variation and the richness of the speech signal in early development. With advanced tools in hand and data from a wide variety of learning contexts increasingly available, we are excited to see how the field will evolve over the next 25 years.