ห and อ Before a Low class consonant turns it into a high class

Words with more than one syllable will often have อะ as the unwritten vowel and the initial consonant will give its tonal quality to the following one Ex: ผนัง = Wall Because the word has more than 1 syllable, and there's no vowel written between ผ and น, we use อะ as the unwritten vowel. The tone for the first syllable ผะ is determined in a normal way (Low in this case), but because there is no written vowel between ผ and น, ผ will give its tonal quality to น. So น will act as a high class consonant and because ง is a live ending นัง will have a rising tone.

In general, for all clusters, the tone of the syllable is calculated based on the consonant class of the first consonant in the cluster; the tone marker (if any) is nevertheless placed above the second consonant in the group.