Tones! วรรณยุกต์

Tones in ไทย are not really difficult – not more than 中文, as far as I can tell. But the way they are represented in writing is… rather crazy.

From what I could understand so far:

1. each consonant has an inherent class: low, medium or high.
2. each syllable is either “dead” (ending either in a short vowel or in -p, -t or -k) or “live” (ending either in a long vowel or in a nasal).
3. the tone of each syllable depends on a combination of the consonant class, the syllable type and the vowel length.
   • for that effect, the consonant classes (low, medium, high) have no connection to the tone they indicate, i.e., a low class consonant in a dead syllable determines high tone with a short vowel and falling tone with a long vowel.
4. tones not possible by any of these combinations may be indicated by means of marks placed above the consonant.
   • two of these marks indicate different tones according to the class of the base consonant.
   • finally, there are two other marks for those tones not possible by any of the previously indicated means; these last and somewhat rare marks indicate the same tones regardless of any other factors.
5. for cases in which none of the previous factors would help, you can add a ghost consonant – usually the aspiration [h] or the glottal stop / silent consonant – before the main consonant, so that the tone will depend on the class of that ghost consonant instead of the main consonant.

Cool, eh? But it gets better. As you would expect, there are exceptions! They come in two flavours: circumstantial exceptions, i.e., syllables that change tone in predictable circumstances, usually an unstressed vowel turning to middle tone; and permanent exceptions, i.e., words regularly pronounced with a tone different from the one that is indicated by the spelling. :3

By the way, tones in ไทย are five: mid, low, falling, high, and rising, as indicated below.