As most already know Thai is a tonal language. English has 2 vowel sounds, short and long, excluding diphthongs. A diphthong is a single syllable word with 2 tones. Thai has 5 sounds for each vowel. They are normal, high, low, raising (like the end of a question) and falling. The diphthong "fire" is pronounced with a falling tone. If you get the tone wrong in Thai you may have a different word.