Editing Vietnamese language (section)

==History==
Austroasiatic is believed to have dispersed around 2000 BC.{{sfn|Alves|2020|p=xviii}}
The arrival of the agricultural [[Phùng Nguyên culture]] in the [[Red River Delta]] at that time may correspond to the Vietic branch.{{sfn|Sidwell|Alves|2021|p=189}}

This ancestral Vietic was typologically very different from later Vietnamese.
As well as monosyllabic roots, it had [[sesquisyllabic]] roots consisting of a reduced syllable followed by a full syllable, and featured many consonant clusters.
Both of these features are found elsewhere in Austroasiatic and in modern conservative Vietic languages south of the Red River area.{{sfn|Alves|2021|p=661}}
The language was non-tonal, but featured glottal stop and voiceless fricative codas.{{sfn|Alves|2021|p=662}}

Borrowed vocabulary indicates early contact with speakers of [[Tai languages]] in the last millennium BC, which is consistent with genetic evidence from [[Dong Son culture]] sites.{{sfn|Sidwell|Alves|2021|p=189}}
Extensive contact with [[Chinese language|Chinese]] began from the [[Han dynasty]] (2nd century BC).{{sfn|Alves|2020|p=xix}}
At this time, Vietic groups began to expand south from the Red River Delta and into the adjacent uplands, possibly to escape Chinese encroachment.{{sfn|Sidwell|Alves|2021|p=189}}
The oldest layer of loans from Chinese into northern Vietic (which would become the Viet–Muong subbranch) date from this period.{{sfn|Alves|2021|p=663}}

The northern Vietic varieties thus became part of the [[Mainland Southeast Asia linguistic area]], in which languages from genetically unrelated families converged toward characteristics such as [[Isolating language|isolating morphology]] and similar syllable structure.{{sfn|Alves|2021|p=659}} Many languages in this area, including Viet–Muong, underwent a process of [[tonogenesis]], in which distinctions formerly expressed by final consonants became phonemic [[tone (linguistics)|tonal distinctions]] when those consonants disappeared. These characteristics have become part of many of the genetically unrelated languages of Southeast Asia; for example, [[Tsat language|Tsat]] (a member of the [[Malayo-Polynesian languages|Malayo-Polynesian]] group within [[Austronesian languages|Austronesian]]), and Vietnamese each developed tones as a phonemic feature.

[[File:An Nam dịch ngữ.jpg|thumb|An Nam quốc dịch ngữ 安南國譯語 records the pronunciations of 15th-century Vietnamese, such as for 天 (sky) - 雷 /luei/ representing blời (Modern Vietnamese: trời).<ref name=":5" />]]
After the split from Muong around the end of the first millennium AD, the following stages of Vietnamese are commonly identified:{{sfn|Alves|2020|p=xviii}}
;Ancient (or Old) Vietnamese
:(to {{circa|lk=no|1500}}) Sources include the Ming glossary {{tlit|zh|Ānnánguó yìyǔ}} ({{lang|zh|安南國譯語}}, c. 15th century) from the ''[[Huayi yiyu]]'' series,{{efn|The Bureau of Interpreters used Chinese approximations to record Vietnamese rather than use Sino-Vietnamese to record as has been done in Annan Yiyu 安南譯語, a prior work.<ref name=":5">{{Cite book |last=Vương |first=Lộc |title=An Nam dịch ngữ |date=1995 |publisher=NXB Đà Nẵng |location=Vietnam |language=vi}}</ref>}} and a Buddhist sutra recorded in an early form of chu Nom, variously dated to the 12th and 15th centuries.{{sfn|Nguyễn|2009|p=678}}{{sfn|Shimizu|2015|p=136}} Compared with Proto-Vietic, the language had lost the voicing distinction on stop initials, giving rise to a [[tone split]], and [[implosive consonant|implosive]] initials had become [[nasal consonant|nasal]]s.{{sfn|Shimizu|2015|pp=151–152}} Most of the minor syllables of Proto-Vietic were still present.{{sfn|Shimizu|2015|pp=141–142}}
;Middle Vietnamese
:(16th to 19th centuries) The language found in ''[[Dictionarium Annamiticum Lusitanum et Latinum]]'' (1651) of the Jesuit missionary [[Alexandre de Rhodes]].{{sfn|Nguyễn|2009|p=678}} Another famous dictionary of this period was written by [[Pierre Pigneau de Behaine]] in 1773 and published by [[Jean-Louis Taberd]] in 1838.
;Modern Vietnamese
:(from the 19th century){{sfn|Nguyễn|2009|p=678}}

