Singing bowl

Two families are in common use. Metal bowls are hand-hammered alloys, traditionally made across the Himalayan region, and their irregular walls produce a dense cluster of tones. Crystal bowls are machined from fused quartz and sound purer, brighter and narrower. Either can be struck with a felt mallet for a clear tone that fades over twenty or thirty seconds, or rimmed — the mallet dragged around the edge — which feeds the sound continuously for as long as the arm holds out.

What they are for is sustaining a sound long enough for the body to settle under it. The physics is ordinary and interesting: a bowl produces a fundamental plus partials that are not neat multiples of it, and when two partials sit a few hertz apart you hear one tone pulsing slowly. That slow beating is what almost everyone describes as waves. A large bowl also moves enough air to be felt on the skin and through bone, most often in the sternum.

In a KEO session Ben plays a mixed set — several hammered bowls, two crystal bowls, a gong, and tingsha cymbals. In a yoga class the bowls arrive for the last ten to fifteen minutes, once everyone is already lying down. In a full sound session some bowls may be placed on or beside the body, which makes the vibration unmistakable, and that placement is always offered rather than assumed.