Korean Learners' Acquisition of Mandarin Disyllabic Tone Sequences Across Proficiency Levels

Background: Although tone acquisition is one of the most challenging aspects for adult second language (L2) learners, research remains limited on how learners from non-tonal first language (L1) backgrounds develop across proficiency levels. The current study examined Mandarin disyllabic tone sequences produced by learners at three proficiency levels. Methods: This study recorded the Mandarin tone production of beginner, intermediate, and advanced Korean learners and evaluated their accuracy and error patterns to determine whether similarities between L1 and L2 prosodic systems affect tone sequence difficulty. Results: Across groups, tone sequence rankings were consistent, differing mainly in accuracy rates. Learners showed an advantage in producing sequences aligned with Korean tonal patterns, such as T1-T1 and T3-T1, which were the easiest to produce. In contrast, sequences without Korean counterparts, particularly those ending in T2, remained the most difficult at all proficiency levels. Conclusions: Neurolinguistic evidence suggests that tones lacking L1 motor representations are disadvantaged by limited motor templates and weaker auditory coding, which together account for persistent difficulty with T2 sequences. Interestingly, T2 in word-initial position improved with experience, as increased exposure and practice helped learners form new sensorimotor routines supported by strengthened auditory-motor coupling. Over time, such experience-dependent neural reorganization enables more precise execution of rising F0 movements when tones occur at the beginning of a sequence, whereas carry-over interference from preceding tones continues to hinder accuracy in word-final position. This study provides insight into how sensorimotor and auditory systems interact in L2 tone learning, offering a neurocognitive framework for understanding prosodic transfer.