Complex sentence: In phonetics, a vowel is a sound in spoken language, such as an English "ah!" or "oh!", pronounced with an open vocal tract so that there is no build-up of air pressure at any point above the glottis.
Split into simpler sentences: In phonetics, a vowel is a sound in spoken language, such as an English "ah!" or "oh!". In more common phonetic definition, a vowel is a sound pronounced with an open vocal tract so that there is no build-up of air pressure at any point above the glottis.