After expelling the Chinese at the beginning of the 10th century, the [[Ngô dynasty]] adopted [[Classical Chinese]] as the formal medium of government, scholarship and literature. With the dominance of Chinese came wholesale importation of Chinese vocabulary. The resulting [[Sino-Vietnamese vocabulary]] makes up about a third of the Vietnamese lexicon in all realms, and may account for as much as 60% of the vocabulary used in formal texts.{{sfn|DeFrancis|1977|p=8}}

Vietic languages were confined to the northern third of modern Vietnam until the "southward advance" ([[Nam tiến]]) from the late 15th century.{{sfn|Sidwell|Alves|2021|p=187}}
The conquest of the ancient nation of [[Champa]] and the conquest of the [[Mekong Delta]] led to an expansion of the Vietnamese people and language, with distinctive local variations emerging.

After France invaded Vietnam in the late 19th century, French gradually replaced Literary Chinese as the official language in education and government. Vietnamese adopted many French terms, such as {{lang|vi|đầm}} ('dame', from {{lang|fr|madame}}), {{lang|vi|ga}} ('train station', from {{lang|fr|gare}}), {{lang|vi|sơ mi}} ('shirt', from {{lang|fr|chemise}}), and {{lang|vi|búp bê}} ('doll', from {{lang|fr|poupée}}), resulting in a language that was Austroasiatic but with major Sino-influences and some minor French influences from the French colonial era.

===Proto-Vietic{{anchor|Proto-Vietnamese}}===
The following diagram shows the consonants of Proto-Vietic, along with the outcomes in the modern language:{{sfn|Ferlus|1992|p=111}}{{sfn|Ferlus|2009|p=96}}<ref name="ferlus1982">
{{citation
|last=Ferlus
|first=Michel
|title=Spirantisation des obstruantes médiales et formation du système consonantique du vietnamien 
|url=https://halshs.archives-ouvertes.fr/halshs-01063845
|year=1982
|journal=Cahiers de Linguistique Asie Orientale
|volume=11
|issue=1
|pages=83–106
|doi=10.3406/clao.1982.1105}}.
</ref>{{efn|The branch Ferlus called Viet–Muong is today called Vietic, with the former term now restricted to the subbranch contsisting of Vietnames and Muong.{{sfn|Ferlus|2009|p=95}}}}

