Tibetan Singing Bowls are actually in fact classified as bells and so would be discussed in the western world a percussion instrument: a pitched percussion instrument and unpitched depending on use and effect. Usually a bronze alloy, these bells are not hung but are free standing in nature, often place on a flat surface or in the hand. In most music we think of bells as being struck, bells clanging out from the tops of churches. But the makeup of a bell is one that is obviously conducive to more than one way in which to vibrate and create energy.
A singing bowl (tibetan singing bowl included) is a special type of bell in that you do necessary strike (though it is just as often struck as well as “sung”) it as you would a bell in a clock tower, but instead is made to “sing” by slowly enhancing the bells natural vibrations to ring out a tone. How is this done? What does it look like? Well the simplest analogy is one that I find around Thanksgiving time: using your finger to rub the lip of a wine glass to produce a ringing tone. I believe we have all been there rubbing our finger around the crystal, different amounts of water changing the vibration to change the tone.
Tibetan bowls work similarly if not almost exactly like our crystal glasses. Usually a stick of sorts (instead or a finger) is used and rubbed around the lip of the bowl. This rubbing causes friction and friction is energy, or waves. As the energy is applied in a circular motion the entire bowl literally starts to vibrate. This vibration reaches a point where it becomes an audible tone. The bowl emits this energy and tone and we hear a “singing sound.”
The tone produced sounds similar to the way it is made. It is not a loud or sudden sound but a sound that seems to grow as the rubbing of the top of the bowl goes on and on. The tone seems to swell and diminish calmly reflecting the musician or person who is actually using the bow. Soft and steady produces a soft and steady tone, where quicker rotations increase the energy and changes the sound. But that is not to say that these bowls are not used as sounding devices or struck as well. Many times, depending the desired results you can intermittently switch between the ringing sound and the struck bell sound.
One typical way the striking sound of a bronze bowl is used is in meditation and meditation ritual. The bowls shape themselves lend to a very unique sound as they are more often than not round in shape and not “bell” shaped like we may be used to. Just like the shape of an instrument changes the sound produced we can find the same quality with singing bowls. There are phone applications that use different bowl sounds as meditation timers. This is a very gentle way to come in and out of your meditative states. For ritual you can you the clang of a singing bowl to signify the beginning of supper or a particular event in a day.