Sound waves(The behavior of soundboards)

[Ron Nossaman]

>Ron,
>     A longitudinal wave experiences reflection from a free end just a does a
>transverse wave.  In a transverse wave reflection from a clamped end
results in
>a phase reversal, that from a free end does not.  Longitudinal waves are the
>reverse.  Reflection from a free end results in a phase reversal, now
expressed
>in terms of a rarefaction and compression.  The compressive phase reaches the
>end of the medium where it is not longer opposed by the physical
>characteristics of the medium as had been the case prior to reaching the
>boundary.  The force of the compressive oscillation causes the medium
itself to
>bend outward at the boundary resulting in a phase reversal in which a
>rarefaction then proceeds back through the medium.  

Robin,
I understand well enough how transverse and compression waves work. What
point does this paragraph address?


>There is no need to posit
>any kind of physical, substantial motion to account for the bouncing of the
>fork.  In fact, such an idea is thoroughly erroneous.   The reflection
from the
>end of the fork causes the stress wave which is, in fact, what we are talking
>about here, to demonstrate itself as a kind o displacement of the end.
This is
>strain and does not require the fork to be moving to occur.  Such an idea
is at
>odds with every analysis of this subject.

And which analyses are these? Where might I find every one of these
analyses of the details of handle movement in a tuning fork ruling out mass
reaction? I'm not interested in one "expert's" opinion, or what a
superficial animation on a web page seems to imply. Once again, you make
the reference, but don't produce the sources. I'd very much like to see the
science and reality based analysis that makes your case. Geometry and
Mathematics tells me that when a bar is bent into a curve, the end points
come closer together in space than when the bar was straight. That comes
under the heading of established observable and demonstrable physical
reality and seems to me to be pretty much inescapable except through denial
of physical reality. Newton tells us that for every action there is an
equal and opposite reaction. This supposition has held up in practice with
similar dependability for the last three hundred years or so. With the
length of the fork changing constantly through each cycle, the center of
mass will have to change with the relative weight distribution and motion,
and the handle will have to move accordingly. That is basic physics, and
there is every need to posit these effects purely because they undeniably
exist. Any entertainable supposition denying established physics principals
and effects must either rule out these effects or prove the entire body of
established physics to be invalid. That will take a better model than you
are presenting. I fail to see how the idea is erroneous strictly because
you say so, and particularly in the continued absence of documented physics
base supporting your claims. 


>     Now I find you using the very same models to demonstrate longitudinal
>behavior which last month you claimed could not occur, practically did not
>exist, and if extant, was of no consequence, including taking into account the
>effect of stress on longitudinal wave behavior in a tuning fork.
>Regards, Robin Hufford .

You lost me there. What longitudinal wave behavior? What did I say then to
contradict what I'm saying now? I've always said that fork tine motion
physically moved the handle up and down. Transduced stress compression
waves have, as far as I can tell, little if anything at all to do with
soundboards, bridges, or tuning forks. While they may exist, I've seen no
evidence that they exert any but very minor influences on the systems. I've
never said anything different that I am aware of. Enlighten me. What are
you referring to?

Ron N