A colleague recently told me about a sound exercise that our teacher loves, which involves an etude with a lot of intervals and octave changes. She suggests moving everything into the comfortable middle register and practicing with the goal of staying open.
I did this several days ago, and remembered what it felt like to just breathe and let sound happen. I wasn't forcing anything into place, just exhaling. (With a flute on my face.) I allowed air in my cheeks, and I felt resonance happen, instead of trying to make it happen.
I found it easiest to achieve this open feeling when I left the tongue out entirely. I simply let the air start the sound. I also stopped worrying about where my lips should go or if my tongue was tense or in the way.
I was so thrilled with my sound, I immediately tore my bookshelves apart looking for more and more things to play! (I'm supposed to be packing to leave for the summer...) It became fun to play everything with this exact same open feeling. I've been trying to overcome my habits of making micro-adjustments from note to note, and in doing so have added some unnecessary panic and therefore tension.
Pretending that EVERY note was the same as an easy-breezy middle C did the trick! Whenever I felt my throat begin to tense, I just played middle C again and memorized the feeling.
The feeling of support that accompanies this is the natural exhale, which provides an easy, constant airstream. One of my favorite exercises is from David Vining's Breathing Book.
Watch his video demonstration here:
I played through two whole books of etudes, and realized (for the hundredth time) that sound is the most important part of practicing technique. It's really about finding the most ideal "tone set-up," and inhibiting habits that could disrupt it. Somehow, it becomes easier to move fingers faster and more evenly when you are able to trust and stay open.