Sounds of Vietnamese

Vietnamese (tiếng Việt) is in the Vietic subgroup of the Austroasiatic language family. Vietnamese is spoken as a first language by around 85 million people, mainly in Vietnam, where it is the official language. It has several times as many native speakers as all other Austroasiatic languages combined. 

This post covers:

• syllable structure
• word structure
• consonants
• vowels
• reduplication

Syllable structure

Vietnamese syllables have the following structure:

(C₁)(w)V₁(V₂)(C₂)

Each syllable:

• must contain a vowel (V₁)
• may start with an initial consonant (C₁)
• may have a labial sound ([w] – spelled <o> before [a, ă, e]; u> otherwise) before V₁, except after a labial consonant.  
• may end in a 2^nd vowel (V₂, forming a long vowel or a diphthong) or 2^nd consonant (C₂).
• carries a tone. Vietnamese has 6 (or perhaps 7 or 8) tones. For more on tone in Vietnamese and on the diacritics that Vietnamese spelling uses to write them, please see Some words distinguished only by tones – Language Miscellany

Word structure

Vietnamese is an isolating language, in which:

• each syllable usually has an independent meaning
• most disyllablic words can be viewed as combinations of monosyllables

Consonants

Table 1 shows the initial consonants (ones that may occur at the beginning of a syllable). Table 1 shows unvoiced consonants [f; t; s] before their unvoiced counterparts [v; d; z]. It shows the unaspirated consonant [t] before its aspirated counterpart [t^h].

Comments on table 1:

• Table 1 does not include the glottal stop [?]. Some people (eg Pham, 2006) say that all Vietnamese syllables begin with a consonant. They treat the glottal stop as a separate phoneme, analysing anh (‘elder brother’) as [ʔaɲ]. Other people (including Binh Ngo, 2021) view the glottal stop not as a separate phoneme but as the initial part of the allophone of a vowel not preceded by a consonant. They analyse anh as [aɲ].
• Some people identify an unaspirated, unaffricated palatal stop /c/, but others analyse this as an affricate /tc/, particularly in the speech of many younger speakers from Hanoi).
• Some people analyse the Hanoi Vietnamese finals written <-ch> and <-nh> as phonemes /c/ and /ɲ/. Other people treat those finals as allophones of the phonemes /k/ and /ŋ/, appearing after [i] and [e].

There are some regional variations:

• in the north, the sounds written <x> and <s> are both pronounced /s/, but in the south <s> is pronounced /ʂ/
• in the north, <ch> and <tr> are both pronounced /c/, but in the south /tr/ is pronounced /ʈ/.
• In the north, <r>, <d> and <gi> are all pronounced /z/. In the south, <r> is pronounced /r/ and <d> and <gi> are both pronounced /ʐ/.
• <v> is pronounced as /v/ in the north but as /j/ in the south.
• final <-nh> is pronounced as /-ɲ/ in the north but as /-n/ in the south. Final <-n> is pronounced as /-n/, but in the south is sometimes pronounced as /-ŋ/. Final <ng> is always pronounced as /-ŋ/.
• final <-ch> is pronounced as /-c/ in the north, but as /-t/ in the south. Final <-t> is pronounced as /t/, but in the south is sometimes pronounced as /-k/.

Whitman (2022) provides helpful charts of the Vietnamese consonants, showing both an IPA transcription and the normal Vietnamese spelling.

Final consonants

Only 6 consonants can occur at the end of a syllable: the unvoiced stops [p], [t], [k] and the nasals [n], [m], [ŋ].

The unvoiced bilabial [p] can only appear as a final and its voiced equivalent [b] can only appear as an initial consonant.

At the end of words, stops /p, t, k/ have no audible release ([p̚, t̚, k̚]).

When the velar consonants /k, ŋ/ follow the back rounded vowels /u, o, ɔ/, many speakers close their lips, producing [k͡p̚, ŋ͡m] or [k̚ʷ, ŋʷ].

Pham (2006) analyses in detail the differences between Hanoi (northern) Vietnamese and Saigon (southern) Vietnamese in the distribution of final stops and final nasals.

Vowels

Table 2 summarises the Vietnamese vowels. It shows the letter used for each vowel, followed by the sound (using symbols from the IPA, the International Phonetic Alphabet), enclosed in [square brackets]).

Vietnamese writing uses diacritic marks to distinguish pairs of vowels:

• a circumflex above the letters in <e> and <o> in < ê> and <ô> shows a vowel that is more closed (ie the tongue is higher) than in the vowels written with the unmodified symbols <e> and <o>.
• a hook attached to the right in the letters <ư> and <ơ> shows that the vowel is unrounded.
• a breve above the letter <a> in <ă> shows a vowel shorter than the vowel written as <a>.

There is a brief discussion of the distinction between rounded and unrounded Vietnamese vowels in Zsiga (2013), table 4.4, page 62, and in table 9.6 of Ladefoged and Maddieson (1996).

Table 2 uses the analysis in Nguyén (1990). This analysis mirrors the spelling, which uses the diacritic in <ư> and <ơ> consistently as simply an unrounded version of the sounds written as <u> and <o>.

Some of the other sources listed below differ from table 2 in some respects, for example by showing some or all of the following:

• some or all of [ɨ], [ɤ] [ʌ] and [aː] as central
• [ʌ] as a short (and central) version of [ɤ]
• [aː] as a long (and central) version of ă [ɐ].