:{| class="wikitable"
|+ Proto-Vietic consonants
|-
! colspan="2" |
! [[labial consonant|Labial]]
! [[Alveolar consonant|Alveolar]]
! [[Palatal consonant|Palatal]]
! [[Velar consonant|Velar]]
! [[glottal consonant|Glottal]]
|-
! colspan="2" |[[Nasal stop|Nasal]]
|*{{IPA|m}} > ''m''
|*{{IPA|n}} > ''n''
|*{{IPA|ɲ}} > ''nh''
|*{{IPA|ŋ}} > ''ng/ngh''
|
|-
! rowspan="4" | [[Stop consonant|Stop]]
! <small>tenuis</small>
| *{{IPA|p}} > ''b''
| *{{IPA|t}} > ''đ''
| *{{IPA|c}} > ''ch''
| *{{IPA|k}} > ''k/c/q''
| *{{IPA|ʔ}} > ''#''
|-
! <small>voiced</small>
| *{{IPA|b}} > ''b''
| *{{IPA|d}} > ''đ''
| *{{IPA|ɟ}} > ''ch''
| *{{IPA|ɡ}} > ''k/c/q''
|
|-
! <small>aspirated</small>
| *{{IPA|pʰ}} > ''ph''
| *{{IPA|tʰ}} > ''th''
|
| *{{IPA|kʰ}} > ''kh''
|
|-
! <small>implosive</small>
| *{{IPA|ɓ}} > ''m''
| *{{IPA|ɗ}} > ''n''
| *{{IPA|ʄ}} > ''nh''
|
|
|-
! colspan="2" | [[Affricate consonant|Affricate]]
|
|
| *{{IPA|tʃ}} > ''x''
|
|
|-
! colspan="2" | [[Fricative]]
|
| *{{IPA|s}} > ''t''
|
|
| *{{IPA|h}} > ''h''
|-
! colspan="2" | [[Approximant]]
| *{{IPA|w}} > ''v''
| *{{IPA|l}} > ''l''
| *{{IPA|j}} > ''d''
|
|
|-
! colspan="2" | [[Rhotic consonant|Rhotic]]
|
| *{{IPA|r}} > ''r''
|
|
|
|}

The aspirated stops are infrequent and result from clusters of stops and *{{IPA|/h/}}.{{sfn|Ferlus|2009|p=96}}
The proto-phoneme *{{IPA|/tʃ/}} is also infrequent, and has reflexes only in Viet-Muong. However, it occurs in some important words and is cognate with [[Khmu language|Khmu]] {{IPA|/c/}}.{{sfn|Ferlus|2009|p=96}}
Ferlus 1992 also had additional [[phoneme]]s *{{IPA|/dʒ/}} and *{{IPA|/ɕ/}}.{{sfn|Ferlus|1992|p=112}}

Proto-Vietic had monosyllables CV(C) and sesquisyllables C-CV(C).{{sfn|Ferlus|2009|p=96}}
The following initial clusters occurred, with outcomes indicated:
* *pr, *br, *tr, *dr, *kr, *gr > {{IPA|/kʰr/}} > {{IPA|/kʂ/}} > ''s''
* *pl, *bl > MV ''bl'' > Northern ''gi'', Southern ''tr''
* *kl, *gl > MV ''tl'' > ''tr''
* *ml > MV ''ml'' > ''mnh'' > ''nh''
* *kj > ''gi''

=== Lenition of medial consonants ===
As noted above, Proto-Vietic had [[sesquisyllabic]] words with an initial [[minor syllable]] (in addition to, and independent of, initial clusters in the main syllable). When a minor syllable occurred, the main syllable's initial consonant was [[intervocalic]] and as a result suffered [[lenition]], becoming a voiced fricative.{{sfn|Ferlus|1992|p=113}} These fricatives were not present in Proto-Viet–Muong, as indicated by their absence in [[Muong language|Mường]], but were present in Vietnamese until the 15th or 16th centuries.{{sfn|Ferlus|1992|p=119}} Subsequent loss of the minor-syllable prefixes phonemicized the fricatives. Ferlus 1992 proposes that originally there were both voiced and voiceless fricatives, corresponding to original voiced or voiceless stops,{{sfn|Ferlus|1992}} but Ferlus 2009 appears to have abandoned that hypothesis, suggesting that stops were softened and voiced at approximately the same time, according to the following pattern:{{sfn|Ferlus|2009|p=96}}
*{{IPA|*p, *b}} > {{IPA|/β/}} > ''v''. In [[Middle Vietnamese]], the outcome of these sounds was written with a hooked ''b'' (ꞗ), representing a {{IPA|/β/}} that was still distinct from ''v'' (then pronounced {{IPA|/w/}}).
*{{IPA|*t, *d}} > {{IPA|/ð/}} > ''d''
*{{IPA|*c, *ɟ, *tʃ}} > {{IPA|/ʝ/}} > ''gi''
*{{IPA|*k, *ɡ}} > {{IPA|/ɣ/}} > ''g/gh''
*{{IPA|*s}} > {{IPA|/r̝/}} > ''r''

