A diphthong (// or //; Greek: δίφθογγος, diphthongos, literally "two sounds" or "two tones"), also known as a gliding vowel, refers to two adjacent vowel sounds occurring within the same syllable. Technically, a diphthong is a vowel with two different targets: that is, the tongue (and/or other parts of the speech apparatus) moves during the pronunciation of the vowel. For most dialects of English, the phrase "no highway cowboys" contains five distinct diphthongs.
Diphthongs contrast with monophthongs, where the tongue or other speech organs do not move significantly and the syllable contains only a single vowel sound. Where two adjacent vowel sounds occur in different syllables—for example, in the English word re-elect—the result is described as hiatus, not as a diphthong.
Diphthongs often form when separate vowels are run together in rapid speech during a conversation. However, there are also unitary diphthongs, as in the English examples above, which are heard by listeners as single-vowel sounds (phonemes).
- 1 International Phonetic Alphabet
- 2 Types
- 3 Difference from a vowel and semivowel
- 4 Examples
- 4.1 Germanic languages
- 4.2 Romance languages
- 4.3 Celtic languages
- 4.4 Slavic languages
- 4.5 Finno-Ugric languages
- 4.6 Semitic languages
- 4.7 Sino-Tibetan languages
- 4.8 Tai–Kadai languages
- 4.9 Mon-Khmer languages
- 4.10 Bantu languages
- 5 See also
- 6 References
- 7 Bibliography
International Phonetic Alphabet
In the International Phonetic Alphabet, monophthongs are transcribed with one symbol, as in English sun [sʌn]. Diphthongs are transcribed with two letters, as in English sign [saɪ̯n] or sane [seɪ̯n]. The two vowel symbols are chosen to represent the beginning and ending positions of the tongue, though this can be only approximate.
The non-syllabic diacritic (the inverted breve below: 〈◌̯〉) can be placed under the less prominent component to show that it is part of a diphthong rather than a separate vowel. It is, however, usually omitted in languages such as English, where there is not likely to be any confusion.
Without the diacritic, the sequence [ai] can represent either a diphthong ([ai̯]) or two vowels in hiatus ([a.i]).
Falling and rising
Falling (or descending) diphthongs start with a vowel quality of higher prominence (higher pitch or volume) and end in a semivowel with less prominence, like [aɪ̯] in eye, while rising (or ascending) diphthongs begin with a less prominent semivowel and end with a more prominent full vowel, similar to the [ja] in yard. (Note that "falling" and "rising" in this context do not refer to vowel height; for that, the terms "opening" and "closing" are used instead. See below.) The less prominent component in the diphthong may also be transcribed as an approximant, thus [aj] in eye and [ja] in yard. However, when the diphthong is analysed as a single phoneme, both elements are often transcribed with vowel letters (/aɪ̯/, /ɪ̯a/). Note also that semivowels and approximants are not equivalent in all treatments, and in the English and Italian languages, among others, many phoneticians do not consider rising combinations to be diphthongs, but rather sequences of approximant and vowel. There are many languages (such as Romanian) that contrast one or more rising diphthongs with similar sequences of a glide and a vowel in their phonetic inventory (see semivowel for examples).
Closing, opening, and centering
In closing diphthongs, the second element is more close than the first (e.g. [ai]); in opening diphthongs, the second element is more open (e.g. [ia]). Closing diphthongs tend to be falling ([ai̯]), and opening diphthongs are generally rising ([i̯a]), as open vowels are more sonorous and therefore tend to be more prominent. However, exceptions to this rule are not rare in the world's languages. In Finnish, for instance, the opening diphthongs /ie̯/ and /uo̯/ are true falling diphthongs, since they begin louder and with higher pitch and fall in prominence during the diphthong.
A third, rare type of diphthong that is neither opening nor closing is height-harmonic diphthongs, with both elements at the same vowel height. These were particularly characteristic of Old English, which had diphthongs such as /æɑ̯/, /eo̯/.
