Diphthong

In phonetics, a diphthong (Greek δίφθογγος, "diphthongos", literally "with two sounds") is a vowel combination in a single syllable involving a quick but smooth movement from one vowel to another, often interpreted by listeners as a single vowel sound or phoneme. While "pure" vowels, or monophthongs, are said to have one target tongue position, diphthongs have two target tongue positions. Pure vowels are represented in the International Phonetic Alphabet by one symbol: English "sum" as [səm], for example. Diphthongs are represented by two symbols, for example English "same" as [seɪm], where the two vowel symbols are intended to represent approximately the beginning and ending tongue positions.

Falling diphthongs start with a higher vowel, e.g., [iə], while rising diphthongs end with a higher vowel, e.g., [ai]. In Closing diphthongs, the second element is closer than the first; in opening diphthongs, more opened. A centering diphthong is one that begins with a more peripheral vowel and ends with a more central one, such as [ɪə], [ɛə], and [ʊə] in RP or [iə] and [uə] in Irish. Some languages contrast short and long diphthongs. In Portuguese, diphthongs are divided, like the vowels, in two classes: oral and nasal.

The unstressed elements of the diphthongs may be transcribed as semivowels. However, when the whole diphthong is analysed as being one single phoneme, both elements are often transcribed as vowels.

English

Diphthongs in the General American accent of English:

[aʊ] as in house
[aɪ] as in kite
[eɪ] as in same
[juː] as in few (This is phonemically analyzed as a sequence of a semivowel and a monophthong.)
[oʊ] as in tone
[ɔɪ] as in join

Diphthongs in the Received Pronunciation of British English:

[əʊ] as in hope
[aʊ] as in house
[aɪ] as in kite
[eɪ] as in same
[juː] as in few (This is phonemically analyzed as a sequence of a semivowel and a monophthong.)
[ɔɪ] as in join
[ɪə] as in fear
[ɛə] as in hair (In modern pronunciation this is usually the long vowel [ɛː].)
[ʊə] as in poor

The latter three diphthongs also occur in the Boston accent.

(see International Phonetic Alphabet for English for more)

Diphthongs in Australian English:

[əʉ] as in hope
[æɔ] as in house
[ɑe] as in kite
[æɪ] as in same
[jʉː] as in few (This is phonemically analyzed as a sequence of a semivowel and a monophthong.)
[ɔɪ] as in join
[ɪə] as in fear

Italian

Diphthongs in standard Italian:

falling diphthongs

[ai] as in avrai
[ei] as in dei (preposition)
[ɛi] as in direi
[oi] as in voi
[ɔi] as in poi
[au] as in pausa
[eu] as in Europa
[ɛu] as in feudo

rising diphthongs

[ja] as in piano
[je] as in schietto
[jɛ] as in piede
[jo] as in fiore
[jɔ] as in piove
[ju] as in più
[wa] as in guado
[we] as in quello
[wɛ] as in guerra
[wi] as in qui
[wo] as in tuorlo
[wɔ] as in nuoto

Other combinations (including [ui], [iu], [ii]) are generally considered hiatuses by grammarians; however they are often phonetically true diphthongs, such as in poetry and common speech. Note also that rising diphthongs are considered not true diphthongs by many phoneticians, but sequences of a consonant and a vowel.

French

Some diphthongs in French:

[wa] as in roi
[wi] as in oui
[ɥi] as in huit
[jɛ̃] as in bien
[jɛ] as in Ariège
[aj] as in Travail
[ej] as in Marseille
[œj] as in Feuille

Finnish

Diphthongs in Finnish

[ai] as in laiva
[ei] as in keinu
[oi] as in poika
[ui] as in uida
[yi] as in lyijy
[æi] as in äiti
[øi] as in öisin
[au] as in lauha
[eu] as in leuto
[iu] as in viulu
[ou] as in koulu
[ey] as in leyhyä
[iy] as in siistiytyä
[æy] as in täysi
[øy] as in löytää
[ie] as in kieli
[uo] as in suo
[yø] as in yö

German

Diphthongs in German:

[aɪ] as in Reich
[aʊ] as in Maus
[ɔʏ] as in neu
[eɐ] as in der
[iɐ] as in dir
[oɐ] as in Tor
[øɐ] as in Wörter
[uɐ] as in nur
[yɐ] as in Tür

Some diphthongs in Bernese, a Swiss German dialect:

[iə] as in Bier 'beer'
[yə] as in Füess 'feet'
[uə] as in Schue 'shoes'
[ow] as in Stou 'holdup'
[aw] as in Stau 'stable'
[aːw] as in Staau 'steel'
[æw] as in Wäut 'world'
[æːw] as in wääut 'elects'
[ʊw] as in tschúud 'guilty'

Portuguese

Vowel combinations in Portuguese are divided into three groups: hiatus, a sequence of two random vowels, diphthongs, a sequence of a vowel and /i, u/, which can appear after or before the vowel, and the rare trithongs, with semivowel+vowel+semivowel. Just like the vowels, the diphthongs are divided into two subgroups: the oral diphthongs and the nasal diphtongs.

Diphthongs in Portuguese:

oral

[aj] as in pai
[ɐj] as in peito(in Lisbon)
[ej] as in peito (standard)
[ɛj] as in papéis
[oj] as in coisa
[ɔi] as in mói
[uj] as in fui
[aw] as in mau
[ew] as in teu
[ɛw] as in céu
[iw] as in viu
[ow] as in roupa

nasal

[ɐ̃j̃] as in mãe
[ẽj̃] as in bem
[õj̃] as in põe
[ũj̃] as in muita
[ɐ̃w̃] as in são

Northern Sami

Diphthongs in Northern Sami

[eæ] as in leat
[ie] as in giella
[oa] as in boahtit
[uo] as in vuodjat

Romanian

Romanian builds its descending diphthongs using two semivowels and its ascending diphthongs using four. See also Romanian phonology.

Descending:

[aĭ] as in mai
[aŭ] as in dau
[eĭ] as in lei
[eŭ] as in leu
[iĭ] as in mii (no vocalic glide, but still a diphthong)
[iŭ] as in fiu
[oĭ] as in goi
[oŭ] as in nou
[uĭ] as in pui
[əĭ] as in răi
[əŭ] as in rău
[ɨĭ] as in câine
[ɨŭ] as in râu

Ascending:

[ĕa] as in stea
[ĕo] as in George
[ĭa] as in ziar
[ĭe] as in fier
[ĭo] as in chior
[ĭu] as in iubit
[ŏa] as in oameni
[ŭa] as in ziua
[ŭə] as in două

Spanish

Diphthongs in Spanish:

rising diphthongs

[ai] as in hay
[ei] as in rey
[oi] as in hoy
[ui] as in muy
[au] as in Jauja
[eu] as in feudo

falling diphthongs

[ja] as in comedia
[je] as in tierra
[jo] as in dio
[ju] as in ciudad
[wa] as in guante
[we] as in fuego
[wo] as in ambiguo