In phonetics, vowel height is the position of the tongue relative to the back of the mouth in a vowel sound. The second formant of a vowel (F2) usually corresponds to vowel height, with a lower F2 corresponding to a back vowel and a higher F2 corresponding to a front vowel.
The International Phonetic Alphabet identifies 5 different degrees of vowel backness, although no known language distinguishes all 5:
