A diphthong ( or ; Greek: , 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 moves during the pronunciation of the vowel. In most dialects of English, the words eye, hay, boy, low, and cow contain diphthongs.

Diphthongs contrast with monophthongs, where the tongue doesn't move and only one vowel sound is heard in a syllable. Where two adjacent vowel sounds occur in different syllables, as in, for example, 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).

International Phonetic Alphabet

In the International Phonetic Alphabet, pure vowels are transcribed with one letter, as in English sun . Diphthongs are transcribed with two letters, as in English sign or sane . 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 (an 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 can represent either a diphthong () or two vowels in hiatus ().

Types

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 in eye, while rising (or ascending) diphthongs begin with a less prominent semivowel and end with a more prominent full vowel, similar to the in yard. (Note that "falling" and "rising" in this context do not refer to vowel height; 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 in eye and in yard. However, when the diphthong is analysed as a single phoneme, both elements are often transcribed with vowel letters (, ). 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. ); in opening diphthongs, the second element is more open (e.g. ). Closing diphthongs tend to be falling (), and opening diphthongs are generally rising (), 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 and 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 , .

A centering diphthong is one that begins with a more peripheral vowel and ends with a more central one, such as , , and in Received Pronunciation or and in Irish. Many centering diphthongs are also opening diphthongs (, ).

diphthongs may contrast in how far they open or close. For example, Samoan contrasts low-to-mid with low-to-high diphthongs: ’ai 'probably' ’ae 'but' ’auro 'gold' ao 'a cloud'

Length

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 be 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, while the segmental elements must be different in diphthongs so that , when it occurs in a language, does not contrast with though it is possible to contrast and .

Nonetheless, in practice the choice of treating a diphthong or diphthong-like element as a single phoneme, a sequence of two vowels or a combination of a vowel and a glide is based not on the phonetic nature of the diphthong but on systemic properties of the language. The following are examples of systemic characteristics that tend to determine which analysis is chosen:

The presence of alternations among related words or related dialects between diphthongs and monophthongs, sequences of vowel and consonant, or sequences of two vowels in separate syllables

The restrictions (or lack thereof) on the diphthongs that can occur

The existence of glides such as and as separate phonemes in the language

The behavior of the diphthong when a vowel directly follows

The historical origin of the diphthong

Furthermore, falling diphthongs are more likely to be analyzed as unit phonemes than rising diphthongs.

As an example, the English diphthongs are usually considered single phonemes because they (mostly) originated historically as monophthongs, alternate with monophthongs in pairs such as divine vs. divinity, maintain their coherence when another vowel follows, and other, similar-looking diphthongs like do not exist in the language. On the other hand, Japanese is normally analyzed as a sequence of two vowels; Spanish is normally analyzed as either a sequence of two vowels or of a vowel and a glide, depending on the analysis.

Examples

Germanic languages

English

All English diphthongs are falling, apart from , which can be analyzed as .

rowspan="2" rowspan="2"

+Standard English diphthongs	rowspan="2"			American
GA">Received Pronunciation	! rowspan="2"	American
GA	Canadian English>Canadian
low		>
loud	||
lout
lied	||
light
lane	|
loin	|
loon	|
lean	|
leer	|
lair	|
lure	|

Dutch

+ Diphthongs of Dutch phonology	Dutch	!	Netherlandic	! Belgian
wiktionary:zout#Dutch	zout
wiktionary:beet#Dutch	beet
wiktionary:neus#Dutch	neus
wiktionary:boot#Dutch	boot

The dialect of Hamont (in Limburg) has five centring diphthongs and contrasts long and short forms of , , , and .

German

Standard German

Phonemic diphthongs in German: as in Ei ‘egg’ as in Maus ‘mouse’ as in neu ‘new’

In the varieties of German that vocalize the in the syllable coda, other diphthongal combinations may occur. These are only phonetic diphthongs, not phonemic diphthongs, since the vocalic pronunciation alternates with consonantal pronunciations of if a vowel follows, cf. du hörst ‘you hear’ – ich höre ‘I hear’. These phonetic diphthongs may be as follows: as in er ‘he’ as in ihr ‘you (plural)’ as in Ohr ‘ear’ as in Öhr ‘eye (hole in a needle)’ as in Uhr ‘clock’ as in Tür ‘door’ as in wahr ‘true’

Bernese German

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: as in lieb ‘dear’ as in guet ‘good’ as in müed ‘tired’ as in Bei ‘leg’ as in Boum ‘tree’ 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: as in Stau ‘stable’ as in Staau ‘steel’ as in Wäut ‘world’ as in wääut ‘elects’ as in tschúud ‘guilty’

Yiddish

Yiddish has three diphthongs: as in פּליטה ('refugee' f.) as in נײַן ('nine') as in אופֿן ('way')

Diphthongs may reach a higher target position (towards ) in situations of coarticulatory phenomena or when words with such vowels are being emphasized.

