Which tones are hardest, why, and where to start.
Khmer is non-tonal. MA theses report a difficulty order of T2 > T3 > T1 > T4, with T2 most easily confused with T1; another reports T3 starting too high and merging with T2. Findings on f0 range contradict each other, so no direction is given here.
Source: 沈敏佳 (2018) 杭州师范大学硕论《母语环境下柬埔寨学生汉语单字调习得的实验研究》 | 尹健臻 (2021) 云南师范大学硕论 | 王娅玲 (2023) 兰州大学
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.
Take the free two-minute checkup →No signup, no download. Your audio is scored and discarded.