In my previous work as an environment advocate, I had the opportunity to visit schools in most Cambodian provinces. By doing so, I was able to practice my spoken Khmer which I studied for about a year. It wasn’t so easy but good thing we had an excellent teacher teaching Khmer for foreigners back then in the early 2000s at Institut Français Cambodge. And the more I visited local schools and talked to local people, the faster I became fluent in Khmer language.
In one of our visits, I saw these visuals pasted on a classroom wall.
These are the Khmer vowels, if I am not mistaken, and the sounds they correspond to and is illustrated by the schoolchildren. Visually, the Khmer script is almost similar to Thai and Laos.
Difficult to learn how to speak, you ask? Try reading and writing, lol.