A centering diphthong is one that begins with a more peripheral vowel and ends with a more central one, such as [ɪə̯], [ɛə̯], and [ʊə̯] in Received Pronunciation or [iə̯] and [uə̯] in Irish. Many centering diphthongs are also opening diphthongs ([iə̯], [uə̯]).
Diphthongs may contrast in how far they open or close. For example, Samoan contrasts low-to-mid with low-to-high diphthongs:
- ’ai [ʔai̯] 'probably'
- ’ae [ʔae̯] 'but'
- ’auro [ʔau̯ɾo] 'gold'
- ao [ao̯] 'a cloud'
Languages differ in the length of diphthongs, measured in terms of morae. In languages with phonemically short and long vowels, diphthongs typically behave like long vowels, and are pronounced with a similar length. In languages with only one phonemic length for pure vowels, however, diphthongs may behave like pure vowels. For example, in Icelandic, both monophthongs and diphthongs are pronounced long before single consonants and short before most consonant clusters.
Some languages contrast short and long diphthongs. In some languages, such as Old English, these behave like short and long vowels, occupying one and two morae, respectively. In other languages, however, such as Ancient Greek, they occupy two and three morae, respectively, with the first element rather than the diphthong as a whole behaving as a short or long vowel. Languages that contrast three quantities in diphthongs are extremely rare, but not unheard of; Northern Sami is known to contrast long, short and "finally stressed" diphthongs, the last of which are distinguished by a long second element.
Difference from a vowel and semivowel
While there are a number of similarities, diphthongs are not the same as a combination of a vowel and an approximant or glide. Most importantly, diphthongs are fully contained in the syllable nucleus while a semivowel or glide is restricted to the syllable boundaries (either the onset or the coda). This often manifests itself phonetically by a greater degree of constriction. though this phonetic distinction is not always clear. The English word yes, for example, consists of a palatal glide followed by a monophthong rather than a rising diphthong. In addition, the segmental elements must be different in diphthongs so that [ii̯], when it occurs in a language, does not contrast with [iː] though it is possible for languages to contrast [ij] and [iː].
All English diphthongs are falling, apart from /juː/, which can be analyzed as [i̯uː].
In words coming from Middle English, most cases of the Modern English diphthongs [aɪ̯, oʊ̯, eɪ̯, aʊ̯] originate from the Middle English long monophthongs [iː, ɔː, aː, uː] through the Great Vowel Shift, although some cases of [oʊ̯, eɪ̯] originate from the Middle English diphthongs [ɔu̯, aɪ̯].
|loon||[ʊu̯][t2 2]||[ʉː]||[ʊu̯][t2 2]|
|lean||[ɪi̯][t2 2]||[ɪi̯][t2 2]||[ɪi̯][t2 2]|
|lair||[ɛə̯][t2 4]||[eː][t2 4]||[ɛɚ̯][t2 3]|
|lure||[ʊə̯][t2 4]||[ʊə̯]||[ʊɚ̯][t2 3]|
- Canadian English exhibits allophony of /aʊ̯/ and /aɪ̯/ called Canadian raising. GA and RP have raising to a lesser extent in /aɪ̯/.
- The erstwhile monophthongs /iː/ and /uː/ are diphthongized in many dialects. In many cases they might be better transcribed as [uu̯] and [ii̯], where the non-syllabic element is understood to be closer than the syllabic element. They are sometimes transcribed /uw/ and /ij/.
- In rhotic dialects, words like pair, poor, and peer can be analyzed as diphthongs, although other descriptions analyze them as vowels with [ɹ] in the coda.
- In Received Pronunciation, the vowels in lair and lure may be monophthongized to [ɛː] and [oː] respectively (Roach (2004:240)). Australian English speakers more readily monophthongize the former.