Norwegian

There are five diphthongs in Norwegian:

as in nei, "no" as in øy, "island" as in sau, "sheep" as in hai, "shark" as in joik, "Sami song"

An additional diphthong, , 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.

Faroese

Diphthongs in Faroese are: as in bein (can also be short) as in havn as in har, mær as in hey as in nevnd as in nøvn as in hús as in mín, bý, ið (can also be short) as in ráð as in hoyra (can also be short) as in sól, ovn

Icelandic

Diphthongs in Icelandic are the following: as in átta, "eight" as in nóg, "enough" as in auga, "eye" as in hæ, "hi" as in þeir, "they"

Combinations of semivowel and a vowel are the following: as in jata, "manger" as in já, "yes" as in joð, "iodine," "jay," "yod" (only in a handful of words of foreign origin) as in jól, "Christmas" as in jötunn, "giant" as in jæja, "oh well"

Romance languages

French

In French, , , and may be considered true diphthongs (that is, fully contained in the syllable nucleus: ). 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.

Diphthongs as in roi "king" as in groin "muzzle" as in huit "eight"

Semivowels as in oui "yes" as in lien "bond" as in Ariège as in travail "work" as in Marseille as in feuille "leaf" as in grenouille "frog" as in vieux "old"

Catalan

Catalan possesses a number of phonetic diphthongs, all of which begin (rising diphthongs) or end (falling diphthongs) in or .

'water' mainada remei rei noi avui 'grandma' veiem feiaiodeiogurt

+Catalan diphthongs
colspan="6"	falling
<		aigua	|		taula	'table'
	|	'children'		caurem	'we will fall'
	|	'remedy'		peu	'foot'
	|	'king'		seu	'his/her'
colspan="3"		|	niu	'nest'
	|	'boy'		nou	'new'
colspan="3"		|	pou	'well'
	|	'today'		duu	'he/she is carrying'
colspan="6">rising
	iaia	|		quatre	'four'
	|	'we see'
colspan="3"		|	següent	'following'
	|	'he/she was doing'		aigua	'water'
colspan="3"		|	pingüí	'penguin'
	|	'iodine'		quota	'payment'
	|	'yoghurt'

There are also certain instances of compensatory diphthongization in the Majorcan dialect so that ('logs') (in addition to deleting the palatal plosive) develops a compensating palatal glide and surfaces as (and contrasts with the unpluralized ). 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 ('year') vs ('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's extended to palatals).

Portuguese

The Portuguese diphthongs are formed by the labio-velar approximant and palatal approximant 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 two dialects have slightly different pronunciations. A onglide after or as in quando ('when') or guarda ('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. rowspan=2 colspan=2 colspan=2 rowspan=2 colspan=2 colspan=2

+Falling diphthongs of Portuguese	oral
!	European Portuguese	EP	Brazilian Portuguese>BP	!	European Portuguese>EP	Brazilian Portuguese>BP
sai			mau>
sei	||		meu
anéis	|	véu
colspan="3"		viu>
mói	||colspan="3"|
moita	||	dou
anuis
nasal
mãe	||		mão
cem	>
anões	||colspan="3"|
muita	||colspan="3"|

In addition, phonetic diphthongs are formed in Brazilian Portuguese by the vocalization of in the syllable coda with words like sol ('sun') and sul ('south') as well as by yodization of vowels preceding in words like arroz ('rice') and mas ('but').

Spanish

Spanish has six 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 ('poet') and maestro ('teacher'). The phonemic diphthongs are: 'air'reyhoy 'towards'tierraradioviuda

+ Spanish diphthongs	colspan="6"	falling
<		aire	|		pausa	'pause'
	|	'king'		neutro	'neutral'
	|	'today'		bou	'seine fishing'
colspan="6">rising
	hacia	|		cuadro	'picture'
	|	'earth'		fuego	'fire'
colspan="3"		|	fuimos	'we went'
	|	'radio'		cuota	'quota'
	|	'widow'

Italian

In standard Italian, only falling diphthongs are considered to be true diphthongs. Rising diphthongs are considered to be sequences of approximant and vowel. The diphthongs of Italian are: baitapoteiseipoivoiluichiavepienosoffiettochiodofiorepiuma

+Italian diphthongs	falling
	|	'mountain hut'		auto	'car'
	|	'I could'		pleurite	'pleurisy'
	|	'six'		neutro	'neuter'
	|	'later'
	|	'you' (pl.)
	|	'he'
rising
	|	'key'		guado	'ford'
	|	'full'		quercia	'oak'
	|	'bellows'		quello	'that'
colspan="3"		|	guida	'guide'
	|	'nail'		quota	'quota'
	|	'flower'		acquoso	'watery'
	|	'feather'

In general, unstressed in hiatus can turn into glides in more rapid speech (e.g. biennale 'biennial'; coalizione 'coalition') with the process occurring more readily in syllables further from stress.

