Articulatory classification of English vowels
Vowels unlike consonants are produced with no obstruction to the stream of air, so on the perception level their integral characteristic is naturally tone, not noise. The following 20 vowel phonemes are distinguished in BBC English: [i:, a:, ɔ:, u:, з:, ı, e, æ, ɔ, υ, ʌ, ə; eı, aı, ɔı, аυ, ou, eǝ, υə, ıə].