Mandarin tone learning in L2 adults: A test of perceptual and sensorimotor contributions

Adult second language learners (L2) of Mandarin have to acquire both new perceptual categories for discriminating and identifying lexical pitch variation and new sensorimotor skills to produce rapid tone changes. Perceptual learning was investigated using two perceptual tasks, musical tone discrimination and linguistic tone discrimination, which were administered to 10 naïve adults (native speakers of English with no tonal language exposure), 10 L2 adults, and 9 Mandarin-speaking adults. Changes in sensorimotor skills were examined with a pitch-shift paradigm that examines rapid responses to unexpected pitch perturbations in auditory feedback. Discrimination of musical tones was correlated significantly with discrimination of Mandarin tones, with the clearest advantage (better performance) among Mandarin speakers and some advantage among L2 learners. Group differences were found in the fundamental frequency (F0) contours of responses to pitch-shift stimuli. The F0 contours of Mandarin speakers were least affected quantitatively by the amplitude and direction of pitch perturbations, suggesting more stable internal tone models, while the F0 contours of naïve speakers and L2 learners were significantly altered by the perturbations. Discriminant analysis suggests that pitch-shift responses and tone discrimination predict class membership for the three groups. Discrimination of variations in tone appears to change early in L2 learning, possibly reflecting a process whereby new pitch representations are internalized. These findings indicate that tone discrimination and internal models for audio-vocal control are sensitive to language experience.