Singing bowls produce sounds which invoke a deep state of relaxation which naturally assist one in entering into meditation, the ultimate goal being enlightenment (samadhi).
They are a quintessential aid to meditation, and can be found on private Buddhist altars, and in temples, monasteries and meditation halls throughout the world... and now also on my mantel.
Playing the bells usually causes an immediate centering effect. The tones set up a "frequency following response" that creates a balancing left/right brain synchronization. Meditating on the subtle sounds of the Tibetan singing bowl tunes one in to the universal sound within and without.
If you've come to a yin or restorative class of mine lately, then you'll definitely have heard this played before - whether you've noticed it or not!