Thai leading letters and consonant clusters

A silent letter can affect the tone

In a leading-letter pattern, a written letter can guide the tone without adding a sound.

In หมา, the initial sound is /m/, not /h/ plus /m/. The silent leading ห makes the syllable follow high-class tone rules. With no tone mark and a live ending, this gives a rising tone. Compare the ordinary low-class start in มา, which has a mid tone.

Silent leading ห is used with these low-class sonorant letters: ง ญ น ม ย ร ล ว. Examples include หนู, หมวก, ใหม่ and แหวน. Check the vowel, ending and tone mark as well; leading ห does not make every word rising.

The familiar words อย่า, อยู่ and อยาก have a silent leading อ before ย. Add อย่าง, kind or manner. These four conventional words use this special middle-class reading pattern and have a low tone. Do not invent the same pattern for every written อ.

Keep both letters when you write. The leading letter still helps show the tone, even when you do not pronounce it.

Class, ending and marks work together; one silent leading letter is not a complete tone rule.

Two sounds or an extra syllable

A true cluster keeps both initial consonant sounds in one syllable.

In the standard careful reading of ปลา, the /p/ and /l/ come before the same vowel. There is no extra vowel between them. Familiar ครู similarly starts with /kʰr/. In regular true clusters, use the first written consonant’s class for the tone rule.

Compare ตลาด, the familiar word for market. It has a short linking /a/ before the stressed last syllable, not a true /tl/ start. In this word, the leading middle-class ต also controls the last syllable’s low tone. Not every adjacent pair behaves the same way.

In conversation, some speakers simplify /r/ or /l/ in a cluster. Learn the careful standard form so you can recognise the word across styles. This does not mean that every written pair is a true cluster or that every conversational reduction is a spelling mistake.

A written tone mark sits over the second consonant of a true initial cluster, but the first consonant still supplies the class. Word-specific exceptions and some borrowed spellings need a dictionary or a checked recording; this short rule is not a universal decoder.

The written class and the position of a tone mark are different things.

Keep silent letters in the spelling

A silent sign or group remains part of the written word.

The sign ◌์ marks a silent letter or group; the dotted circle here is only a display aid. In โทรศัพท์, the last written ท is silent and the spoken ending is /p/. In จันทร์, the group ทร์ is silent; the word ends in /n/. The sign is not a tone mark.

Some familiar spellings have a silent letter without this sign. In จริง, ร is silent in the standard reading, which starts with /t͡ɕ/. In ทราย, the written ทร is pronounced /s/ in the standard word for sand; the word has a mid tone. Do not change its class to high merely because you hear /s/.

Keep the complete spelling when typing these words. A silent letter can preserve a word’s history or spelling convention. The remaining sounds still determine whether the spoken syllable has a live or dead ending.

Do not assume that every word containing the same two letters has the same exceptional reading. Learn the checked whole word. Other silent groups and common special spellings are revisited when their vocabulary appears.

A silent written letter is still required for correct spelling.

Written letters and spoken sounds differ

In หมา, a silent letter affects the tone. In ปลา, two consonants are both heard before one vowel. In จันทร์, a silent group remains in the spelling. Counting written consonants is therefore not the same as counting spoken sounds or syllables.