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Hi Bret: Just wanted to let you know, that was a great reply! Clear, straightforward...what can we say? Your explanation of the link between sound and air moved us! Best, Roctologists aka LoOpdOctOrs on 10/18/00 9:13 PM, Bret at echoplex@yahoo.com wrote: > 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/ >