Phonemic diphthongs in German:
- /aɪ̯/ as in Ei ‘egg’
- /aʊ̯/ as in Maus ‘mouse’
- /ɔʏ̯/ as in neu ‘new’
In the varieties of German that vocalize the /r/ in the syllable coda, other diphthongal combinations may occur. These are only phonetic diphthongs, not phonemic diphthongs, since the vocalic pronunciation [ɐ̯] alternates with consonantal pronunciations of /r/ if a vowel follows, cf. du hörst [duː ˈhøːɐ̯st] ‘you hear’ – ich höre [ʔɪç ˈhøːʀə] ‘I hear’. These phonetic diphthongs may be as follows:
- [eːɐ̯] as in er ‘he’
- [iːɐ̯] as in ihr ‘you (plural)’
- [oːɐ̯] as in Ohr ‘ear’
- [øːɐ̯] as in Öhr ‘eye (hole in a needle)’
- [uːɐ̯] as in Uhr ‘clock’
- [yːɐ̯] as in Tür ‘door’
- [aːɐ̯] as in wahr ‘true’
The diphthongs of some German dialects differ a lot from standard German diphthongs. The Bernese German diphthongs, for instance, correspond rather to the Middle High German diphthongs than to standard German diphthongs:
- /iə̯/ as in lieb ‘dear’
- /uə̯/ as in guet ‘good’
- /yə̯/ as in müed ‘tired’
- /ei̯/ as in Bei ‘leg’
- /ou̯/ as in Boum ‘tree’
- /øi̯/ as in Böim ‘trees’
Apart from these phonemic diphthongs, Bernese German has numerous phonetic diphthongs due to L-vocalization in the syllable coda, for instance the following ones:
- [au̯] as in Stau ‘stable’
- [aːu̯] as in Staau ‘steel’
- [æu̯] as in Wäut ‘world’
- [æːu̯] as in wääut ‘elects’
- [ʊu̯] as in tschúud ‘guilty’
- [ɛɪ̯] as in [plɛɪ̯tə] פּליטה ('refugee' f.)
- [aɛ̯] as in [naɛ̯n] נײַן ('nine')
- [ɔə̯] as in [ɔə̯fn̩] אופֿן ('way')
Diphthongs may reach a higher target position (towards /i/) in situations of coarticulatory phenomena or when words with such vowels are being emphasized.
There are five diphthongs in Norwegian:
- [æɪ̯] as in nei, "no"
- [øʏ̯] as in øy, "island"
- [æʉ̯] as in sau, "sheep"
- [ɑɪ̯] as in hai, "shark"
- [ɔʏ̯] as in joik, "Sami song"
An additional diphthong, [ʉ̫ʏ̯], occurs only in the word hui in the expression i hui og hast "in great haste". The number and form of diphthongs vary between dialects.
Diphthongs in Faroese are:
- /ai/ as in bein (can also be short)
- /au/ as in havn
- /ɛa/ as in har, mær
- /ɛi/ as in hey
- /ɛu/ as in nevnd
- /œu/ as in nøvn
- /ʉu/ as in hús
- /ʊi/ as in mín, bý, ið (can also be short)
- /ɔa/ as in ráð
- /ɔi/ as in hoyra (can also be short)
- /ɔu/ as in sól, ovn
Diphthongs in Icelandic are the following:
- /au̯/ as in átta, "eight"
- /ou̯/ as in nóg, "enough"
- /œi̯/ as in auga, "eye"
- /ai̯/ as in kær, "dear"
- /ei̯/ as in þeir, "they"
Combinations of semivowel /j/ and a vowel are the following:
- /jɛ/ as in éta, "eat"
- /ja/ as in jata, "manger"
- /jau̯/ as in já, "yes"
- /jo/ as in joð, "iodine," "jay," "yod" (only in a handful of words of foreign origin)
- /jou̯/ as in jól, "Christmas"
- /jœ/ as in jötunn, "giant"
- /jai̯/ as in jæja, "oh well"
In French, /wa/, /wɛ̃/, and /ɥi/ may be considered true diphthongs (that is, fully contained in the syllable nucleus: [u̯a], [u̯ɛ̃], [y̯i]). Other sequences are considered part of a glide formation process that turns a high vowel into a semivowel (and part of the syllable onset) when followed by another vowel.
