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--- "Ryan D. Supak" <rdsupak@hoover-keith.com> wrote: > i am an acoustics engineer (honest, check hoover-keith.com!) > > firstly, anything can theoretically generate any frequency (e.g. i > can > generate a 10 hz tone by tapping my fingers 10 times per second on a > paper plate.) > > ****ultra-simplified resonance theory**** > > however, any resonating object can only have two of these three > qualities: > 1) small size > 2) high efficiency > 3) large low frequency emission > > thus, a small bowl *can* generate, say, a 35Hz fundamental, albeit > extremely inefficiently (assuming modern materials, 12.5 PSI, sea > level, > typical acoustic space, etc...) Ryan, I basically agree with what you say here. The terms small, high, and large are very general terms, as you said these are simplified principles. I encountered this trade-off between smallness, efficiency, low freq output with the Thiele/Small loudspeaker enclosure design principles. The point is that there are trade-offs between these 3 metrics. In the Thiele/Small world the notions of small, efficient, and low freq output are looked at in a relative, not absolute way. That is, if you have box design of X cubic feet, and you make it smaller, you will diminish one of the other 2 parameters (you will either loose efficiency, or low frequency output, or some of both). So how small a bowl is too small to be (physically) able to create the low freq, loud (vague terms) sound we hear from the bowls, with the amount of energy we apply to the bowls? Is a 15" loudspeaker cone small? The 20" bowls vibrating surface is larger than the speaker size that is commonly used for generating loud, low freq. I have casually mapped the vibrating surface and it seems to be virtually the entire sides of the bowl, down to the start of the base. The bowl is small, but the radiating surface of the bowl seems large to me. But small and large are relative terms, aren't they? Regarding efficiency, I cannot say how efficient the bowls are. As you play them you constantly put energy into them. I make no claims for the bowls efficiency, but they could be inefficient (and per stated principles) and still be loud and low freq. It tires me to play them for very long, but I'm not sure how to quantify the energy I put into the bowl from the playing (how efficient is the energy transfer from my hand to the stick to the bowls edge?). A single strike to the bowl will excite it at the low fundamental, if you hit it in the right area. Anyway, I am very curious about what is happening, and sorry if this thread is wearing thin for some of you. I find the singing bowls fascinating and fun, and it is my nature to try and figure out how things work, especially sound (I too am an engineer, but acoustics are only a part of my job with disk drive design). I'll shut up now, and see what I measure. bret __________________________________________________ Do You Yahoo!? Yahoo! Messenger - Talk while you surf! It's FREE. http://im.yahoo.com/