In these notes I compare three transcription systems, that developed by Mary Haas in the 1940s, that developed by (I presume) J. Marvin Brown for AUA in the 60s, and the more recent Paiboon scheme. Sources are Haas (1964), Brown (1969) and Becker (2002) respectively. There are many similarities between these systems; here I focus primarily on the differences.

Initial consonants

The following are the three systems’ transcriptions of the unaspirated/aspirated consonant pairs:

Thai Haas AUA Paiboon
ก-, ข- k-, kh- k-, kh- g-, k-
ต-, ท- t-, th- t-, th- dt-, t-
ป- พ- p-, ph- p-, ph- bp-, p-

Haas and AUA have a regular pattern, with the aspirated consonant being the same as the unaspirated one, plus h. The Paiboon system breaks this association with an informal choice of transcription.

Thai Haas AUA Paiboon
ย- j- y- y-
ง- ŋ- ŋ- ng-

Hass, influenced by IPA, uses j for the English y sound, whilst AUA use the more familiar (for English speakers), y.

Haas and AUA use the IPA ŋ for , whilst Paiboon uses the English-style ng.

Final consonants

Thai Haas AUA Paiboon
-ก -g -k -k
-ด -d -t -t
-บ -b -p -p

For final consonants, Haas uses -g/-d/-b, which better reflects the Thai spelling. AUA and Paiboon use -k/-t/-p.

Thai Haas AUA Paiboon
-ว -w -w -o
-ย -j -y -i

Haas and AUA use the same transcription for and sounds in both initial and final position. Paiboon (for some inexplicable reason) uses w- and y- for initial position and -o and -i for final position.


Thai Haas AUA Paiboon
◌ึ y ʉ ʉ
ไ◌ -aj -ay -ai

Haas uses y to represent the sound of ◌ึ whilst AUA and Paiboon use ʉ. With the diphthong , as might be expected, Haas uses j for the final sound, AUA uses y, and Paiboon sticks with i.

Vowel Length

In all three systems a long vowel is represented by the short equivalent repeated, e.g. a aa, i ii.


All three systems use the same set of diacritics to indicate tone (with no diacritic for mid-tone).

Syllable boundaries

Consider, for example, the following words:

Thai Haas AUA Paiboon
ริบหรี่ ríbrìi ríprìi ríp-rìi
ฝึกหัด fyghàt fʉ̀khàt fʉ̀k-hàt
ลูกโลก lûuglôok lûuklôok lûuk-lôok
ชุบเลี้ยง chúblíaŋ chúplíaŋ chúp-líang

Haas’ use of -g/-b/-d for final consonants means that the transcription is unambiguous because there is no consonant cluster beginning with these characters in her transcription. Paiboon is forced to add a hyphen between syllables, whilst AUA remains ambiguous.


Only Haas indicates syllable stress using ՛ after the stressed syllable. For example ความโกรธ is transcribed as khwaamkròot՛

Glottal stop

Both Haas and AUA indicates glottal stops. For example, อ่าน is transcribed ʔàan, and เกาะ is kɔ̀ʔ. Paiboon doesn’t bother.


Mary Haas’ transcription system was the first systematic one. It’s influenced by IPA, but doesn’t slavishly follow it. For example, เงิน is transcribed in IPA as ŋɤn, but Haas uses ŋən; ดื่ม in IPA is dɯ̀ːm, but Haas uses dỳym. It has been suggested that her choices were partly made on aesthetic grounds. ดื่ม written as dɯ̀ɯm would be just plain ugly. She also doesn’t representation of aspiration with a superscript h. For example, in IPA ขั้ว is kʰûːa, but she has khûua. This potentially could cause problems identifying syllable boundaries were it not for her inspired choice to use -g/-b/-d for final consonants.

She also differs from IPA in putting the stress indicator at the end of the syllable, rather than the IPA-standard before. I can only speculate that this was another aesthetic decision: given that stress in Thai falls on the final syllable, she didn’t want to disrupt the shape of two syllable words with a stress marker in the middle.

Her transcription system undoubtedly meets the needs of learners of Thai, fully and accurately representing the sounds of the language, with the exception of a tiny number of loanwords and onomatopoeias with short diphthongs such as เปาะเปี๊ยะ (spring roll) and ผลัวะ (the sound of a rock thrown into a bush or a flock of birds flying from a thicket).

