Infants undergo fundamental shifts in perception that are reported to be critical for language acquisition. In particular, infants' perception of native and non-native sounds begins to align with the properties of their native sound system. Thus far, empirical evidence for this transition--perceptual narrowing--has drawn from socio-economically…

Language experience shapes infants' abilities to process speech sounds, with universal phonetic discrimination abilities narrowing in the second half of the first year. Brain measures reveal a corresponding change in neural discrimination as the infant brain becomes selectively sensitive to its native language(s). Whether and how bilingual…