Cortical Systems that Process Language, as Revealed by Non-native Speech Sound Perception
Over the course of language acquisition, the brain becomes specialized in the perception of native language speech sounds, or phonemes. As a result, adult speakers are highly efficient at processing their native language but may struggle to perceive some non-native phonemes. This specialization is thought to arise from changes that occur in a person’s brain over the course of language acquisition. In this study adult native speakers of English were asked to discriminate between phonemes of varying degrees of difference from English: (similar-to-English: Tagalog /na/-/?a/; different-from-English: Ndebele /k||i/-/k!i/), as their brain activity was measured using fNIRS (functional near infrared spectroscopy) imaging. Left IFG showed activation only during the native condition; this finding is discussed in the context of neuroimaging work with infants and suggests that left inferior frontal region is critical for perceiving native phoneme contrasts during development and in adulthood.