Triphthong

In phonetics, a triphthong /ˈtrɪfθɒŋ/ (from Greek τρίφθογγος, "triphthongos", literally "with three sounds," or "with three tones") is a monosyllabic vowel combination involving a quick but smooth movement of the articulator from one vowel quality to another that passes over a third. While "pure" vowels, or monophthongs, are said to have one target articulator position, diphthongs have two, and triphthongs three.

Examples

First segment is the nucleus

English in British Received Pronunciation (monosyllabic triphthongs with R are optionally distinguished from sequences with disyllabic realizations)

• [aʊ̯ə̯] as in hour (compare with disyllabic "shower" [aʊ̯.ə])
• [aɪ̯ə̯] as in fire (compare with disyllabic "higher" [aɪ̯.ə])
• [ɔɪ̯ə̯] as in "loir" (compare with final disyllabic sequence in "employer" [ɔɪ̯.ə])

As [eɪ̯] and [əʊ̯] become [ɛə̯] and [ɔː] respectively before /r/, all instances of [eɪ̯.ə] and [əʊ̯.ə] are words with the suffix "-er".
Bernese German (a Swiss German dialect):

• [iə̯u̯] as in Gieu 'boy'
• [yə̯u̯] as in Gfüeu 'feeling'
• [uə̯u̯] as in Schueu 'school'
• [yə̯i̯] as in Müej 'trouble'

Northern Austro-Bavarian:^[1]

• [ɔu̯ɐ̯] as in /hɔu̯ɐ̯/ (MHG hâr) 'hair', or as in /ɔu̯ɐ̯/ (mhd. ôr) 'ear'
• [ɛi̯ə̯] as in /mɛi̯ə̯/ (MHG mêr) 'more'
• [ou̯ɐ̯] as in /ʃnou̯ɐ̯/ (MHG snuor) 'cord'
• [ei̯ə̯] as in /fei̯ə̯/ (MHG vier) 'four', or as in /ʃnei̯ə̯l/ (MHG snüerelîn) 'small cord'

The Northern Austro-Bavarian triphthongs have evolved from combinations of former long vowels or diphthongs from the Middle High German (MHG) period and vocalized r.

Second segment is the nucleus

Portuguese:

• [u̯ai̯] as in Paraguai 'Paraguay', iguais 'equal, similar, same (plural)', and quaisquer 'any (plural)'
• [u̯ei̯ ~ u̯ɐi̯] as in enxaguei 'I did rinsed' and magoei 'I get/did (emotional) hurt'
• [u̯ɐ̃u̯] as in saguão 'crush-room'
• [u̯ẽi̯ ~ u̯ɐ̃i̯] as in delinquem 'they break the law' and enxaguem 'they rinse'

Some Portuguese triphthongs appears in places where some speakers can break the first segment to form a hiatus (that is, [i̯] or [u̯] are not equivalent to standard Portuguese semivowels [j] and [w] in this case), and as such they are deemed as non-triphthongs by standard, although many or most speakers produce them as such (and even more frequently when speaking colloquially):

• [i̯ei̯ ~ i̯ɐi̯] as in mapeei 'I mapped' and maquiei 'I did make up' or (colloquially) 'I disguised (the reality)'
• [i̯ou̯] as in clareou 'cleared (singular third person)', miou 'meowed' (second and third persons singular) and piou 'chirped' (singular second and third persons)

In addition, phonetic diphthongs are formed in most Brazilian Portuguese dialects by the vocalization of /l/ in the syllable coda, as well as by yodization of vowels preceding /s/ and /z/ or their syllable-final pre-consonantal allophones [ʃ] and [ʒ], thus if these consonants precede diphthongs, it is likely that a triphthong will form:

• [u̯] for alluvial 'alluvial' ([i̯au̯], manual 'manual' ([u̯au̯]) and Gabriel 'Gabriel' ([i̯ɛu̯])
• [i̯] for aloés 'aloe plants' (u̯ɛi̯) and águias 'eagles' ([i̯ai̯)

Romanian:

• [i̯au̯] as in iau 'I take'
• [e̯au̯] as in rîdeau 'they were laughing'

Spanish:

• [u̯ei̯] as in buey 'ox'
• [u̯ai̯] as in Uruguay
• [i̯ai̯] as in cambiáis ('you [plural]change')
• [i̯ei̯] as in cambiéis ('that you may change')

Vietnamese:

• [ɨ̯əɪ̯] as in tươi 'fresh'
• [ɨ̯əʊ̯] as in rượu 'alcohol'
• [i̯əʊ̯] as in tiêu 'pepper'
• [u̯əɪ̯] as in nuôi 'to nourish'
• [u̯ai̯] as in khoai 'potato'
• [u̯iɜ] as in khuya 'late into the night'
• [u̯iʊ̯] as in khuỵu 'to fall on one's knees'^{[citation needed]}
• [u̯ɛʊ̯] as in ngoẹo 'to turn/twist'

Third segment is the nucleus

Romanian (semivocalic phonemes marked with inverted breve accent below):

• [e̯o̯a] as in pleoape 'eyelids'
• [i̯o̯a] as in creioane 'pencils'

References

Gütter, Adolf (1971). Nordbairischer Sprachatlas. pp. maps 8 mhd. â, 9 mhd. ô, 11 mhd. ê, 15 mhd. uo, 13 mhd. ie, 14 mhd. üe.

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