Vowel sound

From Teflpedia

A vowel sound (/vaʊl saʊnd/) is a speech sound which is pronounced with an open vocal tract so that there is no build-up of air pressure at any point above the glottis.

There are three kinds of vowel sounds: monophthongs, diphthongs and triphthongs.

For historical reasons there is a large mismatch between the number of vowels in English - which has up to twenty vowels (depending on the accent) - and the vowel letters, which are limited to A, E, I, O, U, and letters representing the semi-vowels, Y and W and even R.