Final answer:
Babies recognize the sounds of their native language by differentiating between phonemes, a skill that becomes fine-tuned by around 1 year of age to focus on the specific sounds used in their environment. Their ability to distinguish these sounds is part of the broader language acquisition process that starts even before birth.
Step-by-step explanation:
Babies recognize key vowel and consonant sounds of their native language by distinguishing phonemic differences. Initially, infants can differentiate between the sounds of all human languages. However, by the time they are around 1 year old, their ability to discriminate is narrowed to the phonemes present in the languages of their environment. This phonemic recognition aligns with the concept of a critical period in language development, where the brain is exceptionally receptive to learning the sounds of its native language.
Language acquisition begins before birth, as babies are adept at recognizing their mother's voice and can distinguish between native and foreign languages. The gradual process of learning pinpoints specific milestones such as cooing, babbling, and eventually the 'one word' stage, highlighting the innate cognitive abilities that facilitate language learning from passive exposure to environmental talk.