Backness
Vowel backness is named for the position of the tongue during the articulation of a vowel relative to the back of the mouth. In front vowels, such as, the tongue is positioned forward in the mouth, whereas in back vowels, such as, the tongue is positioned towards the back of the mouth. However, vowels are defined as back or front not according to actual articulation, but according to the relative frequency of the second formant (F2). The higher the F2 value, the fronter the vowel; the lower the F2 value, the more retracted the vowel.
The International Phonetic Alphabet identifies five different degrees of vowel backness:
- front vowel
- near-front vowel
- central vowel
- near-back vowel
- back vowel
Although English has vowels at all five degrees of backness, there is no known language that distinguishes all five without additional differences in height or rounding.
Read more about this topic: Vowel, Articulation