If you grip Tibetan Singing Bowls in your grip, it is free to vibrate. Then, you can softly slide a mallet across the side of it. This is what generates the singing sensation, often used for Tibetan meditation. You can also quietly tap the side of the bowl. This generates a bell-like noise. Either way you use crystal singing bowls, it is the vibrations that create the sound, similar to if you press and slide your finger around the edge of a champagne glass. The pitch of the sound can vary depending on the bowl density. Bowls can be as wide as 4 to eleven inches. You can also increase the mallet speed to modify the sound.