R Becomes H in Kham Mueang: Hak, Hon, Hu and Hundreds More

R becomes H is the most audible sound rule in Kham Mueang. Northerners say hak (รักฯ, read hak) where Central Thai has rak (love), hon for ron (hot), hu for ru (to know), and hao for rao (we). The rolled r that Central Thai still pronounces has turned into h in Kham Mueang, every time.

This post goes deeper than Kham Mueang sound rules. It shows how the dictionary writes the rule, how many words follow it, which words are exceptions, and whether sister languages such as Lao, Isan and Tai Lue have the same sound.

The rule as the dictionary writes it

The Moradok Lanna dictionary (in Thai) explains the rule under the letter ร (ra noi): ordinarily, in original Lanna or Northern Thai words, ร is pronounced ha. Its clearest example is the sentence "rao rak rong rian" (written form), which is spoken as "hao hak hong hian".

The dictionary also says some groups do not follow the rule: proper names, numbers, and words borrowed from other languages, which are usually pronounced with l instead. See "When R does not become H" below.

The letter r in the Lanna script: the letter h came later

In the Lanna (Tai Tham) script, native words such as hak, hon and hu are written with the letter r, the original form of the word, and then pronounced with an h. The Lanna script has a letter h too, but it came later.

The dictionary explains the letter h by citing a study by Kongkaew Veeraprajak and Niyada Tasukhon, which found the oldest evidence of this letter in 1592 CE and suggests it was created to write the sound /h/ directly. The reason: as more Pali words were borrowed, people tended to read the letter r in those words as l, and even in sermons the letter r was read as l, even for Lanna words. That caused confusion, so the letter h was needed to solve the problem.

On writing practice, the dictionary cites the Lanna–Thai dictionary (Mae Fah Luang edition) by Udom Rungruengsri (page 922), which holds that Lanna or original Tai words use the letter r and are always read as h, while the letter h is kept for borrowed words and imitated sounds.

Read about the whole script in What Is the Lanna Script?.

More than 400 entries in the dictionary

We counted from the Moradok Lanna dictionary itself (the Thai-form field of each entry, counted on 18 October 2026):

• 445 entries are read with an initial h.
• Of these, 401 entries have a Thai form starting with ร.
• Another 43 entries already have a Thai form starting with ฮ (see the exceptions below).
• From the other side, there are about 480 entries whose Thai form starts with ร, and 401 of them are read with h: more than 80 percent.

The count includes compounds (hak tae and hak paeng are separate entries, for example), so it is a rough picture, not a linguistic census. The examples below are grouped by theme, and every word is in the dictionary.

Everyday life: houses, tools and fields

Nature, animals and plants

Actions

People, numbers and welcome

Customs, traditions and sayings

Many of the words closest to Lanna life also have an h from an r.

Hit hoi will sound familiar because it is the word Northerners use for customs and traditions. Breaking a custom is called phit hit. The dictionary adds that failing to follow some customs is no wrong, but you might be criticised as uneducated or ill-mannered.

Read about the ceremony of hong khwan in Hong Khwan.

City names with an r in the middle

The rule applies to every r at the start of a syllable, not only at the start of the word. The name Chiang Hai (ชยฯงรายฯ, read jiang hai) is Chiang Rai, and it uses two rules at once: ch becomes j, and r becomes h. The full province names are in Lanna's Eight Provinces.

When R does not become H

The rule is strong, but it is not universal. Of the roughly 480 entries whose Thai form starts with ร, the other 79 split like this:

As the dictionary explains under the letter r, proper names, numbers and ranks, and loanwords are usually read with an l. Its examples are: the district Mae Rim is read Mae Lim, "roi tri Phrom" (Second Lieutenant Phrom) is read "loi ti Phom", "three thousand five hundred" is read "sam pan ha loi", and "America" is read "A-me-li-ka". The reading la is rarer, for example ra-khang (bell) is read la-kang and sa-ra-phi is read sa-ha-la-pi.

There is a lovely example of r becoming l in a year name. The dictionary records lao (เรั้า, read lao) as the Year of the Rooster, the tenth year of the zodiac cycle, whose symbol is the chicken. Anyone born in that year is a "pi lao" person.

An h that does not come from r

For another 43 entries, the h does not come from r. The dictionary gives several kinds of example.

