Diphthong

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A diphthong (pronounced /ˈdɪfθɒŋ/ or /ˈdɪpθɒŋ/; from 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.  In most dialects of English, the words eye, boy, and cow contain examples of diphthongs.

Diphthongs contrast with monophthongs, where 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 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 diacritic [<ɶnbsp;ɶnbsp;̯>] is placed under the less prominent component to show that it is part of a diphthong rather than a separate vowel, though it is sometimes omitted in languages such as English, where there is not likely to be any confusion. (In precise transcription, ai represents two vowels in hiatus, found for example in Hawaiian and in the English word naïve, and does not represent the diphthong, for instance, in the Finnish word laiva, "ship").

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 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; 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.

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.^{[citation needed]} These were particularly characteristic of Old English, which had diphthongs such as [/æɑ/], [/eo/].

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).

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.^{[citation needed]} In languages with only one phonemic length for pure vowels, however, diphthongs may be behave like pure vowels.^{[citation needed]} 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.^{[citation needed]} 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.^{[citation needed]}

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 ii̯, when it occurs in a language, does not contrast with iː though it is possible to contrast ij and iː.

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.^{[citation needed]} The following are examples of systemic characteristics that tend to determine which analysis is chosen:^{[citation needed]}

• 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 [/w/] and [/j/] 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 [/eu/] do not exist in the language.^{[citation needed]} On the other hand, Japanese [/ai/] is normally analyzed as a sequence of two vowels; Spanish [/ai/] is normally analyzed as either a sequence of two vowels or of a vowel and a glide, depending on the analysis.^{[citation needed]}

Examples

Germanic languages

English

See also: IPA chart for English dialects

All English diphthongs are falling, apart from [/juː/], which can be analyzed as i̯uː.

Standard English diphthongs

	RP (British)	Australian	American
			GA	Canadian
low	əʊ̯	əʉ̯	oʊ̯
loud	aʊ̯	æɔ̯	aʊ̯	aʊ̯
lout				əʊ̯
lied	aɪ̯	ɑe̯	aɪ̯
light			əɪ̯
lane	eɪ̯	æɪ̯	eɪ̯
loin	ɔɪ̯	oɪ̯	ɔɪ̯
loon	uː	ʉː	ʊu̯
lean	iː	ɪi̯	ɪi̯
leer	ɪə̯	ɪə̯	ɪɚ̯
lair	ɛə̯	eː	ɛɚ
lure	ʊə̯	ʊə̯	ʊɚ̯

Dutch

Diphthongs of Dutch

	Netherlandic	Belgian
zeis	ɛɪ̯
ui	œʏ̯
zout	ʌʊ̯	ɔʊ̯
beet	eɪ̯	eː
neus	øʏ̯	øː
boot	oʊ̯	oː

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

German

Standard German

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’

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:

• [/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’

Yiddish

Yiddish has three diphthongs:

• ɛɪ̯ as in plɛɪ̯tə פּליטה ('refugee' f.)
• aɛ̯ as in naɛ̯n נײַן ('nine')
• ɔə̯ as in ɔəf̯n̩ 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.

Norwegian

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.

Faroese

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

Icelandic

Diphthongs in Icelandic are the following:

• [/aw/] as in átta, "eight"
• [/ow/] as in nóg, "enough"
• [/œɥ/] as in auga, "eye"
• [/aj/] as in hæ, "hi"
• [/ej/] as in þeir, "they"

Combinations of j and a vowel are the following:

• [/ja/] as in jata, "manger"
• [/jaw/] as in já, "yes"
• [/jo/] as in joð, "iodine," "jay," "yod" (only in a handful of words of foreign origin)
• [/jow/] as in jól, "Christmas"
• [/jœ/] as in jötunn, "giant"
• [/jaj/] as in jæja, "oh well"

Romance languages

French

In French, [/wa/], [/wɛ̃/], and [/ɥi/] may be considered diphthongs (that is, fully contained in the syllable nucleus). Other sequences of a glide and vowel are considered part of a glide formation process that turns a high vowel into a glide (and part of the syllable onset) when followed by another vowel.

• [/wa/] as in roi "king"
• [/wɛ̃/] as in groin "muzzle"
• [/ɥi/] 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"
• [/ɑj/] as in maille

Catalan

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

Catalan diphthongs

falling
aj	aigua	'water'	aw	taula	'table'
əj	mainada	'children'	əw	caurem	'we will fall'
ɛj	remei	'remedy'	ɛw	peu	'foot'
ej	rei	'king'	ew	seu	'his/her'
			iw	niu	'nest'
ɔj	noi	'boy'	ɔw	nou	'new'
			ow	pou	'well'
uj	avui	'today'	uw	duu	'he/she is carrying'
rising
ja	iaia	'grandma'	wa	quatre	'four'
jɛ	veiem	'we see'
			we	següent	'following'
jə	feia	'he/she was doing'	wə	aigua	'water'
			wi	pingüí	'penguin'
jɔ	iode	'iodine'	wɔ	quota	'payment'
ju	iogurt	'yoghurt'

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

Portuguese

Main article: Portuguese phonology

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 two dialects have slightly different pronunciations. A w onglide after [/k/] or [/ɡ/] as in quando ˈkwɐ̃dʊ ('when') or guarda ˈɡwaɾdɐ ('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.

