The audio is mostly from Modern Spoken Cambodian by Franklin E. Huffman, though there are some other sources thrown in. It would help you to buy/download the books for the practice exercises and substitution drills too.
I've replaced their pronunciations with an easy to read version. Consonant clusters are separated into syllables with a dot -- The word for 'I' being 'kuh·nyohm', and there is a Ъ symbol for the 'bp' sound, and a đ symbol for the 'dt' one.
Have fun.
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