What is the primary reason infants can differentiate consonants in their native language?

Infants' ability to differentiate consonants in their native language primarily develops around 9 months of age. This is a crucial period in language acquisition, during which infants demonstrate a growing sensitivity to the phonetic contrasts of their language environment. Research indicates that by this age, infants have typically been exposed to the sounds of their native language long enough to begin recognizing and categorizing the distinct phonemes.

Around 6 months, infants are still generally able to distinguish consonants from a wider array of languages, reflecting a more universal ability to discern sounds. However, as they approach 9 months, they start to tune their perceptual abilities to the specific phonetic characteristics of their native language, leading to an improved capability to differentiate consonants that are particularly relevant to that language. This tuning process is influenced by the frequency of exposure to the sounds and patterns of their environment, which shapes their auditory discrimination abilities.

By 11-12 months, while infants may have even more refined skills, the primary shift in recognition and differentiation of consonants relevant to their native language typically occurs by around 9 months. This developmental milestone is significant, as it marks a transition from general sound discrimination to a more specialized understanding that aids in language learning and communication.