Did you know that when you sustain a good strong hum, nitric oxide is produced in the nasal passages.
      This boosts the  immune system and helps manage pain and inflammation.  In the Italian hospital system they use the      technique to help patients with chronic pain conditions.    So when we hum in our choral rehearsals we are supporting our     health!
     (I found this out in my yoga classes., so hum for health, as well as good vocal projection.)