Language learning becomes increasingly difficult when novel linguistic features are introduced. Studies have shown that learners from various language backgrounds can be trained to perceive lexical tone, which assigns meaning to words using variations in pitch. In this thesis, we investigated whether native speakers of tonal Mandarin Chinese and tonal Vietnamese outperformed native speakers of nontonal English when learning Hakka Chinese tones following five sessions of tone training, and whether the complexity (i.e., density) of a listener’s native tone inventory facilitated nonnative tone learning. All groups improved in tone identification and tone word learning following training, with improvements persisting three weeks following the cessation of training. Although both tonal groups outperformed the English group in most tasks, the Mandarin group showed the most consistent advantages over the English group across tasks. Findings suggest that tone experience bolsters tone learning, but density of the tone inventory does not provide an advantage. Confusion patterns offer detailed insight of the interaction between nonnative tones and native tonal and intonational categories
