A singing bowl is a bell turned upside down: a bowl that rings when you strike its rim with a mallet, and sings a steady tone when you rub a stick around it.
Striking sets the wall vibrating in several ways at once, each with its own pitch. A bowl is never perfectly round or evenly thick, so each of those pitches splits into two that are very slightly apart, and the two interfere. You hear that as a slow pulse, the beating that gives a good bowl its shimmer.
Rubbing the rim with a wooden or leather-wrapped stick works like a bow on a violin string. The stick grips and slips thousands of times a second and feeds energy into the ringing, so the tone swells and then holds for as long as you keep moving.
Bowls like these are made and sold across the Himalayas, in Tibet, Nepal, Bhutan and northern India. They are often described as ancient, cast from a sacred alloy of seven metals, and used for healing for thousands of years. The evidence is thinner than the legend: most bowls are copper-tin bronze, and the early history of bowls used for meditation is hard to document. What is clear is that they reached the West in large numbers from the 1970s onward, through the meditation and New Age scenes.
In a sound bath, people lie down and listen while a practitioner plays bowls, gongs or chimes. Many report feeling calm and relaxed, and small studies suggest short-term drops in tension and improved mood. There is no good evidence that it treats medical conditions, so it is best taken as a way to rest and to listen.
The bowls here are not recordings. Each one is synthesized in your browser with the beating overtones described above, so it works offline.