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Looper's Delight
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Lindsay, Sound is not 'moving air'. Sound is compression and rarefaction of air. The difficulty with creating low frequency sound in air is not that you have to 'move' the air, but that you have to 'compress' and 'decompress (rarefact)' the air, at a given frequency. This is difficult because of the impedance mismatch between a vibrating object (say a raw unmounted speaker cone) and the air. That is, they do not couple well (it is an inefficient transfer of mechanical movement to compression of air). Speaker box design helps to 'couple' the speaker to the air so that the speaker cone movement 'compresses' the air. Horn speakers are the highest efficiency because they assist in coupling the air to the driver movement. The horn diaphragm can be small, but if the horn couples the diaphragm to the air well it can create high spl at low frequencies (with small movement of the cone, ala Klipsch). This conversion is more efficient in a horn speaker than a raw speaker. These pressure waves in air (we call sound) radiate like the waves created in a pond when a rock is dropped into still water. In water the waves radiate as a widening circle around the point of origin (until disturbed by objects in the water, or until they dissipate all their energy). In air, sound pressure waves radiate and expand outwardly in spheres of compression and rarefaction radiating from the point of origin (until disturbed by objects, or until they dissipate all their energy). A bowl 20" wide has a circumference of about 62.8". I don't know how high your bowl is, but let's say it is 4" high, and let's say it is a cylinder shape. So, the surface area of this bowl is about 251 square inches. A 15" Loudspeaker has less than 176 square inches. So, the surface area of a 20" bowl is greater than that of a 15" Loudspeaker. I can feel the intense, low freq vibration of these bowls in my hands, much like I feel the intense vibration of my 15" bass speaker, and like I feel the intense low freq vibration in gongs that I have. These gongs are only about 12" in diameter (about 113 square inches of area). These small gongs generate a VERY LARGE, LOUD, LOW Freq sound that I both hear and FEEL with my skin. The singing bowls radiating surface is shaped in a cylinder, or in rounded bowls somewhat spherical (excluding the top and bottom of the bowl). This would assist the bowl in efficiently radiating the spheres of compression and rarefaction we call sound. With an oscilloscope I will measure the low frequency generated by my small bowl (~6" diameter) to see if my assertion is correct (that the bowls truly do generate these low fundamentals that we hear). bret --- lindsay@pavestone.com wrote: > > >I just dont understand why bowls should not vibrate them? > > Yes, the tones are too low for the bowl to physically produce them. > If you > think about it, bass notes are pretty darn large airwaves and > therefore > require pretty darn large instruments to produce them. At 20Hz, the > wavelength is 56 feet long. There's just no way a bowl 20" wide > weighing > eight pounds can move that much air with enough energy to produce the > tone. > Imagine how much more difficult it is to move 56 feet of air than, > say, a > mere 2.47 feet for a 440Hz A note. > __________________________________________________ Do You Yahoo!? Yahoo! Messenger - Talk while you surf! It's FREE. http://im.yahoo.com/