Sound waves(The behavior of soundboards)

[John Delacour]

At 1:38 PM -0800 12/18/01, Brian Trout wrote:

>A practical example of whether or not the above
>mentioned "phasing" matters is the situation we
>see on a routine basis with unlevel strings.
>When the strings of a unison are out of level and
>the hammer strikes them at slightly different
>times, you have a phasing effect which may not be
>terribly dissimilar to what you describe above.
>It is considered by most to be quite undesirable
>and even an untrained ear can often hear the
>improvment in the tonal characteristics of the
>sound produced by strings closer to vibrating in
>phase with each other (level).
>
>No offense intended.

None taken; but the case you mention is a particular instance which 
involves a number of complicating factors, and the unpleasant effect 
you mention is due to a difference in the nature of the transverse 
vibrations of the two strings.  In the ideal case I am talking about, 
both strings are executing precisely the same wave pattern.  The only 
point I am making is that according to the "bridge moves soundboard" 
theory, if there is a zero force acting vertically upon the bridge, 
as will occur frequently, the result will be no movement of the 
bridge and soundboard and therefore virtually no sound.  Since I 
reject the theory, I say that this silence never actually happens.

JD