Excellent ways to gently warm up the voice are lip trills and humming. Lip trills provide relaxation in the facial muscles and energize the breath. It is important to keep the lips slightly pressed together. If there is too much space, breath will escape. When the coordination is correct at the lips, add sound and continue trilling to exercise the entire vocal range. Humming sets the tone with balanced resonance. The lips should be relaxed and gently pressed together, the teeth should be slightly apart, and the soft palate lifted. Both exercises are best used with light vocal weight and concentration on focusing the voice.
Sep 16