===Origin of tones===
Proto-Vietic did not have tones. Tones developed later in some of the daughter languages from distinctions in the initial and final consonants. Vietnamese tones developed as follows:<ref name="Haudricourt 2017 122–128">{{Cite journal|last=Haudricourt|first=André-Georges|date=2017|title=La place du Vietnamien dans les langues Austroasiatiques|trans-title=The place of Vietnamese in Austroasiatic (1953)|url=https://halshs.archives-ouvertes.fr/halshs-01631477/document|journal=Bulletin de la Société de Linguistique de Paris|volume=49|issue=1|pages=122–128}}</ref>

:{| class="wikitable" style="text-align:center;"
|-
! [[Register (phonology)|Register]]
! Initial consonant
! Smooth ending
! Glottal ending
! Fricative ending
|-
! High (first) register
| Voiceless
| A1 ''ngang'' "level"
| B1 ''sắc'' "sharp"
| C1 ''hỏi'' "asking"
|-
! Low (second) register
| Voiced
| A2 ''huyền'' "deep"
| B2 ''nặng'' "heavy"
| C2 ''ngã'' "tumbling"
|}

Glottal-ending syllables ended with a glottal stop {{IPA|/ʔ/}}, while fricative-ending syllables ended with {{IPA|/s/}} or {{IPA|/h/}}. Both types of syllables could co-occur with a resonant (e.g. {{IPA|/m/}} or {{IPA|/n/}}).

At some point, a [[tone split]] occurred, as in many other [[Mainland Southeast Asia linguistic area|mainland Southeast Asian languages]]. Essentially, an [[allophonic]] distinction developed in the tones, whereby the tones in syllables with voiced initials were pronounced differently from those with voiceless initials. (Approximately speaking, the voiced [[allotone]]s were pronounced with additional [[breathy voice]] or [[creaky voice]] and with lowered pitch. The quality difference predominates in today's northern varieties, e.g. in [[Hanoi]], while in the southern varieties the pitch difference predominates, as in [[Ho Chi Minh City]].) Subsequent to this, the plain-voiced stops became voiceless and the allotones became new phonemic tones.

The implosive stops ({{IPA|ɓ}}, {{IPA|ɗ}} and {{IPA|ʄ}}) were unaffected, and in fact developed tonally as if they were unvoiced.{{citation needed|date=December 2024}} (This behavior is common to all East Asian languages with implosive stops.)
These stops merged with the corresponding nasals ({{IPA|m}}, {{IPA|n}} and {{IPA|ɲ}}) before the Old Vietnamese period.{{sfn|Ferlus|1992|p=117}}{{sfn|Shimizu|2015|p=152}}

As noted above, consonants following minor syllables became voiced fricatives. The minor syllables were eventually lost, but not until the tone split had occurred. As a result, words in modern Vietnamese with voiced fricatives occur in all six tones, and the tonal register reflects the voicing of the minor-syllable prefix and not the voicing of the main-syllable stop in Proto-Vietic that produced the fricative. For similar reasons, words beginning with {{IPA|/l/}} and {{IPA|/ŋ/}} occur in both registers. (Thompson 1976 reconstructed voiceless resonants to account for outcomes where resonants occur with a first-register tone,<ref>{{cite journal
|last=Thompson
|first=Laurence C.
|title=Proto-Viet–Muong Phonology
|journal=Oceanic Linguistics Special Publications
|volume=13
|series=Austroasiatic Studies Part II
|year=1976
|pages=1113–1203
|publisher=University of Hawai'i Press
|jstor=20019198
}}</ref> but this is no longer considered necessary, at least by Ferlus.)