- /wa/ [u̯a] as in roi "king"
- /wɛ̃/ [u̯ɛ̃] as in groin "muzzle"
- /ɥi/ [y̯i] as in huit "eight"
- /wi/ as in oui "yes"
- /jɛ̃/ as in lien "bond"
- /jɛ/ as in Ariège
- /aj/ as in travail "work"
- /ɛj/ as in Marseille
- /œj/ as in feuille "leaf"
- /uj/ as in grenouille "frog"
- /jø/ as in vieux "old"
- [ɑɔ̯] as in tard "late"
- [aɛ̯] as in père "father"
- [aœ̯] as in fleur "flower"
- [ou̯] as in autre "other"
- [øy̯] as in neutre "neutral"
|[əj]||mainada||'children'||[əw]||caurem||'we will fall'|
|[uj]||avui||'today'||[uw]||duu||'he/she is carrying'|
|[jə]||feia||'he/she was doing'||[wə]||qüestió||'question'|
In standard Eastern Catalan, rising diphthongs (that is, those starting with [j] or [w]) are only possible in the following contexts:
- [j] in word initial position, e.g. iogurt.
- Both occur between vowels as in feia and veiem.
- In the sequences [ɡw] or [kw] and vowel, e.g. guant, quota, qüestió, pingüí (these exceptional cases even lead some scholars to hypothesize the existence of rare labiovelar phonemes /ɡʷ/ and /kʷ/).
There are also certain instances of compensatory diphthongization in the Majorcan dialect so that /ˈtroncs/ ('logs') (in addition to deleting the palatal plosive) develops a compensating palatal glide and surfaces as [ˈtrojns] (and contrasts with the unpluralized [ˈtronʲc]). Diphthongization compensates for the loss of the palatal stop (part of Catalan's segment loss compensation). There are other cases where diphthongization compensates for the loss of point of articulation features (property loss compensation) as in [ˈaɲ] ('year') vs [ˈajns] ('years'). The dialectal distribution of this compensatory diphthongization is almost entirely dependent on the dorsal plosive (whether it is velar or palatal) and the extent of consonant assimilation (whether or not it is extended to palatals).
The Portuguese diphthongs are formed by the labio-velar approximant [w] and palatal approximant [j] with a vowel, European Portuguese has 14 phonemic diphthongs (10 oral and 4 nasal), all of which are falling diphthongs formed by a vowel and a nonsyllabic high vowel. Brazilian Portuguese has roughly the same amount, although the European and non-European dialects have slightly different pronunciations ([ɐj] is a distinctive feature of some southern and central Portuguese dialects, especially that of Lisbon). A [w] onglide after /k/ or /ɡ/ and before all vowels as in quando [ˈkwɐ̃du] ('when') or guarda [ˈɡwaɾðɐ ~ ˈɡwaʁdɐ] ('guard') may also form rising diphthongs and triphthongs. Additionally, in casual speech, adjacent heterosyllabic vowels may combine into diphthongs and triphthongs or even sequences of them.
In addition, phonetic diphthongs are formed in most Brazilian Portuguese dialects by the vocalization of /l/ in the syllable coda with words like sol [sɔw] ('sun') and sul [suw] ('south') as well as by yodization of vowels preceding /s/ or its allophone at syllable coda [ʃ ~ ɕ] in terms like arroz [aˈʁojs ~ ɐˈʁo(j)ɕ] ('rice'), and /z/ (or [ʒ ~ ʑ]) in terms such as paz mundial [ˈpajz mũdʒiˈaw ~ ˈpa(j)ʑ mũdʑiˈaw] ('world peace') and dez anos [ˌdɛjˈz‿ɐ̃nu(j)s ~ ˌdɛjˈz‿ɐ̃nuɕ] ('ten years').
