The Thai language is spoken by 80% of the population in Thailand. There are about sixty other languages spoken which include: Mon, Khmer, Viet, Mlabri, Cham, Hmong, Karen, Akhan, and Moken. English is a mandatory school subject, however, fluency in English is rarely obtained.  Thai is considered an “uninflected, primarily monosyllabic, tonal language” belonging to the “Ka-Tai group”. It is said to have originated in the region between Vietnam and China and is related to languages spoken between Burma, Yunnan, Vietnam, and Laos. Thai written language was developed around 1283 and is based on Sanskrit, Pali, and Indian concepts. The Thai alphabet consists of fourty-four consonant graphemes and fifteen vowel graphemes.


Consonant Inventory

The Thai language consists of 16 basic consonant sounds represented in the IPA pulmonic chart. However, there are also aspirated voiceless stops for /p/, /t/, /k/, and an aspirated & unaspirated voiceless alveopalatal affricate. This reveals three patterns within the plosive manner: unvoiced-unaspirated, unvoiced-aspirated, voiced-unaspirated.

Vowel Inventory

There are nine basic vowels in the Thai language. Each vowel exists in long short pairs to become distinct phonemes. This can translate into semantic differences within the same vowel pronunciation (see Semantics section below). These basic vowels can be combined to form three diphthongs, and three triphthongs in the Thai language.


Unlike many Western languages, Thai grammar lacks definite structure. There are no verb conjugations, no noun declensions, no object pronouns, no articles. Context is often used instead of grammatical markers. Often times additional words are added to a sentence in order to clarify the meaning of a phrase.


The Thai language has no verb conjugations. Time words, instead are used to indicate the tense of the verb. This is comparable to placing the words, “will”, “now”, or “already” in front of or after a verb to express the time in which an action took place. For example, to express that an event or action took place in the past, a speaker may place “moer-warn-nee” which means “yesterday” after a verb. To say, “We learned Thai language yesterday” then a speaker would say, “rao rian par-sar Thai moer-warn-nee”. Translated word for word in English, this Thai phrase would be, “We learned language Thai yesterday”.


The following are translations of question words in the Thai language:
What? - “a-rai”
When? - “moer-rai”
Where? - “tee-nhai”
Why? - “tum-mai”

These question words are always found at the end of the sentence. Often times “yes” or “no” questions are asked by adding the word “mai” at the end of a sentence, which is similar to “no?” in English. When asking the question “When will you go home?” one would use the sentence, “You go home, when?”.


There is only one word to indicate possession in the Thai language. This word, “kong”, is placed in front of a noun or pronoun to indicate possession. However, this can also be omitted and instead the noun is simply placed in front of the noun which possesses it. For instance, in saying “Cherie's computer” one could instead say “computer Cherie” and the context and order of these words would indicate possession. In using the possessive word “kong” one could indicate possession by saying “computer kong Cherie”.


Most Thai words are monosyllabic. While syllables may have the same sounds, their meaning is dependent upon the tone at which they are uttered. There are five tones in the Thai language: Mid, low, falling, high, and rising. One may say the Thai word “mai” in five different tones, and the word will have five different meanings.

Vowel length is also phonemically distinctive in the Thai language. A word's meaning may depend upon the vowel's length. For example, when someone says the word, “khao” with a short vowel length, this word will mean “he” or “she”. When the same word is said with a long vowel length, it means “white”. The word meaning can also change when this is said in different tones as well.


There are four dialects within Thailand corresponding to the different geographic regions: Southern, Northern, Northeastern, and Central. Central Thai is considered the standard dialect of the Thai people.  In the Northeastern region of Isan, the primary dialect is of Lao origin and is considered a Lao dialect.
In addition to regional dialects, there are also four different languages in which Thai people speak based on social circumstance. Each of these social languages is used depending upon social ranking and by social situations by Thai royalty, religious figures, everyday polite interactions, and crude communications.

Written Language

The Thai alphabet consists of fourty-four consonant graphemes and fifteen vowel graphemes. When writing in Thai, the characters are placed from left to right with no spaces between words. There are separate graphemic representations based upon voiced, voiceless distinctions, and aspirated, unaspirated distinctions. Thus, for /t/ and /d/, there are 9 separate graphemes as shown in the chart below.

  Bilabial Labiodental Alveolar Post-alveolar Palatal Velar Glottal
Nasal /m/ ม   /n/ ณ,น     /ŋ/ ง  
Plosive /p/ ป; /pʰ/ ผ,พ,ภ; /b/ บ   /t/ ฏ,ต; /tʰ/* ฒ,ถ,ท,ธ; /d/ ฎ,ฑ*,ด     /k/ ก; /kʰ/ ข,ฃ,ค,ฅ,ฆ /ʔ/ อ* *

  /f/ ฝ,ฟ /s/ ซ,ศ,ษ,ส       /h/ ห,ฮ
Affricate       /ts̠/ จ; /ts̠ʰ/ ฉ,ช,ฌ      
/r/ ร

        /j/ ญ,ย /w/ ว  
Lateral Approximate     /l/ ล,ฬ        

* ฑ can be pronounced as [tʰ] or [d] depending on Thai words.
* * The glottal plosive is implied after a short vowel without a final consonant, or the silent อ before a vowel.

Implications for the SLP


The following link provides audio samples of different Thai speakers reading an English excerpt. This may be helpful to the SLP to distinguish common speech patterns that may occur in the English of some Thai speakers due to phonological differences: Speech Accent Archive-Thai

It has been noted that the Thai /r/ is a voiced alveolar trill or tap. This pronunciation sounds much like an English /l/. Thus, auditory discrimination between /r/ and /l/ may be difficult to distinguish between by some Thai speakers. For more regarding accent modification treatment of /r/ and /l/ please see Schmidt, A.M. & Beamer, J. (1998).

Because the /sh/ is not a phoneme in the Thai language, but the /ch/ is, auditory discrimination between these sounds may also pose difficulty for some Thai-English speakers.
Given that the Thai language has no inflection for nouns and no conjugation for verbs, it may be difficult for the Thai-English speaker to adopt these English rules. With this in mind, the lack of morphemic markers, plurality, and tense, may not necessarily indicate disorder in a native Thai speaker.


Original Contributors: Jacob J. Swain & Cherie M. Tanabe

References and Resources