Arts & Humanities Independent Learning Assignment Linguistics

Why have there been changes in the phonetics and phonology of Khmer since the existence of Proto-Austroasiatic?

This essay was written by upper-sixth former Tom Hemsworth, and shortlisted for the 2020 Independent Learning Assignment. The following provides a short abstract to the full essay.

Estimated read time of abstract: 4 minutes

Estimated read time of essay: 30 minutes

This essay was written by upper-sixth former Tom Hemsworth, and shortlisted for the 2020 Independent Learning Assignment. The following provides a short abstract to the full essay, which can be found at the bottom.

Estimated read time of abstract: 4 minutes
Estimated read time of essay: 30 minutes

Khmer is the language spoken mainly in the Kingdom of Cambodia, in South-East Asia. Khmer is part of the Austroasiatic language family, which encompasses 168 languages spoken across South-East Asia. The origin of this family is the language Proto-Austroasiatic which is believed to have originated in southern China. From this proto-language, several other language branches began to evolve from around 5000 BC. Modern Khmer is derived from the Khmeric branch, which appeared around 2000 BC. This too is a proto-language, called Proto-Khmeric. 

Around 600, the first stone inscriptions were recorded at the time that a group of kingdoms called the Chenla Empire occupied what is now Cambodia. This marked the birth of a new period in the Khmeric branch: Old Khmer. After the fall of the Khmer Empire in 1431, the language once again shifted to Middle Khmer, which spanned until around 1800, when Modern Khmer emerged. 

Upon examining the phonetics of Proto-Austroasiatic and Proto-Khmeric, I began to notice that there were not too many differences between them. This was surprising, as when you inspect the Swadesh 100 list, a list of one hundred basic words used for historical and comparative linguistics, the transition between the two columns is visibly the largest between any two consecutive word lists. The question is: why do the phonetics differ only slightly whereas the vocabulary is in many cases quite dissimilar? 

When reconstructing pAA, Paul Sidwell and Felix Rau used 21 consonants which were all carried through to pK. On the other hand, there are several vowel changes including the appearance of the long vowel sound [*ɛː], a particularly odd case. On the Swadesh list, most pK words in which [*ɛː] is present are unrelated to their pAA predecessors, which leads me to think that these are either new terms coined by people as they migrated from the Austroasiatic homeland in China into Cambodia and other South-East Asian countries, or if they are related, merely slight differences in pronunciation, such as between the pAA *cgəj and the pK *ckɛː (‘dog’). This point about migration brings me back to the question I posed. As Figure 1 indicates, when the Austroasiatic language family broke off into branches, its speakers either travelled west towards India or south into Cambodia and its neighbours. Many general terms will have only gone in one direction. Examples of this can particularly be found in words relating to flora and fauna. Take the pAA word *draŋ (‘horn’), which does not relate to the pK *sneːŋ. Words that derive from the pAA term can be found in Munda languages, for example dereŋ in Santali, spoken in Northeast India. 

Next in the timeline is the transition out of proto-language to Old Khmer. The basic consonant phonemes do not change from pK to OK; however, the voiceless stops [t], [p], [c] and [k] also began to occur with aspiration in OK, purely because it is a lot easier to say a word like *pkaːj with aspiration as pʰkaːj. As well as the phoneme [ɗ] and its bilabial equivalent [ɓ] appearing due to the glottis in the vocal cords being lowered and narrowed, vowel sounds became simpler in Angkorian society. The diphthong [*ie] evolved into [iə] or [iː] and [*uo] underwent similar alterations: either to [uə] or [uː]. 

However, there are certainly more apparent evolutions in language from OK to the modern day. Firstly, devoicing occurred. This is the term describing when the voiced stops in a language become voiceless. The reasons behind devoicing can be discovered by examining other languages in South-East Asia, such as the Tai family. The Chinese linguist Li Fang-Kuei wrote that “voiced consonants have become devoiced in practically all dialects” of Tai languages. Since the fall of Angkor was at the hands of the Ayutthaya, a kingdom which was located in modern day Thailand, I have deduced that the influence of this kingdom is a key reason behind devoicing. Devoicing did not occur in Thai until after the 15th century, so I believe that this process started thereafter and thus influenced the Khmer language.  