Phonemically, Spanish has seven falling diphthongs and eight rising diphthongs. In addition, during fast speech, sequences of vowels in hiatus become diphthongs wherein one becomes non-syllabic (unless they are the same vowel, in which case they fuse together) as in poeta [ˈpo̯eta] ('poet') and maestro [ˈmae̯stɾo] ('teacher'). The Spanish diphthongs are:
The diphthongs of Italian are:
|[ei̯]||potei||'I could' (past tense)||[eu̯]||pleurite||'pleurisy'|
In general, unstressed /i e o u/ in hiatus can turn into glides in more rapid speech (e.g. biennale [bi̯enˈnaːle] 'biennial'; coalizione [ko̯alitˈtsi̯oːne] 'coalition') with the process occurring more readily in syllables further from stress.
Romanian has two diphthongs: /e̯a/ and /o̯a/. As a result of their origin (diphthongization of mid vowels under stress), they appear only in stressed syllables and make morphological alternations with the mid vowels /e/ and /o/. To native speakers, they sound very similar to /ja/ and /wa/ respectively. There are no perfect minimal pairs to contrast /o̯a/ and /wa/, and because /o̯a/ doesn't appear in the final syllable of a prosodic word, there are no monosyllabic words with /o̯a/; exceptions might include voal ('veil') and trotuar ('sidewalk'), though Ioana Chiţoran argues that these are best treated as containing glide-vowel sequences rather than diphthongs. In addition to these, the semivowels /j/ and /w/ can be combined (either before, after, or both) with most vowels, while this arguably forms additional diphthongs and triphthongs, only /e̯a/ and /o̯a/ can follow an obstruent-liquid cluster such as in broască ('frog') and dreagă ('to mend'). implying that /j/ and /w/ are restricted to the syllable boundary and therefore, strictly speaking, do not form diphthongs.
All Irish diphthongs are falling.
- [əi̯], spelled aigh, aidh, agh, adh, eagh, eadh, eigh, or eidh
- [əu̯], spelled abh, amh, eabh, or eamh
- [iə̯], spelled ia, iai
- [uə̯], spelled ua, uai
There are 9 diphthongs in Scottish Gaelic. Group 1 occur anywhere (eu is usually [eː] before -m, e.g. Seumas). Group 2 are reflexes that occur before -ll, -m, -nn, -bh, -dh, -gh and -mh.
|2||[ai]||ai||saill "grease", cainnt "speech", aimhreit "riot"|
|[ɤi]||oi, ei, ai||loinn "badge", greim "bite", saighdear "soldier"|
|[ɯi]||ui, aoi||druim "back", aoibhneas "joy"|
|[au]||a, ea||cam "crooked", ceann "head"|
|[ɔu]||o||tom "mound", donn "brown"|
For more detailed explanations of Gaelic diphthongs see Scottish Gaelic orthography.
Welsh is traditionally divided into Northern and Southern dialects. In the north, some diphthongs may be short or long according to regular vowel length rules but in the south they are always short (see Welsh phonology). Southern dialects tend to simplify diphthongs in speech (e.g. gwaith /gwaiθ/ is reduced to /gwaːθ/.
|aw||/au, ɑːu/||/au/||mawr 'great'|
|ei||/əi/||/əi/||gweithio 'work' (verb)|
|ew||/ɛu, eːu/||/ɛu/||tew 'fat'|
|oe||/ɔɨ, ɔːɨ/||/ɔi/||moel 'bald'|
|ou||/ɔɨ, ɔːɨ/||/ɔi/||cyffrous 'excited'|
|wy||/ʊɨ, uːɨ/||/ʊi/||pwyll 'sense'|
|yw||/ɨu, əu/||/ɪu, əu/||llyw 'rudder'|
- The plural ending -au is reduced to /a/ in the north and /e/ in the south, e.g. cadau 'battles' is /ˈkada/ (north) or /ˈkade/ (south).
