Which tones are hardest, why, and where to start.
Comparing Finnish (no tone-language background) and native Mandarin listeners on tone and duration categorization: Finns discriminated within-category pairs better, while native Mandarin listeners had the advantage only on across-category pairs. The study is perception-only and gives no production error direction.
Source: Language and Speech. DOI: 10.1177/00238309261425682
Group averages tell you where to look, not what you actually do. Two speakers of the same first language can differ a lot. The only way to know is to record yourself and compare.
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