Some descriptions mark more (or fewer) vowels explicitly as long (for example, using the diacritic <ː>). And some descriptions use some or all of the following IPA symbols:

• [ɯ] instead of [ɨ]
• [ɜː] or [əː] instead of [ɤː]
• [ɜ], [ə] or [ɤ] instead of [ʌ]
• [æ] instead of [a]
• [a] instead of [ɐ]

Whitman (2022) provides helpful charts of the Vietnamese vowels, showing both an IPA transcription and the normal Vietnamese spelling.

Final vowels

If a syllable ends in a 2^nd vowel, that vowel must be [i] after a back or central vowel or [u] after a front or central vowel. Some people analyse final [i] and [u] as semi-vowels or approximants [j] and [w], rather than as vowels.

Spelling final vowels:

• after a short vowel, [i] is written as <y> (eg cay ‘spicy’, cây ‘tree’).
• after [aː] and [ɛ], [u] is written as <o> (eg cao ‘tall’, deo ‘carry’).

Some spelling rules for vowels

• <y> replaces <i>:
  (a) when [i] is the only sound in a syllable (for example, in y [‘medicine’], y phúc [‘clothes’] or ỳ [‘idea, thought’]
  (b) in the diphthong [ie] when the syllable contains no initial consonant and does contain a final consonant (eg in yên ‘idea, thought’). This replacement is sometimes optional (eg bác sĩ / bác sỹ, ‘doctor’).
  (c) in a labialised syllable (eg khuy ‘button’)
  (d) optionally, in some labialised syllables starting with [ku] (eg quí / quý, ‘precious’)
• <a> replaces <e> before the finals:
  (a) [ŋ] when written as <-nh> (eg anh, elder brother’)
  (b) [k] when written as <-ch> (eg cách, ‘distant’)
• <a> replaces <ă> before a final semivowel <y> or <u> (eg máy, ‘machine’ and màu, ‘colour’).

Diphthongs

Vietnamese has 3 diphthongs: [ie]; [ɨɤ] and [uo], written in closed syllables (ones ending in a consonant) as <iê>, <ươ> and <uô > respectively. Each diphthong starts with a high vowel [i; ɨ; u] and ends with the corresponding close-mid vowel [e; ɤ; o].

In open syllables (ones ending in a vowel), the 3 diphthongs all end in a neutralised mid central vowel between [ɤ] and [ʌ], written as <a>: kìa [kìʌ]; cưa [kɨʌ]; cua [kuʌ].

In diphthongs, an initial [i] is written <y> in syllables with no initial consonant (eg yên, ‘peaceful’) and also in labialised syllables (eg khuya, ‘late night’; khuyên, ‘advise’).

Tone marks are placed above or below the 1^st vowel symbol in an open syllable (eg phía, ‘side’) but above or below the 2^nd vowel symbol in a closed syllable (eg phiến, ‘slat of wood’)

Reduplication

Vietnamese forms a large number of words by ‘reduplication’: a syllable is repeated, either before or after the base syllable. The repetition may be of:

• the whole syllable, unchanged (eg sáng sáng ‘every morning’, from sáng ‘morning’)
• the whole syllable, but with a different tone. The reduplicated syllable often precedes the base syllable (eg kha khá ‘rather good’ from khá ‘good).
• the whole syllable, but with a different tone and a different final consonant: [m; n, ŋ] instead of [p; t; k].  (eg đèm đẹp ‘rather beautiful’ from đẹp ‘beautiful’; tôn tốt ‘pretty good’ from tốt ‘good’; khang khách ‘somewhat different’ from khách ‘different’; nhinh nhích ‘move very slowly’ from nhích ‘move slowly’). The reduplicated syllable often precedes the base syllable.
• the initial consonant. The reduplicated syllable may follow the base syllable (máy móc ‘machinery’ from máy ‘machine’) or precede it (lung lay ‘be shaken’ from lay ‘shake’).
• the ‘rime’ (everything other than the initial consonant).  The reduplicated syllable may precede the base syllable (kheo léo ‘agile’ from khéo ‘skilful) or follow it (long vòng ‘move around’ from vòng ‘circle’).

Reduplication is also used in forming a few 3-syllable and 4-syllable words.

Sources

Illustration of the IPA, Vietnamese (Hanoi Vietnamese), James P Kirby, Journal of the International Phonetic Association, Volume 41 , Issue 3 (2011) ipa1100018a (cambridge.org)

Interactive IPA Chart: Vietnamese, Philip Neal Whitman (2022) https://ielp.ehe.osu.edu/files/2022/08/Vietnamese_IPA.pdf

Vietnamese, Đình-Hoá Nguyén, in The Major Languages of East and South-East Asia, Edited by Bernard Comrie Copyright 1990

Vietnamese; An Essential Grammar, Binh Ngo (2021)

Colloquial Vietnamese, Bac Hoai Tran, Ha Minh Nguyen, Tuan Duc Vuong, Que Vuong (2^nd edition, 2012)

Vietnamese Rhyme, Andrea Ho Pham (2006) https://www.academia.edu/34445567/Pham_2006_Vietnamese_Rhyme

Final consonants and glottalization: new perspectives from Hanoi Vietnamese, Alexis Michaud, Phonetica, 2004, 61(2-3) 10.1159/000082560. hal-00130119 https://hal.science/file/index/docid/130119/filename/michaud2004_glottalisation_Vietnamese_preprint.pdf

The Sounds of Language: an Introduction to Phonetics and Phonology, Elizabeth C Zsiga (2013).

The Sounds of the World’s Languages, Peter Ladefoged and Ian Maddieson (1996)