- i(j)e, as in mlijeko
is conventionally considered a diphthong. However, it is actually [ie] in hiatus or separated by a semivowel, [ije].
There are three diphthongs in Czech:
- /aʊ̯/ as in auto (almost exclusively in words of foreign origin)
- /eʊ̯/ as in euro (in words of foreign origin only)
- /oʊ̯/ as in koule
The vowel groups ia, ie, ii, io, and iu in foreign words are not regarded as diphthongs, they are pronounced with /j/ between the vowels [ɪja, ɪjɛ, ɪjɪ, ɪjo, ɪju].
All nine vowels can appear as the first component of an Estonian diphthong, but only [ɑ e i o u] occur as the second component.
"in spite of"
"face" (s. possessive)
There are additional diphthongs less commonly used, such as [eu] in Euroopa (Europe), [øɑ] in söandama (to dare), and [æu] in näuguma (to mew).
All Finnish diphthongs are falling. Notably, Finnish has true opening diphthongs (e.g. /uo/), which are not very common crosslinguistically compared to centering diphthongs (e.g. /uə/ in English). Vowel combinations across syllables may in practice be pronounced as diphthongs, when an intervening consonant has elided, as in näön [næøn] instead of [næ.øn] for the genitive of näkö ('sight').
- [ɑi̯] as in laiva (ship)
- [ei̯] as in keinu (swing)
- [oi̯] as in poika (boy)
- [æi̯] as in äiti (mother)
- [øi̯] as in öisin (at nights)
- [ɑu̯] as in lauha (mild)
- [eu̯] as in leuto (mild)
- [ou̯] as in koulu (school)
- [ey̯] as in leyhyä (to waft)
- [æy̯] as in täysi (full)
- [øy̯] as in löytää (to find)
- [ui̯] as in uida (to swim)
- [yi̯] as in lyijy (lead)
- [iu̯] as in viulu (violin)
- [iy̯] as in siistiytyä (to smarten up)
- [ie̯] as in kieli (tongue)
- [uo̯] as in suo (bog)
- [yø̯] as in yö (night)
The diphthong system in Northern Sami varies considerably from one dialect to another. The Western Finnmark dialects distinguish four different qualities of opening diphthongs:
- /eæ/ as in leat "to be"
- /ie/ as in giella "language"
- /oa/ as in boahtit "to come"
- /uo/ as in vuodjat "to swim"
In terms of quantity, Northern Sami shows a three-way contrast between long, short and finally stressed diphthongs. The last are distinguished from long and short diphthongs by a markedly long and stressed second component. Diphthong quantity is not indicated in spelling.
- [ɛɪ̯] ej or għi
- [ɐɪ̯] aj or għi
- [ɔɪ̯] oj
- [ɪʊ̯] iw
- [ɛʊ̯] ew
- [ɐʊ̯] aw or għu
- [ɔʊ̯] ow or għu
Rising sequences in Mandarin are usually regarded as a combination of a medial semivowel ([j], [w], or [ɥ]) plus a vowel, while falling sequences are regarded as one diphthong.
- ai: [aɪ̯], as in ài (愛, love)
- ei: [eɪ̯], as in lèi (累, tired)
- ao: [ɑʊ̯], as in dào (道, way)
- ou: [oʊ̯], as in dòu (豆, bean)
However, the four rising sequences below can be considered diphthongs as they are analogous to [ɨ], [i], [u] and [y] respectively and the bare vowel nucleus mostly only occurs along with the corresponding medial.
- e: [ɯ̯ʌ], as in hē (喝, to drink)
- ye/-ie: [i̯ɛ], as in xié (斜, tilted)
- wo/-uo: [u̯ɔ], as in wǒ (我, I)
- yue/-üe: [y̯œ], as in yuè (月, moon)
Cantonese has eleven diphthongs.
