双元音

双元音（diphthong）是一种复元音（compound vowel），又称双母音或二合复元音，在语音学中，指联合的两个元音，它们作为一个整体出现。之间有平滑的过渡，也就是说，双元音中的发音牵涉到两种不同的舌位，并且从其中一种舌位滑动到另一舌位。在国际音标 (IPA) 中，单元音用一个字母表示，如[ʌ]。双元音用两个字母表示，如[aɪ]，响度较低的字母可以加上  ̯ 符号以表示它是双元音的一部份，例如 [aɪ̯]。

关于拼字时两个一组的元音字母，且通常不分别发成两个元音的情况，请见“二合字母”。

American English pronunciation of no highway cowboys, showing five diphthongs: /oʊ aɪ eɪ aʊ ɔɪ/

双元音的类型

双元音依响度的变化可分为上升双元音与下降双元音（或称上升复元音与下降复元音）。上升复元音以响度较低的元音开始，以响度较高的元音结束，例如 [ɪ̯a]。下降复元音以响度较高的元音开始，以响度较低的元音结束，例如 [aɪ̯]。在某些语言或研究中，会将下降复元音视为真正的双元音，至于上升复元音则倾向于被当作相邻出现的两个元音。例如在汉语中，上升复元音常被当作介音与主要元音的结合，而下降复元音则被当作一个整体的押韵单位。

参见

• 音位变异（英语：Phonemic differentiation）
• 三元音

参考文献

• Birbosa, Plínio A.; Albano, Eleonora C., Brazilian Portuguese, Journal of the International Phonetic Association, 2004, 34 (2): 227–232, doi:10.1017/S0025100304001756
• Bertinetto, Pier Marco; Loporcaro, Michele, The sound pattern of Standard Italian, as compared with the varieties spoken in Florence, Milan and Rome, Journal of the International Phonetic Association, 2005, 35 (2): 131–151, doi:10.1017/S0025100305002148
• Borg, Albert J.; Azzopardi-Alexander, Marie, Maltese, Routledge, 1997, ISBN 0-415-02243-6
• Carbonell, Joan F.; Llisterri, Joaquim, Catalan, Journal of the International Phonetic Association, 1992, 22 (1-2): 53–56, doi:10.1017/S0025100300004618
• Chițoran, Ioana, The Phonology of Romanian: A Constraint-based Approach, Berlin & New York: Mouton de Gruyter, 2001, ISBN 3-11-016766-2
• Chițoran, Ioana, A perception-production study of Romanian diphthongs and glide-vowel sequences, Journal of the International Phonetic Association, 2002a, 32 (2): 203–222, doi:10.1017/S0025100302001044
• Chițoran, Ioana, The phonology and morphology of Romanian diphthongization, Probus, 2002b, 14 (2): 205–246, doi:10.1515/prbs.2002.009
• Cruz-Ferreira, Madalena, European Portuguese, Journal of the International Phonetic Association, 1995, 25 (2): 90–94, doi:10.1017/S0025100300005223
• Faria, Arlo, Applied Phonetics: Portuguese Text-to-Speech, University of California, Berkeley, 2003, CiteSeerX: 10.1.1.134.8785
• Gussenhoven, Carlos, Dutch, Journal of the International Phonetic Association, 1992, 22 (2): 45–47, doi:10.1017/S002510030000459X
• Kaye, Jonathan; Lowenstamm, Jean, De la syllabicité, Dell, François; Vergnaud, Jean-Roger; Hirst, Daniel (编), La forme sonore du langage, Paris: Hermann: 123–159, 1984 [2016-10-22], （原始内容存档于2014-01-07）
• Kleine, Ane, Standard Yiddish, Journal of the International Phonetic Association, 2003, 33 (2): 261–265, doi:10.1017/S0025100303001385
• Kohler, Klaus J., German, Handbook of the International Phonetic Association: A guide to the use of the International Phonetic Alphabet, Cambridge: Cambridge University Press: 86–89, 1999, ISBN 0-521-65236-7, doi:10.1017/S0025100300004874
• Krech, Eva Maria; Stötzer, Ursula, Großes Wörterbuch der deutschen Aussprache, Leipzig: VEB Bibliographisches Institut, 1982, ISBN 978-3323001404
• Martínez-Celdrán, Eugenio; Fernández-Planas, Ana Ma.; Carrera-Sabaté, Josefina, Castilian Spanish, Journal of the International Phonetic Association, 2003, 33 (2): 255–259, doi:10.1017/S0025100303001373
• Mangold, Max. Das Aussprachewörterbuch 3rd. Dudenverlag. 1990. ISBN 3-411-20916-X （德语）.
• Mascaró, Joan, Catalan Phonology and the Phonological Cycle (Doctoral thesis), Massachusetts Institute of Technology, 1976 [12 December 2013], （原始内容存档于2014-01-07）
• Meinhold, Gottfried; Stock, Eberhard, Phonologie der deutschen Gegenwartssprache, Lepzig: VEB Bibliographisches Institut, 1980
• Peters, Jörg, The Flemish–Brabant dialect of Orsmaal–Gussenhoven, Journal of the International Phonetic Association, 2010, 40 (2): 239–246, doi:10.1017/S0025100310000083
• Roach, Peter, British English: Received Pronunciation, Journal of the International Phonetic Association, 2004, 34 (2): 239–245, doi:10.1017/S0025100304001768
• Padgett, Jaye, Glides, Vowels, and Features, Lingua, 2007, 118 (12): 1937–1955, doi:10.1016/j.lingua.2007.10.002
• Schane, Sanford, Diphthongization in Particle Phonology, Goldsmith, John A. (编), The Handbook of Phonological Theory, Blackwell Handbooks in Linguistics, Blackwell: 586–608, 1995
• Tingsabadh, M.R. Kalaya; Abramson, Arthur, Thai, Journal of the International Phonetic Association, 1993, 23 (1): 24–28, doi:10.1017/S0025100300004746
• Tröster-Mutz, Stefan, Variation of vowel length in German (PDF), Groningen, 2011 [2016-10-22], （原始内容存档 (PDF)于2016-03-04）
• Verhoeven, Jo, Belgian Standard Dutch, Journal of the International Phonetic Association, 2005, 35 (2): 243–247 [12 December 2013], doi:10.1017/S0025100305002173, （原始内容存档于2013-12-16）
• Verhoeven, Jo, The Belgian Limburg dialect of Hamont, Journal of the International Phonetic Association, 2007, 37 (2): 219–225, doi:10.1017/S0025100307002940
• Verhoeven, Jo; Van Bael, C., Akoestische kenmerken van de Nederlandse klinkers in drie Vlaamse regio’s, Taal en Tongval, 2002, 54: 1–23
• Wiese, Richard, The Phonology of German, Oxford: Oxford University Press, 1996, ISBN 0-19-824040-6