• Words borrowed from other languages, such as huang sui (ฮวฯงซุ้, read huang sui, a Chinese grave, altered from huang chui), hang lo (ฮังฯโล, read hang lo, a small clay charcoal stove, which the dictionary says comes from ang lo) and hang le (ฮังฯเล, read hang le), the curry you can read about in Kaeng Hang Le.
• Words the dictionary links to h (ห), such as ha (ร่า, read ha), which the dictionary explains as ha, an epidemic disease of the old days, and the district name Hot (ฮอฯด, read hot), which the dictionary says was formerly Mueang Hot. (The other hot, meaning to arrive, is compared by the dictionary with rot, as told in Kham Mueang sound rules.)
• Imitated sounds and exclamations, such as hue, huet and hoe-hoe, which the Mae Fah Luang dictionary writes with the letter h.

The word hum (รุ่ม, read hum) means to simmer or boil over a low fire until tender and soft. It comes from rum by the rule, exactly as the examples above. Simmering pork until tender is the heart of kaeng hang le.

Sister languages: Lao, Isan and Tai Lue

The sound change from r to h is not found only in Kham Mueang. Researchers report it in several Tai languages. This is what we could check.

Lao. Garry W. Davis writes in his article on the Lao letter ຣ (r) (Journal of Lao Studies, 2015) that in early Lao r changed into h, for example rao to hao (we) and rak to hak (love), and that it happened in "closely related northern Thai varieties" too (citing Gedney 1966). Lao one-syllable words have h where Central Thai has r, such as hɔɔn, which matches ron (hot). Central Thai, Davis says, never underwent this change at all.

Davis adds that in words of two or more syllables the Lao r became l (for example lawaaŋ, "between"). That resembles the dictionary's note that loanwords and proper names are read with l and la in Kham Mueang. The Lao letter ຮ is also used only to write the h that came from r, which is close to what the dictionary says about the letter h in Lanna.

Isan. Atcharaporn Chansawang's article "Kham Mueang–Lao: Language and Culture as Siblings" (2011), which compares Northern Thai with Isan, concludes that both dialects say /h/ in place of /r/, and both lack the sound /ch/, using j or s instead. Both have six tones, and both have a soul-calling ceremony.

Tai Lue. The Wikipedia article on the Tai Lue language (which we use only as a lead) says that in many words the Thai r is h in Tai Lue, as in Lao and Tai Yuan, and gives ron, rak and ru as hɔ̀n, hak and hùː. The word "love" appears in the Dai Lue–English dictionary published on Webonary as hak, which agrees.

Why did r become h? Davis reports one explanation: the r of early Tai was probably trilled and strongly breathy. When the articulation weakened, it sounded close to h and merged with the h sound already there (citing Li 1977 and Court 1996). Linguists call this kind of change debuccalization, and it appears in other languages around the world.

Play: R becomes H

Test yourself on how many Kham Mueang words from r you know. The questions come from 25 real dictionary pairs, and after each answer you see the Lanna script and the dictionary meaning.

Summary

• Native words that start with r in Central Thai are read with h in Kham Mueang: hak, hon, hu, hao, hian, huean.
• In the Moradok Lanna dictionary, 401 entries out of about 480 whose Thai form starts with ร are read with h (counted on 18 October 2026).
• The exceptions are loanwords, proper names, and numbers or ranks, usually read l or la: Mae Lim, la-kang, and pi lao.
• Some Kham Mueang words with h do not come from r, such as huang sui, ha (epidemic) and the name Hot.
• Researchers find the same sound in Lao and Isan, and report it in Tai Lue.

Look up more Kham Mueang words that start with ฮ in the Moradok Lanna dictionary (in Thai). To learn the other rules read Kham Mueang sound rules, and to meet the other Tai peoples read Meet the Tai.

Sources

• The Moradok Lanna dictionary (moradoklanna.com/dict, in Thai): ฮัก · ฮ้อน · ฮู้ · ฮีตฮอย and the letter entries ร and ฮ, checked and counted 18 October 2026.
• Udom Rungruengsri. (2004). Lanna–Thai Dictionary, Mae Fah Luang edition (1st revised ed.). p. 922. (Cited in the Moradok Lanna dictionary, entry for the letter ฮ.)
• Davis, G. W. (2015). The Story of Lao r: Filling in the Gaps. Journal of Lao Studies, Special Issue 2, 97–109.
• Chansawang, A. (2011). Kham Mueang–Lao: Language and Culture as Siblings. Journal of Social Innovation and Lifelong Learning, 5(1). (In Thai.)
• Wikipedia. Tai Lue language (used only as a lead), and the Dai Lue–English Dictionary on Webonary.