| The relative backness of the two vowels was opposite in the two areas that distinguished them. |
| Rounding is generally realized by a decrease of F2 that tends to reinforce vowel backness. |
| In a similar fashion, the horizontal axis of the chart is determined by vowel backness. |
| Vowel backness is named for the position of the tongue during the articulation of a vowel relative to the back of the mouth. |
| Although English contrasts six heights in its vowels, they are interdependent with differences in backness, and many are parts of diphthongs. |
| Umlaut or mutation is an assimilatory process acting on vowels preceding a vowel or semivowel of a different vowel backness. |
