Sound waves(The behavior of soundboards)

[John Delacour]

At 12:31 AM -0600 1/22/02, Ron Nossaman wrote:

>I seem to have failed in detecting the critical point in Anders' message
>supporting your insistence that the string doesn't directly move the bridge

On 1/21/02, Anders Askenfelt wrote:
>1. The force from the string tries to drive the soundboard up and down mainly.

Has it occurred to you why he says "tries to drive" ?  If it 
succeeds, why doesn't he just write "drives..." or "directly 
drives...", and if it succeeds, what earthly cause or need is there 
for the bending waves?

>and that the soundboard moves before the bridge.

At 10:22 PM +0000 12/24/01, John Delacour wrote:
>For the moment I will willingly concede that my hypothesis that the 
>bridge moves "after the soundboard" in these rocking or vertical or 
>any other movement, because it has never actually been a big issue. 
>The answer to this question may turn up later.  So you can no longer 
>use this as a smokescreen.

Here's a "neat little experiment", as the fashion is, quoted from the 
first chapter Lord Rayleigh's "Theory of Sound" (quite a pretty 
little tome of some renoun):

>7. The conveyance of sound by solids may be illustrated by a pretty 
>experiment due to Wheatstone. One end of a metallic wire is 
>connected with the sound-board of a pianoforte, and the other taken 
>through the partitions or floors into another part of the building, 
>where naturally nothing would be audible. If a resonance-board (such 
>as a violin) be now placed in contact with the wire, a tune played 
>on the piano is easily heard, and the sound seems to emanate from 
>the resonance-board. [Mechanical telephones upon this principle have 
>been introduced into practical use for the conveyance of speech.]

Now I suppose you are going to tell me that the sound-board of the 
pianoforte moves the wire threaded through the building and the wire 
threaded through the building moves the resonance-board or violin 
plate, and that this it does directly.

I have previously mentioned the cocoa-tin telephones of my childhood 
with no reponse, but you'll probably find Wheatstone and Rayleigh 
less worthy or your contempt.

JD