Sound Propagation

[John Delacour]

At 9:16 PM +0100 1/8/02, Richard Brekne wrote:

>This is still in the opening chapters of his book and I still don't 
>have anything to couple this kind of wave propagation directly to 
>the sound board. But if vibration energy has to propagate in similar 
>fashion for all elastic medium...then ...well I am still pointed in 
>that direction. In any case it was neat to see that my thinking 
>along the pond / ripple tangent wasn't completely out in left field. 
>:)

Richard, so long as you go on thinking of waves in ponds and lakes 
and troughs, this discussion will again be drowned in a sea of 
irrelevancies.

The soundboard+ is a solid system with clamped edges.  In so far as 
it exhibits any flexural vibrations, those vibrations will be at the 
natural frequencies of the board and may or may not have some slight 
influence or complicating effect on the propagation and radiation of 
the sound from the strings, but as a complication I'd say it ranks 
exceedingly low among a host of more important complications.  The 
main function of the soundboard is to propagate sound through its own 
anisotropic substance and to radiate acoustic energy at its surface. 
A soundboard is neither a thin pond nor a membrane nor a blanket nor 
a clothes-line.

Have a good look through the definitions at
<http://www.sfu.ca/sonic-studio/handbook/>


and if you want to see some sigmas and deltas, go to:
<http://www.du.edu/~jcalvert/waves/wavhom.htm#index>

The only transverse vibration that is at all relevant is that of the 
string, and since the source of the sound is at the termination of 
the string, even that is not really under consideration.

JD