Diphthongs

The vowels so far are monophthongs: they are ‘pure’ and do not change. Diphthongs are monosyllabic vowels which have two discernibly different points, one at the start and one at the end. Most varieties of English have several diphthongs. The most obvious diphthongs are the vowels of CHOICE, MOUTH and PRICE in most standard varieties of English. These diphthongs start with open vowels and then raise to close vowels, generally in the area of [i] or [u]. These are called closing diphthongs for this reason. Diphthongs are transcribed by the start and end points. E.g. the vowel of choice is transcribed in RP as  : it starts with [ɔ] and ends with [I].