Diphthong

A diphthong (/ˈdɪfθɒŋg/) or double vowel sound is a vowel sound, contained within one syllable, that has consists of two different vowel positions; a starting position and a finish position. There are two main kinds in English; rising diphthongs and falling diphthongs.

Falling diphthong

A falling diphthong starts with a vowel of higher prominence and ends with a short vowel [ɪ], [ʊ], [ə] or semivowel [j] or [w]. In English it is customary to use vowels (e.g. [ɪ] instead of [j]), and to consider falling diphthongs as phonemes.

• IPA phoneme /eɪ/: face, play
• IPA phoneme /ɔɪ/: choice, boy
• IPA phoneme /aʊ/: mouth, how
• IPA phoneme /aɪ/: price, fly
• IPA phoneme /əʊ/: goat, so
• IPA phoneme /eə/: square
• IPA phoneme /ʊə/: cure
• IPA phoneme /ɪə/: near

Some phoneticians consider that /iː/ is a diphthong [ij] and that /uː/ is a diphthong [uw].

Rising diphthong

A rising diphthong begins with a semivowel [j] or [w]. In English rising diphthongs are normally analyzed as sequences of two phonemes. There are many rising diphthongs in English, as /j/ and /w/ can combine with many vowels.

• IPA phonetic sequence /juː/: cute, few
• /jɒ/: yacht
• /je/: yell
• /jə/: Kenya
• /wiː/: weed
• /wɪ/: quick
• /wɔː/: walk