Non-tonal L2 proficiency facilitates the perception of tone and pitch contrasts in a tonal L1: evidence from Mandarin–English bilinguals

This study investigated how proficiency in a non-tonal L2 influences the perception of tone-related information in a tonal L1 among Mandarin–English bilinguals who are dominant in Mandarin. In Experiment 1, 65 participants with varying L2 proficiency completed a Mandarin tone perception task involving acoustically similar (T2-T3) and dissimilar (T1-T3 and T2-T4) tone pairs. In Experiment 2, the participants judged pitch height changes in T1, T2, T3, and T4. Results showed that bilinguals with higher L2 proficiency were more sensitive to the T2-T4 contrast and pitch height variations in T1, T2, and T3 than those with lower L2 proficiency. These findings suggest that increased proficiency in a non-tonal L2 selectively and positively influences the perception of tone pairs and pitch contrasts in a tonal L1, and that the effect may occur for the phonological/acoustic features common to English and Mandarin, extending the multi-competence theory to tone-related processing in bilinguals.