A large number of words were borrowed from [[Middle Chinese]], forming part of the [[Sino-Vietnamese vocabulary]]. These caused the original introduction of the retroflex sounds {{IPA|/ʂ/}} and {{IPA|/ʈ/}} (modern ''s'', ''tr'') into the language.

===Old Vietnamese===
Old (or Ancient) Vietnamese separated from Muong around the 9th century. The sources for the reconstruction of Old Vietnamese are [[Chu Nom|Nom]] texts, such as the 12th-century/1486 Buddhist scripture ''Phật thuyết Đại báo phụ mẫu ân trọng kinh'' ("Sūtra explained by the Buddha on the Great Repayment of the Heavy Debt to Parents"),{{sfn|Gong|2019|p=60}} old inscriptions, and a late 13th-century (possibly 1293) ''[https://ctext.org/wiki.pl?if=gb&chapter=224481&remap=gb Annan Jishi]'' glossary by Chinese diplomat [[:zh:陈孚|Chen Fu]] (c. 1259 – 1309).{{sfn|Nguyen|2018|p=162}}

:{| class="wikitable" style=text-align:center
|+ Old Vietnamese consonants{{sfn|Shimizu|2015|pp=143–155}}{{sfn|Gong|2019|pp=60–61}}
|-
! colspan="2" |
! [[labial consonant|Labial]]
! [[Alveolar consonant|Alveolar]]
! [[Palatal consonant|Palatal]]
! [[Velar consonant|Velar]]
! [[glottal consonant|Glottal]]
|-
! colspan="2" |[[Nasal stop|Nasal]]
| {{IPA|m}} > ''m''
| {{IPA|n}} > ''n''
| {{IPA|ɲ}} > ''nh''
| {{IPA|ŋ}} > ''ng/ngh''
|
|-
! rowspan="2" | [[Stop consonant|Stop]]
! <small>tenuis</small>
| {{IPA|p}} > ''b''
| {{IPA|t}} > ''đ''
| {{IPA|c}} > ''ch''
| {{IPA|k}} > ''k/c/q''
| {{IPA|ʔ}} > ''#''
|-
! <small>aspirated</small>
| {{IPA|pʰ}} > ''ph''
| {{IPA|tʰ}} > ''th''
|
| {{IPA|kʰ}} > ''kh''
|
|-
! colspan="2" | [[Affricate consonant|Affricate]]
|
|
| {{IPA|tʃ}} > ''x''
|
|
|-
! rowspan="2" | [[Fricative]]
! <small>voiced</small>
| {{IPA|β}} > ''v''
| {{IPA|ð}} > ''d''
| {{IPA|ʝ}} > ''gi''
| {{IPA|ɣ}} > ''g/gh''
|
|-
! <small>voiceless</small>
|
| {{IPA|s}} > ''t''
|
|
| {{IPA|h}} > ''h''
|-
! colspan="2" | [[Approximant]]
| {{IPA|w}} > ''v''
| {{IPA|l}} > ''l''
| {{IPA|j}} > ''d''
|
|
|-
! colspan="2" | [[Rhotic consonant|Rhotic]]
|
| {{IPA|r}} > ''r''
|
|
|
|}

The {{lang|vi|Đại báo}} used Chinese characters phonetically where each word, monosyllabic in Modern Vietnamese, is written with two Chinese characters or in a composite character made of two different characters.{{sfn|Gong|2019|pp=58–59}} This conveys the transformation of the Vietnamese lexicon from sesquisyllabic to fully [[monosyllabic language|monosyllabic]] under the pressure of Chinese linguistic influence, characterized by linguistic phenomena such as the reduction of minor syllables; loss of affixal morphology drifting towards analytical grammar; simplification of major syllable segments, and the change of suprasegment instruments.{{sfn|Gong|2019|p=58}} For example, the modern Vietnamese word {{lang|vi|trời}} 'heaven' was ''*plời'' in Old Vietnamese and ''blời'' in Middle Vietnamese.{{sfn|Gong|2019|pp=55, 59}}

