Sound waves(The behavior of soundboards)

[Richard Brekne]

Ron Nossaman wrote:

> >
> >>
> >> Yet there is no doubt that he attributes the rocking motion to longitudinal
> >> movement in the strings vibration. I doubt seriously he would choose this
> >> word unless he meant to use it.
> >
>
> I have already described the string tension differences across the bridge
> resulting from the excursion of the speaking length. This would qualify as a
> longitudinal force component as far as I am concerned, and has been addressed.
> I don't presume to read Anders' mind. If you want clarification, ask him the
> right question.
>

The longitudinal component refers to exactly that part of the wave
motion on the
string that is longitudinal.  I have difficulty seeing from my present
understanding of what you wrote earlier on relative to string tension
differences across the bridge, that this is the same thing. Tho I will
re-read your earlier comments on tension differences across the bridge
in this light.


> >>
> >>  The point is, no matter how you cut it this is a different kind of force
> >> then the one you applied with your "finger on a string" bit .
> >
>
> It is exactly the same kind of force.

How could a pulse traveling at and appling its force 90 degrees to the
surface of
the bridge exert exactly the same kind of force as what is esentially
someone fastening a
tetter-totter to the whole of the surface of the bridge and rocking up
and down on it ? I dont get it.

> >
> >>
> >> Your finger example was much more analogous of a purely transverse action.
> >> And I think it was the kind of mental picture this purely transverse action
> >> creates that loosed Johns counteraction.
> >
>
> I have already described both the action, and the result, and don't care to
> speculate on what John thought.

You have simply restated your earlier position, with the apparent
clarifification that you now equate this to be the equivalant of the
longitudinal
component of the strings vibration. Which in itself is a diversion of
sorts from your
earlier description.  Or perhaps I missed something ?

> >
> >>
> >> And again, I'd like to get a better grip also on this "frequency dependent
> >> velocity of waves" thing in the panel. How does that fit with the
> >> description of the SB's movement as it had been presented up to early Dec
> >> last year ?
> >
>
> Ask Anders.

I was asking this list, and you too for that matter. I say again, we are
here to
simply exchange views, ideas, knowledge, and hopefully to grow.  But
ok... you
dont want to share your views. 

>
> Ron N

--
Richard Brekne
RPT, N.P.T.F.
Bergen, Norway
mailto:Richard.Brekne@grieg.uib.no