Antique singing bowls make a unique sound that is not like any other instrument in the world. The bowl shape, material used, construction methods and age all play a factor in the sound of an antique singing bowl.
Singing bowls produce several frequencies all at once. We can hear 3 or 4 of the frequencies. The lowest audible tone is known as the fundamental tone, or first harmonic. This is the main note of the bowl. The pitch of the fundamental note varies according to the size and thickness of the bowl as well as tension at the rim.
The second harmonic is the next audible tone, which is a harmonic overtone higher than the fundamental. It is the mid pitch and usually 4 notes above the fundamental. So, if a bowl has a fundamental tone of A, the second harmonic is likely to be an D.
The third harmonic is usually 4 notes higher than the second, or one octave above the fundamental. A perfectly tuned A bowl will have a third harmonic also A.
Some bowls you can hear a fourth pitch, very high. This happens when the bowl starts very deep and the fourth harmonic is still within audible range. Higher pitched bowls also produce a fourth harmonic, we just can't hear it.
Some people refer to a "struck tone" and a "rim tone." This is somewhat confusing because singing bowls only produce the three tones mentioned. When struck with a soft mallet, like the recordings I provide, you can hear all three audible tones at once. Listen carefully with headphones and see if you can pick them out.
The "rim tone" is what you hear when you play the bowl around the rim. It produces the same exact pitches, only you may hear them slightly differently.
When playing around the rim, the second or third harmonic is usually emphasized. Most bowls will resolve to playing the mid tone around the rim. The other tones become quieter.
You can change the angle, speed and material of your mallet to bring out the other tones while playing around the rim. A leather mallet tends to emphasize the low tone. A thinner mallet will emphasize the high harmonic. The same tones are played, but you can emphasize one or the other depending on how you play it.
I always record the struck tone so you hear the combination of the pitches and the real length of the tone. Singing bowls are traditionally struck and sound the best this way.
All singing bowls can also be played around the rim and it is the same pitch as the struck tone. The only variation in pitch of any singing bowl is from what I call pitch shift. The pitch of the bowl can change up to half a step depending on where you play it. Strike the bowl in one place, the pitch may be slightly lower. Turn the bowl and strike it in another place, the pitch may be slightly higher. It is a subtle shift but can make a difference if you are using them for music or want a precise pitch for another reason.
Generally, the thicker the bowl and the more pronounced rim it has, the less pitch shift will occur. Thinner bowls tend to have larger pitch shift.
Another thing that is affected by how you play the bowl is the warble, or the wah-wah sounds of the bowl. Each of the three pitches can play with warble or without warble. Strike the bowl in one place, you will hear the low tone warble and the mid harmonic more steady. Turn the bowl and strike it again, the low tone may be steady and one of the harmonics warbling.
There is a lot of variation in this phenomenon but generally speaking, when the low tone is steady, one of the harmonics will warble and when the harmonics are steady, the low tone will likely warble. Some bowls always warble. You cannot get any steady tone. Other bowls are very steady and you do not hear much warble.
Many bowls have what I call the "sweet spot," where the tone is very steady and strong. Another interesting phenomenon about warble is that when there is more warble, the tone tends to ring longer. The same bowl played in the steady sweet spot will ring slightly shorter than when allowed to warble. It is as if the energy of the warble keeps the metal moving.
Warble is caused by the physical energy of the bowl pulsing in and out. The metal pulses and a wave of energy goes around the rim. If you imagine this movement over time, the energy moving around the bowl and in and out creates a three dimensional spiraling wave.
The energy from a bowl fills the room, moving outward from the middle. I have place a microphone in the exact middle of a singing bowl. No sound is picked up this way. The exact middle of a singing bowl is completely calm, as all the sound energy moves outward.
The shape of a bowl determines the quality of the tone. A taller bowl produces more echo. A short sided bowl produces less echo and sounds more bell like. While the overall size of the bowl is important, the thickness of a bowl is what determines the pitch. If you take two of the same sized bowls, the thicker one will be higher pitched. Thinner bowls sound deeper.
Likewise, the tension formed at the rim determines the pitch. A shaped rim with a lot of tension is higher pitched. A bowl with no rim is lower pitched.
The ideal thickness for a singing bowl is medium thick, about 1/8 of an inch, less than half of a centimeter. Medium thick singing bowls ring longer and more true than either thicker or thinner bowls. Of course, there are always exceptions.
Antique singing bowls ring on average about 30 seconds. The bowls in The Singing Bowl Museum collection mostly ring longer than a minute. The length of tone is a function of several factors, including the shape and thickness. It seems the overall tension of the metal determines the length of tone. Some antique singing bowls ring for nearly 3 minutes.
Antique singing bowls are made from bell metal bronze, 77-78% copper and 22-23% tin. New hand hammered singing bowls are still made of the same alloy and produce a similar sound. However, most singing bowls are made from brass and sound very different. They lack the multiple tones and beauty of bronze singing bowls. Singing bowls do not sound the same when made of different metal.
Only the traditional alloy has the authentic beautiful sound. The age of a singing bowl is a significant factor in its tone. New bronze singing bowls are the closest to the antiques. The new versions are louder, often ring longer but lack the warmth and beauty of the real antiques.
As the metal ages, it changes. The tone becomes mellow and less metallic. As singing bowls age, they take on a warm and relaxing quality to which nothing else compares.
No other instrument in the world has the power to relax the body, calm the mind and transform the environment. Antique singing bowls really make a room feel amazing. They have a presence and power that nothing else has.
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