Demos: 4B-07 Tibetan Singing Bowls
All sound is vibration, manifested in the form of standing waves. Sound also requires matter to pass through, which is why there is no sound in outer space. The sound of a Tibetan Singing Bowl is created by the vibration of the metal. The method is similar to that of playing a crystal glass by running a finger along the rim. The vibration is caused by your finger slipping and sticking to the rim of the glass. Only with the Singing Bowl, it is a dry wooden mallet. Water on the rim will interfere too much, and is not recommended. The bowl shape acts as an excellent resonating chamber, giving the sound a place to "echo" and giving it the characteristic rich tones.
Manual (PDF)