This step in the Advanced Warm-up Series works on taking your voice from the middle of your range and expanding upward. If you want a well-rounded voice warm-up, you might want to add Exploring Lower Range to your warm-up prep. Begin by being very relaxed, and stand tall with your shoulders wide, your weight spread evenly over the balls of your feet and your heels. Breathe to your core, and then explore…
I'd like you to play with your voice in this step, and use the upper (falsetto, for men) range, where the sound vibrates in your head. The sound you will make is similar to the sound of the coyote falling off a cliff in the old Road Runner cartoons, like this. [Note that this sound is only an example — it's not meant as a model for you to copy.] Start fairly high up, so that you're in your head voice/falsetto, and slowly start to slide down on an "EE" (IPA [i] ) vowel. I can't stress enough how important it is to go slowly through your voice, and that, if your voice is prone to "cracking" as you shift registers, you should slow down as you approach those areas of your range. When you run out of breath, stop the tone, breathe down into your core, and continue the slide downward from the pitch where you left off. If you can, try to stay in your head tone/falsetto; don't switch into chest resonance. You'll get into a place in your voice that is not very effective for speaking, one that sounds rather odd and breathy, and your voice will want to switch into chest tone. Don't let it!
After one downward slide, you'll want to do another one, starting one note higher up that the previous slide. Continue to slide down through your range, working up higher and higher, note by note. Always remember to breathe when you need to, to go very slowly, and never to lift your chin or head as you "reach" for the next note in the sequence.
Resonance-wise, you should be feeling buzziness in your head and in your face, and your goal is to enhance that feeling as best you can. Experiment with your tongue placement so that your head buzzes as much as possible.
Next Step: Head-Jaw Relationship