Subsequent changes to initial consonants included:{{sfn|Ferlus|1992|p=119}}
* re-introduction of implosive stops {{IPA|p}} > {{IPA|ɓ}} and {{IPA|t}} > {{IPA|ɗ}}
* {{IPA|s}} > {{IPA|ts}} > {{IPA|t}}
* {{IPA|tʃ}} > {{IPA|ɕ}}
* a merger {{IPA|j}} > {{IPA|ð}}

===Middle Vietnamese===
The writing system used for Vietnamese is based closely on the system developed by [[Alexandre de Rhodes]] for his 1651 ''[[Dictionarium Annamiticum Lusitanum et Latinum]]''. It reflects the pronunciation of the Vietnamese of Hanoi at that time, a stage commonly termed ''Middle Vietnamese'' ({{lang|vi|tiếng Việt trung đại}}). The pronunciation of the "rime" of the syllable, i.e. all parts other than the initial consonant (optional {{IPA|/w/}} glide, vowel nucleus, tone and final consonant), appears nearly identical between Middle Vietnamese and modern Hanoi pronunciation. On the other hand, the Middle Vietnamese pronunciation of the initial consonant differs greatly from all modern dialects, and in fact is significantly closer to the modern Saigon dialect than the modern Hanoi dialect.

[[File:Dictionarium Annamiticum Lusitanum et Latinum (Bayerische Staatsbibliothek).pdf|thumb|right|upright|page=43|The first page of the [[B with flourish|ꞗ]] section in [[Alexandre de Rhodes]]'s {{lang|la|[[Dictionarium Annamiticum Lusitanum et Latinum]]}} (''Vietnamese–Portuguese–Latin dictionary'')]]
The following diagram shows the orthography and pronunciation of Middle Vietnamese:

:{| class="wikitable" style=text-align:center
|+ Middle Vietnamese consonants
|-
! colspan="2" |
! [[labial consonant|Labial]]
! [[Dental consonant|Dental]]/<br />[[Alveolar consonant|Alveolar]]
! [[Retroflex consonant|Retroflex]]
! [[Palatal consonant|Palatal]]
! [[Velar consonant|Velar]]
! [[glottal consonant|Glottal]]
|-
! colspan="2" | [[Nasal consonant|Nasal]]
| ''m'' {{IPAblink|m}}
| ''n'' {{IPAblink|n}}
|
| ''nh'' {{IPAblink|ɲ}}
| ''ng/ngh'' {{IPAblink|ŋ}}
|
|-
! rowspan="3" | [[Stop consonant|Stop]]
! <small>tenuis</small>
| ''p'' {{IPAblink|p}}{{ref|p|1}}
| ''t'' {{IPAblink|t}}
| ''tr'' {{IPAblink|ʈ}}
| ''ch'' {{IPAblink|c}}
| ''c/k'' {{IPAblink|k}}
|
|-
! <small>aspirated</small>
| ''ph'' {{IPAblink|pʰ}}
| ''th'' {{IPAblink|tʰ}}
|
|
| ''kh'' {{IPAblink|kʰ}}
|
|-
! <small>implosive</small>
| ''b'' {{IPAblink|ɓ}}
| ''đ'' {{IPAblink|ɗ}}
|
|
|
|
|-
! rowspan="2" | [[Fricative consonant|Fricative]]
! <small>voiceless</small>
|
|
| ''s'' {{IPAblink|ʂ}}
| ''x'' {{IPAblink|ɕ}}
|
| ''h'' {{IPAblink|h}}
|-
! <small>voiced</small>
| ''ꞗ'' {{IPAblink|β}}{{ref|hookb|2}}
| ''d'' {{IPAblink|ð}}
|
| ''gi'' {{IPAblink|ʝ}}
| ''g/gh'' {{IPAblink|ɣ}}
|
|-
! colspan="2" | [[Approximant consonant|Approximant]]
| ''v/u/o'' {{IPAblink|w}}
| ''l'' {{IPAblink|l}}
|
| ''y/i/ĕ'' {{IPAblink|j}}{{ref|yod|3}}
|
|
|-
! colspan="2" | [[Rhotic consonant|Rhotic]]
|
| colspan="2" | ''r'' {{IPAblink|r}}
|
|
|
|}

