Extensive empirical research demonstrates that infants undergo perceptual narrowing during their first year of life, transitioning from universal phonetic discriminators to listeners whose speech perception is finely tuned to the contrasting sounds of their native language.
The retrieved literature robustly supports the claim that infants learn to distinguish different languages (or phonetic contrasts associated with them) during their first year of life, primarily through a process of perceptual narrowing and statistical learning (e.g., Papers 0, 2, 8, 9). None of the papers refute this foundational developmental milestone.