- aai: [aːi], as in gaai1 (街, street)
- aau: [aːu], as in baau3 (爆, explode)
- ai: [ɐi], as in gai1 (雞, chicken)
- au: [ɐu], as in au1 (勾, hook)
- ei: [ei], as in gei1 (機, machine)
- eu: [ɛːu], as in deu6 (掉, throw)
- iu: [iːu], as in giu3 (叫, call)
- oi: [ɔːi], as in oi3 (愛, love)
- ou: [ou], as in gou1 (高, high)
- ui: [uːi], as in pui4 (陪, accompany)
- eui: [ɵy], as in yeui6 (銳, sharp)
Vietnamese has a fairly large number of diphthongs:
- [iu̯] iu
- [iʌ̯] ia~iê
- [eu̯] êu
- [ɛu̯] eo
- [ɯi̯] ưi
- [ɯu̯] ưu
- [ɯʌ̯] ưa~ươ
- [ʌi̯] ây
- [ʌu̯] âu
- [ɤi̯] ơi
- [ǎi̯] ay
- [ǎu̯] au
- [ai̯] ai
- [au̯] ao
- [u̯a] oa
- [u̯ǎ] oǎ
- [u̯ɛ] oe
- [u̯e] uê
- [u̯ɤ] uơ
- [u̯ʌ] uâ
- [ui̯] ui
- [uʌ̯] ua~uô
- [oi̯] ôi
- [ɔi̯] oi
Khmer language similarly has rich vocalics with an extra distinction of long and short register to the vowels and diphthongs.
Zulu has only monophthongs. Y and w are semi-vowels:
- [ja] as in [ŋijaɠuˈɓɛːɠa] ngiyakubeka (I am placing it)
- [wa] as in [ŋiːwa] ngiwa (I fall/I am falling)
- Index of phonetics articles
- Table of vowels
- Vowel breaking
- "diphthong". Dictionary.com Unabridged. Random House, Inc.
- definition of 'Diphthong' on SIL International, accessed 17 January 2008
- FileFormat.Info, page on combining inverted breve below
- Chițoran (2002a:203)
- Kaye & Lowenstamm (1984:139)
- Schane (1995:588)
- Padgett (2007:1938)
- Schane (1995:606)
- Schane (1995:589, 606)
- Gussenhoven (1992:46)
- Verhoeven (2005:245)
- Verhoeven (2007:221)
- Kleine (2003:263)
- Chitoran (2001:11)
- Carbonell & Llisterri (1992:54)
- Institut d'Estudis Catalans Els diftongs, els triftongs i els hiats – Gramàtica de la Llengua Catalana (provisional draft)
- e.g. Lleó (1970), Wheeler (1979)
- Wheeler (2005:101)
- Mascaró (2002:580–581)
- Mascaró (2002:581)
- Faria (2003:7)
- Cruz-Ferreira (1995:92)
- Barbosa & Albano (2004:230)
- Martínez-Celdrán, Fernández-Planas & Carrera-Sabaté (2003:256)
- Azevedo, Milton M. (2004). Introducción a la lingüística española (in Spanish) (2nd ed.). Upper Saddle River, NJ: Prentice Hall. ISBN 0-13-110959-6.
- Bertinetto & Loporcaro (2005:138)
- Bertinetto & Loporcaro (2005:139)
- Chițoran (2002a:204)
- Chițoran (2002a:206)
- Chițoran (2002b:217)
- See Chițoran (2001:8–9) for a brief overview of the views regarding Romanian semivowels
- Chițoran (2002b:213)
- (Croatian) Vjesnik Babić ne zagovara korijenski pravopis, nego traži da Hrvati ne piju mlijeko nego – mlieko
- Josip Lisac. "Štokavsko narječje: prostiranje i osnovne značajke". Kolo (in Croatian).
