#2 of forty-four · high class
ข
kho khai
ข ไข่ · egg
High class อักษรสูง
High class + no mark on a live syllable = rising tone; it reaches tones the low twins can't.

A consonant’s class exists for one reason: it decides the tone. High class + no mark on a live syllable = rising tone; it reaches tones the low twins can't. Here’s every outcome for ข as the initial:
| Syllable | – No mark | ◌่ mái èek | ◌้ mái thoo |
|---|---|---|---|
| Liveopen or sonorant end | rising | low | falling |
| Deadstop end or short vowel | low | low | — |
Live syllable — open or sonorant end
Dead syllable — stop end or short vowel
Change the initial to another class and the same marks produce different tones — that shift is what makes tone a small system, not 44 separate facts. Derive tones on the Tones surface →
Looks like — watch the shape
The tell: ข has a small head-loop at the top-left; ช drops the loop and rises to a sharper point.ข is /kʰ/ high · ช is /tɕʰ/ low.
Sounds like — watch the spelling
Same initial /kʰ/:
Same final /k/ — identical at a word’s end:
Start at the head — the little loop — then one continuous stroke. Written between the guide lines, the body sits in the middle band.
Indic — Sanskrit aspirate kh.