Step 11: clusters and leading pairs

Two consonants together do one of three things, and telling them apart is the whole of this step. ONE: a TRUE CLUSTER (อักษรควบแท้), blended into a single sound. There are fifteen, and it is worth reading them as a list rather than a formula: กร กล กว, ขร ขล ขว, คร คล คว, ตร, ปร ปล, ผล, พร พล. Note that ผ blends only with ล, never with ร. Loanwords add a few more that behave identically: ฟร in ฟรี (free), บล in บล็อก, ดร in ดราม่า. The critical rule: the tone comes from the FIRST consonant of the cluster. ครับ blends ค and ร, and ค is LOW class on a dead short syllable, which is exactly why the particle you say all day is khráp on a high tone. TWO: a FALSE CLUSTER, pronounced as something else entirely. The one to know is ทร, which says s: ทราย is saai (sand), not thraai. THREE: a LEADING PAIR (อักษรนำ), where the consonants are NOT blended. The first takes an implicit short a and forms a small syllable of its own, and this is where the trap lives. THE TRAP: the leader lends its class forward ONLY when the second consonant is one of the ten low-class consonants that have no high-class partner: ง ญ ณ น ม ย ร ล ว ฬ. In that case the second syllable is toned as if it began with the leader's class. ขนม is khà-nǒm (ข lends high to น, so it rises), ตลาด is dtà-làat, and สวัสดี, the first word you ever learned, is ส lending high class to ว: sà-wàt-dii. Before ANY other consonant, no lending happens and the second syllable is toned from its own letter. สบาย is sà-baai, not sà-bǎai, because บ is middle class and keeps mid tone. สภาพ is sà-phâap, because ภ is a paired low-class letter and takes falling. Get this wrong and you mis-tone a large family of everyday words. HOW TO DECIDE, in order: 1. Does the second consonant simply close the syllable, with nothing of its own after it? Then it is a final, not a pair: read it with the implicit o from step 10 (คน, นก). 2. Is the pair one of the fifteen true clusters, with a vowel or final belonging to both? Blend it, tone from the first letter. 3. Is it ทร? It says s. 4. Does it start with ห or อ? That is step 9. 5. Otherwise it is a leading pair: insert a short a, and lend the class forward only if the second consonant is in ง ญ ณ น ม ย ร ล ว ฬ.