One of the most striking differences between Northern Khmer and the Khmer spoken in Cambodia is the way the final ‘ro’ is pronounced. It is written at the end of many Khmer words but is silent in Cambodian Khmer. However, in Northern Khmer it is not only pronounced, it is very strongly rolled. For example, the word “to ask” is not “sua” but “suarrrr.” Northern Khmer also incorporates many Thai words, and none of the French or English that has seeped into Khmer spoken in Cambodia.
(Frank Smith, Khmer language teacher, University of Wisconsin, U.S.)