Romanian

Romanian has two diphthongs: and . 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 and . To native speakers, they sound very similar to and respectively. There are no perfect minimal pairs to contrast and , and because doesn't appear in the final syllable of a prosodic word, there are no monosyllabic words with ; 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 and can be combined (either before, after, or both) with most vowels, while this arguably forms additional diphthongs and triphthongs, only and can follow an obstruent-liquid cluster such as in broască ('frog') and dreagă ('to mend'). implying that and are restricted to the syllable boundary and therefore, strictly speaking, do not form diphthongs.

Celtic languages

Irish

All Irish diphthongs are falling. , spelled aigh, aidh, agh, adh, eagh, eadh, eigh, or eidh , spelled abh, amh, eabh, or eamh , spelled ia, iai , spelled ua, uai

Slavic languages

Croatian

i(j)e, as in mlijeko is conventionally considered a diphthong. However, it is actually in hiatus or separated by a semivowel, .

Croatian dialects also have uo, as in kuonj, ruod, uon while, in Standard Croatian, these words are konj, rod, on)

Czech

There are three diphthongs in Czech:

as in auto (almost exclusively in words of foreign origin) as in euro (in words of foreign origin only) as in koule

The vowel groups ia, ie, ii, io, and iu in foreign words are not regarded as diphthongs, they are pronounced with between the vowels .

Finno-Ugric languages

Estonian

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.

teadma"to know"toa"room"(s. possessive) colspan="2"

+Common Estonian diphthongs
	|	aed"fence, garden"		lai"wide"		kaotama"to lose"		laud"table"
	|				leib"bread"		teostus"accomplishment"		kiuste"in spite of"
	|		koer"dog"		toit"food"
colspan="2"		||		kui"when, if"
colspan="2"		|	nõel"needle"		õige"right, correct"		tõotus"promise"		lõug"chin"
colspan="2"		|	päev"day"		täis"full"		näo"face" (s. possessive)
colspan="2"		|	söed"coals"		köis"rope"

There are additional diphthongs less commonly used, such as in Euroopa (Europe), in söandama (to dare), and in näuguma (to mew).

Finnish

All Finnish diphthongs are falling. Notably, Finnish has true opening diphthongs (e.g. ), which are not very common crosslinguistically compared to centering diphthongs (e.g. in English). Vowel combinations across syllables may in practice be pronounced as diphthongs, when an intervening consonant has elided, e.g. in näön [næøn] instead of [næ.øn] < genitive of näkö "sight". ; closing as in laiva (ship) as in keinu (swing) as in poika (boy) as in äiti (mother) as in öisin (at nights) as in lauha (mild) as in leuto (mild) as in koulu (school) as in leyhyä (to waft) as in täysi (full) as in löytää (to find) ; close as in uida (to swim) as in lyijy (lead) as in viulu (violin) as in siistiytyä (to smarten up) ; opening as in kieli (tongue) as in suo (bog) as in yö (night)

Northern Sami

The diphthong system in Northern Sami varies considerably from one dialect to another. The Western Finnmark dialects distinguish four different qualities of opening diphthongs:

as in leat "to be" as in giella "language" as in boahtit "to come" 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.

Semitic languages

Maltese

Maltese has seven falling diphthongs, though they may be considered VC sequences phonemically.

ej or għi aj or għi oj iw ew aw or għu ow or għu

Sino-Tibetan languages

Mandarin Chinese

Rising sequences in Mandarin are usually regarded as a combination of a medial semivowel () plus a vowel, while falling sequences are regarded as one diphthong.

ai: , as in ài (愛, love) ei: , as in lèi (累, tired) ao: , as in dào (道, way) ou: , as in dòu (豆, bean)

However, the four rising sequences below can be considered diphthongs as they are analogous to respectively and the bare vowel nucleus mostly only occurs along with the corresponding medial. e: , as in hē (喝, to drink) ye/-ie: , as in xié (斜, tilted) wo/-uo: , as in wǒ (我, I) yue/-üe: , as in yuè (月, moon)

Tai–Kadai languages

Thai

In addition to vowel nuclei following or preceding and , Thai has three diphthongs:

Bantu languages

Zulu

Zulu has only monophthongs. Y and w are semi-vowels:

as in ngiyakubeka (I am placing it) as in ngiwa (I fall/I am falling)

See also

Hiatus

Index of phonetics articles

Table of vowels

Monophthong

Semivowel

Triphthong

Vowel

Vowel cluster

Vowel breaking

Diaeresis

References

Bibliography

Category:Vowels Category:Phonetics

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