{{note|p|1}} {{IPA|[p]}} occurs only at the end of a syllable.<br />
{{note|hookb|2}} This letter, {{angbr|[[ꞗ]]}}, is no longer used.<br />
{{note|yod|3}} {{IPA|[j]}} does not occur at the beginning of a syllable, but can occur at the end of a syllable, where it is notated ''i'' or ''y'' (with the difference between the two often indicating differences in the quality or length of the preceding vowel), and after {{IPA|/ð/}} and {{IPA|/β/}}, where it is notated ''ĕ''. This ''ĕ'', and the {{IPA|/j/}} it notated, have disappeared from the modern language.

Note that ''b'' {{IPA|[ɓ]}} and ''p'' {{IPA|[p]}} never contrast in any position, suggesting that they are allophones.

The language also has three clusters at the beginning of syllables, which have since disappeared:

*''tl'' {{IPA|/tl/}} > modern ''tr'' - tlước > trước (written in chữ Nôm as 𫏾 (⿰車畧) where 車 represented the initial tl- sound).
*''bl'' {{IPA|/ɓl/}} > modern ''gi'' (Northern), ''tr'' (Southern) - blăng > trăng/giăng (written in chữ Nôm as 𪩮 (⿱巴夌) where 巴 represented the initial bl- sound).
*''ml'' {{IPA|/ml/}} > ''mnh'' {{IPA|/mɲ/}} > modern ''nh'' (Northern), l (Southern) - mlời > lời/nhời (written in chữ Nôm as 𠅜 (⿱亠例) where 亠 (simplified from 麻) represented the initial ml- sound).

[[File:Dictionarium Annamiticum Lusitanum et Latinum, breve acute apex.png|thumb|right|de Rhodes's entry for {{lang|vi|dĕó{{apex|u}}}} shows distinct [[breve]]s, [[acute accent|acutes]] and [[Vietnamese tilde|apices]].]]
Most of the unusual correspondences between spelling and modern pronunciation are explained by Middle Vietnamese. Note in particular:
*de Rhodes' system has two different b letters, {{angle bracket|b}} and {{angle bracket|ꞗ}}. The latter apparently represented a [[voiced bilabial fricative]] {{IPA|/β/}}. Within a century or so, both {{IPA|/β/}} and {{IPA|/w/}} had merged as {{IPA|/v/}}, spelled as ''v''.
*de Rhodes' system has a second medial glide {{IPA|/j/}} that is written ''ĕ'' and appears in some words with initial ''d'' and hooked ''b''. These later disappear.
*''đ'' {{IPA|/ɗ/}} was (and still is) [[alveolar consonant|alveolar]], whereas ''d'' {{IPA|/ð/}} was dental. The choice of symbols was based on the dental rather than alveolar nature of {{IPA|/d/}} and its [[allophone]] {{IPA|[ð]}} in Spanish and other Romance languages. The inconsistency with the symbols assigned to {{IPA|/ɓ/}} vs. {{IPA|/β/}} was based on the lack of any such place distinction between the two, with the result that the [[stop consonant]] {{IPA|/ɓ/}} appeared more "normal" than the fricative {{IPA|/β/}}. In both cases, the [[implosive consonant|implosive]] nature of the stops does not appear to have had any role in the choice of symbol.
*''x'' was the [[voiceless alveolo-palatal fricative|alveolo-palatal fricative]] {{IPA|/ɕ/}} rather than the [[voiceless dental sibilant fricative|dental]] {{IPA|/s/}} of the modern language. In 17th-century [[Portuguese language|Portuguese]], the common language of the Jesuits, ''s'' was the [[voiceless alveolar fricative|apico-alveolar sibilant]] {{IPA|/s̺/}} (as still in much of Spain and some parts of Portugal), while ''x'' was a [[Palato-alveolar consonant|palatoalveolar]] {{IPA|/ʃ/}}. The similarity of apicoalveolar {{IPA|/s̺/}} to the Vietnamese [[retroflex consonant|retroflex]] {{IPA|/ʂ/}} led to the assignment of ''s'' and ''x'' as above.

