Why One Symbol Makes Two Sounds

    Khmer vowels are dependent vowels: symbols that cannot stand alone and must attach to a consonant. Each dependent vowel has two possible readings, and the consonant it attaches to decides which one you use. If the consonant belongs to the ɔ-series, you read the vowel one way; if it belongs to the o-series, you read the same symbol another way.

That single rule is the reason Khmer looks unpredictable at first and becomes predictable fast once you know it.

The recommendation: Please define the series for consonant. For example: ក​ is ɔ-series when you combine with vowel ា​ it become a: ka:. The consonant គ work with the same vowel ា​​ it change sound to iə. it is kiə. 

Thank you/ អរគុណ