Falling diphthongs of Portuguese

	EP	BP
sai	aj
sei	ɐj	ej
anéis		ɛj
mói	ɔj
moita	oj
anuis	uj
viu	iw
meu	ew
véu	ɛw
mau	aw
cem	ɐ̃j	ẽj
mãe		ɐ̃j
anões	õj
muita	ũj
mão	ɐ̃w

In addition, phonetic diphthongs are formed in Brazilian Portuguese 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/] in words like arroz aˈʁojs ('rice') and mas majs ('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 ˈpo̯eta ('poet') and maestro ˈmae̯stɾo ('teacher'). The phonemic diphthongs are:

falling
[/ei̯/] as in rey ('king') [/ai̯/] as in aire ('air') [/oi̯/] as in hoy ('today')	[/eu̯/] as in neutro ('neutral') [/au̯/] as in pausa ('pause') [/ou̯/] as in bou ('seine fishing')

rising
[/je/] as in tierra ('earth') [/ja/] as in hacia ('towards') [/jo/] as in radio ('radio') [/ju/] as in viuda ('widow')	[/wi/] as in fuimos ('we went') [/we/] as in fuego ('fire') [/wa/] as in cuadro ('picture') [/wo/] as in cuota ('quota')

Italian

In standard Italian, only falling diphthongs are considered to be true diphthongs. Rising diphthongs are considered to be sequences of approximant and vowel.^{[citation needed]} The diphthongs of Italian are:

falling

• ei̯ as in potei ('could 1.sg.')
• ɛi̯ as in sei ('six')
• ai̯ as in baita ('mountain hut')
• ɔi̯ as in poi ('later')
• oi̯ as in voi ('you pl.')
• ui̯ as in lui ('he')
• eu̯ as in pleurite ('pleuritis')
• ɛu̯ as in neutro ('neuter')
• au̯ as in auto ('car')

rising

• je as in soffietto ('bellows')
• jɛ as in pieno ('full')
• ja as in chiave ('key')
• jɔ as in chiodo ('nail')
• jo as in fiore ('flower')
• ju as in piuma ('feather')
• wi as in guida ('guide')
• we as in quello ('that')
• wɛ as in quercia ('oak')
• wa as in guado ('ford')
• wɔ as in quota ('quota')
• wo as in acquoso ('watery')

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

Romanian

Main article: Romanian phonology

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.

Celtic languages

Irish

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

Slavic languages

Croatian

• i(j)e, as in mlijeko

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:

• [/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.

Finno-Ugric languages

Finnish

Main article: Finnish phonology

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).

closing

• ai̯ 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)
• au̯ 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)

close

• ui̯ as in uida (to swim)
• yi̯ as in lyijy (lead)
• iu̯ as in viulu (violin)
• iy̯ as in siistiytyä (to smarten up)

opening

• ie̯ as in kieli (tongue)
• uo̯ as in suo (bog)
• yø̯ 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:

• [/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.

Semitic languages

Maltese

Maltese has seven falling diphthongs.

• ɛɪ̯ ej or għi
• ɐɪ̯ aj or għi
• ɔɪ̯ oj
• ɪʊ̯ iw
• ɛʊ̯ ew
• ɐʊ̯ aw or għu
• ɔʊ̯ ow or għu

Sino-Tibetan languages

Mandarin Chinese

Rising diphthongs in Mandarin are usually regarded as a combination of a medial glide (i, u, or ü) and a final segment, while falling diphthongs are seen as one final segment. Tone marker is always placed on the vowel with more prominence.

rising

Glide	Rime		Pinyin
i	ä	i̯ä	ia/ya	jiā (家, home), yā (鴨, duck)
	an	i̯ɛn	ian/yan	jiǎn (剪, to cut), yǎn (眼, eye) 2
	ɑŋ	i̯ɑŋ	iang/yang	xiǎng (想, to think), yǎng (癢, itchy) 2
	ɛ	i̯ɛ	ie/ye	xiè (謝, to thank), yè (葉, leaf)
	ɔ	i̯ɔ	yo	yō (唷, an interjection) 1
u	ä	u̯ä	ua/wa	guā (瓜, melon), wā (挖, to dig)
	an	u̯än	uan/wan	guǎn (管, tube), wǎn (碗, bowl)
	ɑŋ	u̯ɑŋ	uang/wang	zhuāng (裝, to fill), wàng (忘, to forget) 2
	ɔ	u̯ɔ	uo/wo	huǒ (火, fire), wǒ (我, I)
	ən	u̯ən	un/wen	wèn (問, to ask) 2
	əŋ	u̯ɤŋ	weng	wēng (翁, old man) 12
y	an	y̯ɛn	üan/yuan	xüǎn (選, to choose), yuǎn (遠, far) 2
	ɛ	y̯ɛ	üe/yue	xüé (學, to learn), yuè (越, to cross)
	əŋ	i̯ʊŋ	iong/yong	xiōng (兇, menacing), yǒng (永, forever) 2

falling

• 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)

¹ only occurs in isolation

² always followed by nasal

Tai-Kadai languages

Thai

In addition to vowel nuclei following [/j/] and [/w/], Thai has three diphthongs:

• ia̯
• ɯa̯
• ua̯

Bantu languages

Zulu

Diphthongs between true vowels never occur in Zulu, with each syllable having only one vowel sound, e.g. iːǃaːǃa. However, Zulu has two semi-vowels which form diphthongs with vowels:

• ja as in ŋijaɠuˈɓɛːɠa ngiyakubeka (I am placing it)
• wa as in ŋiːwa ngiwa (I fall/I am falling)

See also

• Hiatus
• Index of phonetics articles
• Semivowel
• Triphthong
• Vowel cluster
• Vowel breaking

Bibliography

• Barbosa, 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 
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diphthong

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