De Rhodes's orthography also made use of an [[Vietnamese tilde|apex]] diacritic on ''{{apex|o}}'' and ''{{apex|u}}'' to indicate a final [[labial-velar nasal]] {{IPA|/ŋ͡m/}}, an allophone of {{IPA|/ŋ/}} that is peculiar to the Hanoi dialect to the present day. An example is {{wt|mkh-mvi|xa{{apex|o}}}} {{IPA|/ɕawŋ͡m<sup>A1</sup>/}}, which later became {{wt|vi|xong}}. This diacritic is often mistaken for a tilde in modern reproductions of early Vietnamese writing.

=== After the Vietnam War ===
{{see also|Vietnamese language in the United States}}
Following the defeat of Southern Vietnam in 1975 by Northern Vietnam in the Vietnam War, the Vietnamese language within Vietnam has gradually shifted towards the Northern dialect.<ref name=":2">{{Cite web |title=The Non Issue of Dialect in Teaching Vietnamese |url=https://people.clas.ufl.edu/apham/files/The-Non-Issue-of-Dialect-in-Teaching-Vietnamese-2008.pdf}}</ref> [[Hanoi]], the largest city in Northern Vietnam was made the capital of Vietnam in 1976. A study stated that "The gap in vocabulary use between speakers in North and South Vietnam is now much narrower than before. There is little to distinguish between how the generations that were born and grew up in the South after 1975 now speak, compared to their peers in the North. This gap is almost non-existent in newspapers, on radio and television, and in websites."<ref name=":2" /> However, this convergence does not apply to emigrants, in which the study states represent "[[culture freeze]]," a phenomenon that describes when culture among emigrants is frozen in time and does not evolve with culture in their home country once they move to a new country. Here, culture freeze describes that the use of the language of emigrants from Vietnam has been "frozen" in both vocabulary and pronunciation, and as languages gradually evolve over time, has become a little different than the present Vietnamese language in Vietnam. Additionally, as immigration to the United States following the Vietnam war was primarily driven due to political reasons, the Southern Vietnamese dialect was initially strongly linked to social identity. During and after the Vietnam War, thousands of Southern Vietnamese immigrated to the United States with the partnership between Saigon and the US.<ref>{{Cite web |title=Resettling Vietnamese Refugees in the United States |url=https://education.nationalgeographic.org/resource/resettling-vietnamese-refugees-united-states/ |access-date=2025-01-15 |website=education.nationalgeographic.org |language=en}}</ref><ref>{{Cite web |last=Batalova |first=Jeanne Batalova Jeanne |date=2023-10-10 |title=Vietnamese Immigrants in the United States |url=https://www.migrationpolicy.org/article/vietnamese-immigrants-united-states |access-date=2025-01-15 |website=migrationpolicy.org |language=en}}</ref> In contrast, during and following the Vietnam War, thousands of Northern Vietnamese moved to the Czech Republic due to Hanoi's partnership with the now obsolete [[Czechoslovak Socialist Republic]]. As a result, today, the Vietnamese language is generally taught through the Northern dialect in the Czech Republic in contrast with the Southern dialect in the United States.{{fix|link=Wikipedia:Citations needed|text=citation needed|class=Template-Fact}}