Sound waves(The behavior of soundboards)

[Robin Hufford]

Richard,
     Being as I am, convinced of a view that is contrary to that of many, which is
a point I have acknowledged before, I say that this whole question, that of the
bridge/soundboard/string movement in pianos does not appear to have been given
adequate analysis, at least as far as I can find, in the literature available.
For example, in the Five Lectures, generally,  the idea that the string exerts a
force on the bridge which moves the board is taken simply as a point of departure,
a declaration is made as to this,  and the analysis proceeds on  to other matters,
for example modal behaviors.  Here, and elsewhere this particular question does
not appear to have been  scrutinized but, rather, taken as a given.   The opinions
of  those making these declarations, whether professors or not, do not represent,
at least to me, a thorough investigation of this question.  As regards pianos at
least this subject does not appear to have occupied much of the time of the few
researchers on the subject of pianos  who have usually been more interested in the
behavior of the strings, modal behaviors in the soundboard, action events, and the
like.
     The violin appears to have been the recipient of substantially more
investigative effort and, yet, one can find a  difference of opinion similar to
that of the two camps in this discussion, at least, tangentially, touched upon by
the commentary of some of those researching this field.
Regards, Robin Hufford

Richard Brekne wrote:

> Robin Hufford wrote:
>
> > Richard,
> >      Notwithstanding conventional opinion doesn't it plainly show that
> > longitudinal waves can, in fact, induce whatever wave motion exists in the
> > soundboard and do so in these instances?
>
> I think that's exactly what I said. :)
>
> > How this could insignificant is
> > incomprehensible to me.   The question then becomes "Can the transverse
> > loading (and by this I take it the Cyclic Pressurists meaning excursion of
> > the string during its standing phase)" induce similar effects such as are
> > proven to exists in definite longitudinal loading.  I am merely posing a
> > question here not offering an answer.
>
> Good question as far as I can see.  What I don't see is why such folks as
> Askenfelt, Russell, Weinreich, and others of their sort, who have all studied
> these matters at length seem to be saying that the answer in our specific
> discussion lies elsewhere.
>
> Course they could all be just figuring,,,, heck this fellow is an every day
> pianotech and doesn't understand much more then 12th grade physics... so we
> give him the simple version... or perhaps the difficult version is just a more
> detailed bunch of same.... what do I know.
>
> While you are on about Tuning Forks tho...(in your other post) I figured I
> would drop this due to the nature of the response I got last time (not from
> you), but someone (I wont say who) said something mixed in with a lot of
> unnecessary crass commentary about geometry being used to describe the
> elongation that happens in the shaft  when the tuning fork tines are in
> motion.  Incredibly complex you see.... high school geometry no doubt. Euclid
> in motion. :)
>
> >
> > Regards, Robin Hufford
> >
> > Richard Brekne wrote:
> >
> > >
> > >
> > > The point of this experiment is to show that Longitudinal waves can be
> > > introduced to the bridge and doing so will result in sound eminating from
> > > the soundboard. Or you can take it the other way and pump it across town
> > > into a zither if you want I suppose.
> > >
> > > None of this tho goes to show anything at all about the kind of waves
> > > generated in either soundboard or bridge.
> > >
> > > --
> > > Richard Brekne
> > > RPT, N.P.T.F.
> > > Bergen, Norway
> > > mailto:rbrekne@broadpark.no
> > > http://home.broadpark.no/~rbrekne/ricmain.html
>
> --
> Richard Brekne
> RPT, N.P.T.F.
> Bergen, Norway
> mailto:rbrekne@broadpark.no
> http://home.broadpark.no/~rbrekne/ricmain.html