Comment: Resonance adjustment conditioned by the vowel. Changing vowels on a single tone.

Quote:  ...control over the resonance adjustment through its correlative association with the vowel becomes a consideration of major importance. ...The intent here [singing different vowel sounds on a single tone] should be to have each successive vowel flow logically out of the position formed by its predecessor while maintaining a solid underscoring of the basic resonance. (The Free Voice)