- Borg & Azzopardi-Alexander (1997:299)
- Tingsabadh & Abramson (1993:25)
- Birbosa, Plínio A.; Albano, Eleonora C. (2004), "Brazilian Portuguese", Journal of the International Phonetic Association 34 (2): 227–232, doi:10.1017/S0025100304001756
- Bertinetto, Pier Marco; Loporcaro, Michele (2005), "The sound pattern of Standard Italian, as compared with the varieties spoken in Florence, Milan and Rome", Journal of the International Phonetic Association 35 (2): 131–151, doi:10.1017/S0025100305002148
- Borg, Albert J.; Azzopardi-Alexander, Marie (1997), Maltese, Routledge, ISBN 0-415-02243-6
- Carbonell, Joan F.; Llisterri, Joaquim (1992), "Catalan", Journal of the International Phonetic Association 22 (1-2): 53–56, doi:10.1017/S0025100300004618
- Chițoran, Ioana (2001), The Phonology of Romanian: A Constraint-based Approach, Berlin & New York: Mouton de Gruyter, ISBN 3-11-016766-2
- Chițoran, Ioana (2002a), "A perception-production study of Romanian diphthongs and glide-vowel sequences", Journal of the International Phonetic Association 32 (2): 203–222, doi:10.1017/S0025100302001044
- Chițoran, Ioana (2002b), "The phonology and morphology of Romanian diphthongization", Probus 14 (2): 205–246, doi:10.1515/prbs.2002.009
- Cruz-Ferreira, Madalena (1995), "European Portuguese", Journal of the International Phonetic Association 25 (2): 90–94, doi:10.1017/S0025100300005223
- Faria, Arlo (2003), Applied Phonetics: Portuguese Text-to-Speech, University of California, Berkeley, CiteSeerX: 10.1.1.134.8785
- Gussenhoven, Carlos (1992), "Dutch", Journal of the International Phonetic Association 22 (2): 45–47, doi:10.1017/S002510030000459X
- Kaye, Jonathan; Lowenstamm, Jean (1984), "De la syllabicité", in Dell, François; Vergnaud, Jean-Roger; Hirst, Daniel, La forme sonore du langage, Paris: Hermann, pp. 123–159
- Kleine, Ane (2003), "Standard Yiddish", Journal of the International Phonetic Association 33 (2): 261–265, doi:10.1017/S0025100303001385
- Martínez-Celdrán, Eugenio; Fernández-Planas, Ana Ma.; Carrera-Sabaté, Josefina (2003), "Castilian Spanish", Journal of the International Phonetic Association 33 (2): 255–259, doi:10.1017/S0025100303001373
- Mascaró, Joan (1976), Catalan Phonology and the Phonological Cycle (Doctoral thesis), Massachusetts Institute of Technology, retrieved 12 December 2013
- Roach, Peter (2004), "British English: Received Pronunciation", Journal of the International Phonetic Association 34 (2): 239–245, doi:10.1017/S0025100304001768
- Padgett, Jaye (2007), "Glides, Vowels, and Features", Lingua 118 (12): 1937–1955, doi:10.1016/j.lingua.2007.10.002
- Schane, Sanford (1995), "Diphthongization in Particle Phonology", in Goldsmith, John A., The Handbook of Phonological Theory, Blackwell Handbooks in Linguistics, Blackwell, pp. 586–608
- Tingsabadh, M.R. Kalaya; Abramson, Arthur (1993), "Thai", Journal of the International Phonetic Association 23 (1): 24–28, doi:10.1017/S0025100300004746
- Verhoeven, Jo (2005), "Belgian Standard Dutch", Journal of the International Phonetic Association 35 (2): 243–247, doi:10.1017/S0025100305002173, retrieved 12 December 2013
- Verhoeven, Jo (2007), "The Belgian Limburg dialect of Hamont", Journal of the International Phonetic Association 37 (2): 219–225, doi:10.1017/S0025100307002940
- Verhoeven, Jo; Van Bael, C. (2002), "Akoestische kenmerken van de Nederlandse klinkers in drie Vlaamse regio’s", Taal en Tongval 54: 1–23
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