Speech Perception in Infancy

Before they speak their first word, infants reach important milestones in their language development. In particular, their speech perception becomes attuned to the ambient language, first to its prosodic and then to its segmental properties. This article reviews developmental changes in speech perception across the first year of life. It begins with the earliest hearing experiences and then discusses how prenatal exposure shapes listening preferences in newborns, thereby providing a basis for further development. It furthermore sketches how infants attune their perception of sound contrasts to native phonological categories, both auditorily and audio-visually, at the cost of reduced sensitivity to nonnative contrasts. The second part of the article considers the factors that influence the infant's perceptual development, including quantitative and qualitative features of the language input and influences of emerging articulatory abilities. It further details different theories on the processes and mechanisms underlying perceptual attunement. It discusses how bottom-up and top-down information modulates learning, such as statistical and lexical cues to phonemic contrasts. The review concludes with an outline of how perceptual development in the first year of life links to further language development.