The following text is courtesy of http://www.tourismcambodia.com/Highlights/be4ugo/learnkhmer.asp
Here are some useful Khmer words and phrases, written phonetically, that will come in handy. Khmer may sound confusing. But with a little patience and practice, you can get by.
There are 33 consonants and 26 vowels. "Ai" is pronounced as in Thai; "ay" as in pay; "dt" takes the t sound while "bp" takes the p sound. "Oo" is pronounced as in cook and "ao" as in Laos.