Sound waves(The behavior of soundboards)

[Richard Brekne]

Ron Nossaman wrote:

> >
> > Hmmmm. Seems to me that the visible wave represents one aspect of wave motion
> > and the actual sound we could hear if we stuck our heads underwater would
> > represent another aspect of the whole induced motion thing.
> > Joseph Alkana  RPT
>
> Joseph,
> Certainly, but what induces the motion in the first place? Will a compression
> wave introduced directly into the water at a molecular level without displacing
> water make ripples like a tossed in rock?

I really dont understand this question Ron. And its seems by it, as I have said
before evidence again of some pretty severe "talking past each other"  What do you
mean by "introducing a compression wave directly into the water at a molecular
level" ? And where did you get the idea anyone was talking about that ?

> The wave produced will be a
> compression wave, and travel at the speed of sound in water, not a transverse
> surface wave traveling much more slowly  because it won't displace water like a
> rock in a pond, or the soundboard surface like a string moved bridge in a
> piano.

Any compression wave created in the water will "displace" water. These "transverse"
waves on the surface are nothing more then the  compression waves interacting with
the surface of the water and the air. What do you expect of a compression wave
moving outwards in all directions .... also along the surface.  Do you really
expect the surface to remain still ?? Please explain.

>
> Some mass in an elastic membrane has to be displaced perpendicular to the plane
> of the membrane to get a transverse wave. I know how the moving mass of the
> rock or string does it, but how would a molecular level compression wave do
> that? That's the question.

As I have said... it seems to me that the wave IS the motion. Transverse waves can
only exist when two differing medium are involved. Can you picture a "wire of
water" in a "lake of water" vibrating transversely ? Of course not. You have three
basic medium types. Liquids, solids, and gas. The mechanics of vibration are
described by wave mechanics, and that, difficult as it may be to accept, gets into
all this about molecular displacement.

The more I read these "differing views" the more it becomes apparent that there is
a lot of misconceptions going on about what each other is saying.

>
>
> Ron N




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