Diftong (grčkidi-, phthongos- glas) je dvoglasnik, tj. dva razna samoglasnika koji su spojeni u jedan slog (npr. ao, eo, io) itd.
Literatura
Barbosa, Plínio A. & Albano, Eleonora C. (2004), "Brazilian Portuguese", Journal of the International Phonetic Association 34(2): 227-232
Cruz-Ferreira, Madalena (1995), "European Portuguese", Journal of the International Phonetic Association 25(2): 90-94
Gussenhoven, Carlos (1992), "Dutch", Journal of the International Phonetic Association 22(2): 45-47
Martínez-Celdrán, Eugenio; Fernández-Planas, Ana Ma. & Carrera-Sabaté, Josefina (2003), "Castilian Spanish", Journal of the International Phonetic Association 33(2): 255-259
Roach, Peter (2004), "British English: Received Pronunciation", Journal of the International Phonetic Association 34(2): 239-245
Verhoeven, Jo (2005), "Belgian Standard Dutch", Journal of the International Phonetic Association 25(2): 243-247
Verhoeven, Jo (2007), "The Belgian Limburg dialect of Hamont", Journal of the International Phonetic Association 27(2): 219-225
Verhoeven, Jo & Van Bael, C. (2002), "Akoestische kenmerken van de Nederlandse klinkers in drie Vlaamse regio’s", Taal en Tongval 54: 1-23