There are many systems for theromanization of theThai language, i.e. representing the language inLatin script. These include systems oftransliteration, andtranscription. The most seen system in public space isRoyal Thai General System of Transcription (RTGS)—the official scheme promulgated by theRoyal Thai Institute. It is based on spoken Thai, but disregards tone, vowel length and a few minor sound distinctions.
The international standardISO 11940 is a transliteration system, preserving all aspects of written Thai adding diacritics to the Roman letters. Its extensionISO 11940-2 defines a simplified transcription reflecting the spoken language. It is almost identical to RTGS. Libraries in English-speaking countries use theALA-LC Romanization.
In practice, often non-standard and inconsistent romanizations are used, especially for proper nouns and personal names. This is reflected, for example, in the nameSuvarnabhumi Airport, which is spelled based on direct transliteration of the name'sSanskrit root. Language learning books often use their own proprietary systems, none of which are used in Thai public space.
An international standard,ISO 11940, was devised with transliteration in academic context as one of its main goals.
It is based on Thai orthography, and defines a reversible transliteration by means of adding a host of diacritics to the Latin letters. The result bears little resemblance to the pronunciation of the words and is hardly ever seen in public space.
Some scholars use theCœdès system for Thai transliteration defined byGeorges Cœdès, in the version published by his student Uraisi Varasarin.[1] In this system, the same transliteration is proposed for Thai and Khmer whenever possible.
The Royal Thai System of Transcription, usually referred to as RTGS uses only unadorned Roman letters to reflect spoken Thai. It does not indicate tone and vowel length. Furthermore it mergesInternational Phonetic Alphabet (IPA) /o/ and /ɔ/ into⟨o⟩ and IPA /tɕ/ and /tɕʰ/ into⟨ch⟩. This system is widely used in Thailand, especially for road signs.
The ISO standard ISO 11940-2 defines a set of rules to transform the result of ISO 11940 into a simplified transcription. In the process, it rearranges the letters to correspond to Thai pronunciation, but it discards information about vowel length and syllable tone and the distinction between IPA /o/ and /ɔ/.
These are not reversible, as they do not indicate tone and underrepresent vowel quality and quantity. Graphemic distinctions between letters for Indic voiced, voiceless, and breathy-voiced consonants have also been neutralised.
In 1842, Mission Press in Bangkok published two pamphlets on transliteration: One for transcribing Greek and Hebrew names into Thai, and the other, "A plan for Romanising the Siamese Language". The principle underlying the transcription scheme was phonetic, i.e. it represented pronunciation, rather than etymology, but also maintained some of the features of Thai orthography.[2]
Several diacritics were used: Theacute accent was used to indicatelong vowels, where Thai script had two different vowel signs for the vowel sounds: อิ was transliterated asi, while อี was transliterated así. The exception to this rule was the signs for /ɯ/: อึ was transliterated asŭ, while อื was transliterated asü. The various signs for /ɤ/, were transliterated as ë. Thegrave accent was used to indicate other vowels: /ɔ/ was transliterated asò, while /ɛ/ becameè. ะ was transliterated with a hyphen, so that กะ becameka-, and แกะ becamekè-.Aspirated consonants were indicated by the use of anapostrophe: บb /b/, ปp /p/ and พp’ /pʰ/. This included separating the affricates จch /tɕ/ and ชch’ /tɕʰ/.
For many years, theSiam Society was discussing a uniform way in which to transliterate Thai usingLatin script. Numerous schemes were created by its individual members and published in its journal, including one tentative scheme by KingRama VI, published in 1913.[3] The same year, the society published a proposal for "transliterating Siamese words", which had been designed by several of its members working together. The system was dual, in that it separatedSanskrit andPali loans, which were to be transliterated according to theHunterian system, however, an exception was made for those words which had become so integrated into Thai that their Sanskrit and Pali roots had been forgotten. For proper Thai words, the system is somewhat similar to the present RTGS, for instance with regards to the differentiation of consonants' initial and final sounds. Some of the major differences are:
As the system was meant to provide an easy reference for the European who was not familiar with the Thai language, the system aimed at only using a single symbol to represent each distinct sound. Similarly, tones were not marked, as it was felt that the "learned speaker" would be so familiar with the Thai script, as to not need a transliteration scheme to find the proper pronunciation.[4]
KingVajiravudh, however, was not pleased with the system, contending that when different consonants were used in the final position, it was because they represented different sounds, such that a final -ล would, by aneducated speaker, be pronounced differently from a final -น. He also opposed using a phonetic Thai spelling forany word of Sanskrit or Pali origin, arguing that these should be transliterated in their Indic forms, so as to preserve their etymology. While most of Vajiravudh's criticisms focused on the needs and abilities oflearned readers, he argued against the use ofspiritus asper to indicate aspiration, as it would mean "absolutely nothing to the lay reader".[5]