Another change was registrogenesis, the development of separate ways of speaking in a language. Two levels of lexical register occur in Khmer: ‘Head Register’ for formal language and ‘Chest Register’ for informal language. Chest Register, characterised by a breathier voice caused by the lower pitch from the larynx, was present in OK and MK. The low voice characteristic remains in standard Khmer, but it has lost its breathiness. 

Devoicing and the registrogenesis of Khmer are the reasons why, between OK and modern Khmer, new vowel sounds developed. For the first time, the vowels [ɨ], [ɨː], [ɑ], and [ɑː] appeared regularly in Khmer, as well as new short diphthongs. There are three of these: [ĕə], [ŏə] and [ŭə] (the diacritic ˘ represents an “extra-short” vowel). The open front unrounded vowel [a] is unable to be lowered any further therefore when people speak with a lower pitch, short diphthongs are born. 

During the French control of Cambodia, Khmer picked up loan words, which included new phonemes which had never been part of the language before, including [f] as in tiːfoŋ (‘typhoon’), and [z] as in zaːmaːʔiːk (‘Jamaican’). After the departure of the French, the future of Khmer looked set: the language was in the safe hands of Buddhist monks, including Chuon Nath, who compiled the first Khmer Dictionary. They removed many French and Siamese words from Khmer, a reason why French is no longer used as much in Cambodia. The Khmer Rouge halted this ‘Khmerisation’ process, particularly in education, which was greatly suppressed. Chuon Nath’s dictionary was only brought back in 2009, but at this point, Cambodian society had been partially taken over by English – virtually every sign in Cambodia now has both Khmer and English writing on it. 

The future may seem menacing for Khmer, but despite the worry of Khmer being dominated by English, I see no reason that it will disappear entirely. The influence of the modern, business- and technology-rich world will surely produce many new phonetical and phonological changes in the future, and it will undoubtedly prove to be a fascinating area of study. 

(Appendices showing timeline, phonemic inventories and Swadesh 100 list can be found in the full version of the ILA)  


pAA – Proto-Austroasiatic 

pK – Proto-Khmeric 

OK – Old Khmer 

MK – Middle Khmer 

To view Tom’s full article, follow this link below.


Diffloth, G., 2005. The Contribution of Linguistic Paleontology to the Homeland of Austro-Asiatic. In: L. Sagart, R. Blench & A. Sanchez-Mazas, eds. The Peopling of East Asia. Oxford: RoutledgeCurzon. 

Ray, N. & Lee, J., 2016. Cambodia. 10th ed. Singapore: Lonely Planet Publications Pty Ltd. 

Sidwell, P., 2018. Austroasiatic Studies. Hsinchu, National Tsing Hua University. 

Ferlus, M., 1992. Essai de phonétique historique du khmer. Mon-Khmer Studies, Volume 20. (French). 

Li, F.-K., 1977. A handbook of comparative Tai. Manoa: University Press of Hawaii. 

Shorto, H. L., 1962. A Dictionary of Modern Spoken Mon. London: Oxford University Press. 

Henderson, E. J., 1952. The Main Features of Cambodian Pronunciation. Bulletin of the School of Oriental and African Studies, 14(1). 

Wayland, R. P. & Jongman, A., 2002. Registrogenesis in Khmer: A phonetic account. The Mon-Khmer Studies Journal, Volume 32. 

International Phonetic Association, 1999. Handbook of the International Phonetic Association. 1st ed. Cambridge: Cambridge University Press. 

Sasagawa, H., 2015. The Establishment of the National Language in Twentieth-Century Cambodia: Debates on Orthography and Coinage. Southeast Asian Studies. 

Sok, K., 1999. La khmérisation de l’enseignement et l’indépendance culturelle au Cambodge. Bulletin de l’École française d’Extrême-Orient, Volume 86. 

SEAlang, n.d. Khmer Dictionary and Dictionary of Old Khmer[Online] 

Headley, R. K., 1998. Cham Evidence for Khmer Sound Changes. Papers in Southeast Asian Linguistics, Volume 15. 

Jenner, P. N., 1974. The Development of the Registers in Standard Khmer. South-east Asian Linguistic Studies, Volume 1. 

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