Humming is good too. Generates NO bubbles. You know, the Ohmmmm
  sound? The humming. It's the same magic that's in nitroglycerine
  pills to jumpstart your heart, what CoQ10 makes for you, what's
  in Viagra... same little bubbles... helps form memories in the
  brain. I did research on it a couple of years ago. Little
  bubbles. So, yeah - the omm thing has definite tangibles.