Diphthong

In phonetics, a diphthong (Greek δίφθογγος, "diphthongos", literally "with two sounds," or "with two tones") 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 /sʌm/, 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 vowel of higher sonority and end in a vowel with less sonority, e.g., /ai̯/, while rising diphthongs begin with a vowel with less sonority and end with a vowel of higher sonority, e.g., /i̯a/. The element with less sonority in the diphthong may be transcribed as semivowel. However, when the whole diphthong is analysed as being one single phoneme, both elements are often transcribed as vowels. Note also that in languages like English and Italian, rising diphthongs are considered not true diphthongs by many phoneticians, but sequences of a semivowel and a vowel.

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 Received Pronunciation or /iə/ and /uə/ in Irish.

Some languages contrast short and long diphthongs, the latter usually being described as having a long first element. 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.

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)

Allophones of the diphthongs /aʊ/ and /aɪ/ in Canadian English (See Canadian raising:

[əʊ] as in house
[əɪ] as in kite

Diphthongs in Australian English phonology:

/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.)
/oɪ/ as in join
/ɪə/ as in fear

Italian

Diphthongs in standard Italian:

falling

/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

/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.

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
/uj/ as in Grenouille

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

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
/eːɐ/ as in der
/iːɐ/ as in dir
/oːɐ/ as in Bor
/øːɐ/ as in Fördern
/uːɐ/ as in nur
/yːɐ/ 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'

Icelandic

Diphthongs in Icelandic are the following:

/aw/ as in já, "yes"
/jɛ/ as in vél, "machine"
/ow/ as in nóg, "enough"
/øɥ/ as in auga, "eye"
/aj/ as in hæ, "hi"
/ej/ as in þeir, "they"

Portuguese

Falling diphthongs with /i/ or /u/ as their weaker vowel are frequent in Portuguese. Rising diphthongs with /i/, /u/, /a/ or /ɐ/ as their weaker vowel occur less often, and are normally analysed as hiatuses. The difference between a rising diphthong and a hiatus is not phonemic; the former are usually found in colloquial speech, and the latter in careful pronunciation. Triphthongs and longer sequences of vowels also occur, but they can be analysed as sequences of vowels and diphthongs. Just like the monophthonghs, diphthongs are divided into two subgroups: oral diphthongs and nasal diphthongs.

Diphthongs in Portuguese:

oral

/ai/ as in pai
/ei/ as in peito
/ɛi/ as in papéis (Brazil)
/oi/ as in coisa
/ɔi/ as in mói
/ui/ as in fui
/au/ as in mau
/eu/ as in seu
/ɛu/ as in céu
/iu/ as in viu
/ou/ as in roupa (parts of Brazil and northern Portugal)

nasal

/ɐ̃ĩ/ as in mãe
/ẽĩ/ as in bem
/õĩ/ as in põe
/ũĩ/ as in muita
/ɐ̃ũ/ as in são

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.

Romanian

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

falling

/aj/ as in mai
/aw/ as in dau
/ej/ as in lei
/ew/ as in leu
/ij/ as in mii (no vocalic glide, but still a diphthong)
/iw/ as in fiu
/oj/ as in goi
/ow/ as in nou
/uj/ as in pui
/əj/ as in răi
/əw/ as in rău
/ɨj/ as in câine
/ɨw/ as in râu

rising

/e̯a/ as in stea
/e̯o/ as in George
/ja/ as in ziar
/je/ as in fier
/jo/ as in chior
/ju/ as in iubit
/o̯a/ as in oameni
/wa/ as in ziua
/wə/ as in două

Spanish

Diphthongs in Spanish:

falling

/ai/ as in hay
/ei/ as in rey
/oi/ as in hoy
/ui/ as in muy
/au/ as in jaula
/eu/ as in feudo

rising

/ja/ as in comedia
/je/ as in tierra
/jo/ as in dio
/ju/ as in ciudad
/wa/ as in guante
/we/ as in fuego
/wi/ as in pingüino
/wo/ as in ambiguo