At birth, the baby brain can distinguish difference between all 800 sounds. That means that infants can learn any language to which they’re exposed. As time passes babies figure out which sounds they are hearing the most. Between six and 12 months, infants who grow up in monolingual households become attuned in the subset of sounds in their native language. By their first birthdays, monolingual infants begin to lose their ability to hear the differences between foreign language sounds.