At 15:31 -0500 14/7/10, Ron Nossaman wrote: >>I'm still curious to know, though, what causes the differences in >>relative volume of this mode according to the position of the fork >>on the board. > >I'd say it's because the pulse is straight along the fork axis. >Touch the side of the handle to the tabletop and the octave volume >diminishes greatly. Yes, but I mean pressing the fork upright on the board at different places on the board results in a different fundamental:octave ratio. This suggests to me that relative admittance of the two frequencies varies. I get similar results whether the board is clamped all round or not. As I said, the relative volume of the fundamental diminishes when three of the boundaries of the board are close to the point of excitation, which might suggest that the waves cannot develop in all directions. Is there an affordable tool to supply powerful vibrations at set frequencies to a soundboard -- the sort of thing they use to demonstrate Chladni patterns? JD
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