Mandarin Chinese is a tonal language where variations in voice pitch distinguish word meaning. Acquiring tonal contrasts presents challenges for adult second-language learners. Undergraduates (N = 59) completed a computer-assisted language learning protocol, where they engaged in listening and repeating Chinese disyllabic nouns and matching them with corresponding pictures. Tone production accuracy was assessed at pretest/posttest using complexity invariant distance (CID), a quantitative metric of the distance between time series (learner vs. native-speaker productions). Word-level analyses found lower CID scores at posttest, indicating improvements in tone production after three blocks of word-picture matching. Fine-grained syllable-level analyses showed lower CID scores for first vs. second syllables, suggesting a primacy advantage. Accuracy on the Music Ear Test predicted lower CID scores, linking musicality with aptitude in learning tonal contrasts. No effects of nonverbal intelligence or language background were found. CID offers a robust method of assessing tone production accuracy for future studies.