AUA makes a number of changes to Haas’ system:

  1. Replace final -g/-b/-d with -k/-p/-t.
  2. Replace y with ʉ
  3. Replace j with y

Replacing the finals is perhaps a retrogressive step if one considers that the regular Thai final consonants are -ก -บ -ด. (This is predicated upon the hope that the transcription scheme will ease the transition to using Thai script.) Furthermore, it introduces ambiguity (not present in Haas’ scheme) into where syllable breaks lie.

The use of ʉ over y makes sense (to me at least), because it looks weird to see in transcription - accents are for vowels, not consonants. ʉ suggests it’s a variant of u (just as ɛ and ə, from their form, suggest they are variants of e, and ɔ is a variant of o).

Whilst for non-English speakers j makes sense, as in the German jawohl and the Dutch bijna, y is undoubtedly more familiar for native English speakers.

Turning now to Paiboon, they have made additional changes to the AUA system:

  1. Changed the initial consonants from k-/kh-, t-/th- p-/ph- to g-/k-, dt-/t-, bp-/p-. This destroys the simple relationship between unaspirated/aspirated consonant pairs. It may also lead learners to conclude that is pronounced like a hard English g (as in gun or goose). However, they are not the same sound. dt and bp could perhaps be explained by saying that the Thai sounds are between English d and t and b and p.
  2. Paiboon’s replacing ŋ with ng serves no useful purpose.
  3. Transcribing as w when an initial consonant and o as a final one, and transcribing as y when an initial consonant and i as a final one when they are exactly the same sounds seems utterly pointless and irrational to me. It also adds an extra hurdle in moving to writing Thai.
  4. Not showing glottal stops makes the transcription incomplete. I return to this later.

All three transcription systems are capable of representing the sounds of Thai (with the exception of the glottal stop in Paiboon). However, there is the issue of how the transcription schemes are actually used in learning materials. In particular, do the transcriptions reflect actual, real world pronunciation? Consider the following two words:

Thai Haas AUA Paiboon
สบาย sabaaj՛ sabaay sà-baai
กระจก kracòk՛ kracòk grà-jòk

In the first word, the first syllable includes an unwritten a. In normal speech this is pronounced unstressed, mid tone, no glottal stop. This is correctly shown in the words of Haas and AUA, but is unnaturally shown has having a low tone (and presumably a glottal stop, though Paiboon doesn’t show this). Only in the most formal, dictation-style speech is this the pronunciation, and this is not what learners need to learn.

In the second word, the first syllable includes a written a, but it is unstressed. Whilst AUA doesn’t show the stress, it gets the tone and absence of a glottal stop. Paiboon is again incorrect.

(One might wonder why Paiboon gets this consistently wrong. I believe this is caused by two factors:

  1. There is no way of explicitly writing an unwritten a without implying a tone and glottal stop. So, for example, the RID gives the pronunciation of the first word as [สะบาย] which is misleading.
  2. The compiler of the Paiboon dictionary is apparently in thrall to the spelling/respelling of words, and is oblivious to the common pronunciation. This is a not uncommon phenomenon for native speakers. Wells (1996) wrote "English people beginning the study of phonetics sometimes imagine that words such as write and wrong begin with a w-sound. Or they may believe that know ends with one (but not no). They are so dazzled by their knowledge of the spelling that they hold quite mistaken views about pronunciation.")

Paiboon’s failure to take into account the effects of stress is also reflected in other two syllables words where the first syllable is unstressed. For example:

Thai Haas AUA Paiboon
น้ำแข็ง námkhɛ̌ŋ՛ námkhɛ̌ŋ náam-kɛ̌ng

Here, when น้ำ is unstressed, it has a short vowel, not the long vowel indicated by Paiboon.


Whilst both Haas and AUA transcription schemes are capable of representing the sounds of Thai accurately (with some very minor limitations), the Paiboon system does not, ignoring both stress and glottal stops. The Paiboon system also includes many questionable choices of consonant transcription and is in no way an improvement over either Haas or AUA.


Becker, B.P. (2002). Thai-English English-Thai Dictionary with transliteration (sic) for non-Thai speakers. Paiboon Publishing

Brown, M.J. (1969). A.U.A. Language Center Thai Course Book 3

Haas, M.R. (1964). Thai-English Student’s Dictionary. Stanford University Press, 1964

Wells, J. (1996). Why phonetic transcription is important. Journal of the Phonetic Society of Korea 31-32:239-242, December 1996.

Matisoff, J. A. (1997). Remembering Mary R. Haas’s Work on Thai. Anthropological Linguistics, 39(4):594–602