To determine the tone of any syllable the following four factors have to be considered.

1. Class of the initial consonant.

   The Thai consonants are divided up into three groups known respectively as HIGH, MIDDLE and LOW class consonants and the first thing to look at in determining the tone of a word or syllable is the class of the initial consonant.

   As has been mentioned before, there are many cases where the letter ห as an initial consonant is silent and there are a few cases where the letter อ as an initial consonant is also silent, but this makes no difference to the rule, the tone is still governed by the class of the initial consonant even though it be a silent consonant.

   The HIGH class consonants are;

   ข

   ฉ

   ฐ

   ถ

   ผ

   ฝ

   ศ

   ษ

   ส

   ห

   The MIDDLE class consonants are;

   ก

   จ

   ฎ

   ฏ

   ด

   ต

   บ

   ป

   อ

   All the remainder are LOW class consonants.

2. The final sounded consonant.

   All words which do not end in a vowel sound must have either M, N, NG, K, P, or T as the final sound.

   Note.
   Although this is strictly true, you will find that in conversation the final consonant is often slurred and particularly after a long vowel, the final P may sound more like a B and the final T more like a D.

   Where there is no tone mark, the tone of the syllable or word will depend on both the class of the initial consonant and on whether it ends with the M, N, NG sounds or the K, P, T sounds. It should be noted that a final consonant with the sign -์ (MY TUNTAKAHT) over it is not sounded and hence can have no effect on the tone.

3. The type of final vowel.

   If the word has no tone mark and ends in a final vowel, the tone is dependent on whether this final vowel is a long or short one.

   The short vowels for tonal purposes are -ะ, -ั, -ิ, -ึ, -ุ, the inherent “a”, the inherent “o” and all vowels shortened by the sign -็ over the consonant or by the addition of the vowel -ะ at the end.

   All the others are long vowels.

4. The tone mark.

   There are altogether four tone marks but only two namely (-่) MYAYK and (-้) MYTO are in common use.

   The other two (-๊) MYDTREE and (-๋) MYJUDTAWAH are used only in a few words beginning with middle class consonants.
   

Generated by Lyndon Hill on Thu Jul 20 18:40:32 BST 2006.

Copyright remains with the original authors.