longitudinal waves, MiniMens

[gordon stelter]

Excuse me, please, but is not the piano tone actually
caused by the tugging of the string on the bridge cap,
effectively making it a "bell crank"? Afer all, as a
string vibrates, the end pulls in and out, not up and
down. If it waved up and down, lifting and dropping
the bridge with it, the tone we hear would be the
frequency of the entire string--- from agraffe to
hitch pin. But it isn't.
     Thump
--- Bernhard Stopper <b98tu@t-online.de> wrote:
> Dear Marc & Isaac,
> 
> Longitudinal waves of strings produce transversal
> vibrations on the
> soundboard caused by the bridge´s back and forth
> movement. If this would not
> be the case, one couldn´t measure or hear them. I
> think you don´t negociate
> that they exist, in the sound samples it is the
> whistle you can hear. As
> Isaac wrote, (he supposed it was the additional line
> below the 4.
> transversal but heard it an octave higher. It is
> overlaid with the 13.
> transveral, so that is indeed what you heard, (good
> ears Isaac, i am really
> impressed... )
> 
> Measuring and separation of transverse and
> longitudinal harmonics were done
> with a software spectrum analyzer (spectraplus, you
> can download a test
> version at http://www.telebyte.com/pioneer/ ). A
> spectrum analyzer extracts
> every frequency that is in a sound wave over time,
> no matter if it is caused
> by a longitudinal or a transversal wave.
> 
> To interpert the spectra, just "count" the regular
> lines.. there are 39
> transversal waves, and the first longitudinal wave
> (at about 712 Hz) is
> overlaid with the 13. transversal (a little thicker
> line) The various
> additional lines (mainly around the mid of the
> spectrum) are caused by the
> blank ends,  the wave propagation is faster on that
> part of the string what
> results in splitting up several harmonics.
> 
> to ask for a MiniMens Audio demo (the string
> simulator) and more information
> on the MiniMens program look here:
> 
> http://www.piano-stopper.de/homepe.htm
> 
> best regards,
> 
> Bernhard Stopper
> 
> ----- Original Message ----- 
> From: "Mark Kinsler" <kinsler33@hotmail.com>
> To: <pianotech@ptg.org>
> Sent: Wednesday, February 11, 2004 6:09 AM
> Subject: longitudinal waves
> 
> 
> > So there's a program that'll simulate the behavior
> of a stretched string,
> > non-linearities and all?  I suppose I shouldn't be
> surprised, but I'm
> > certainly impressed.  And the recording and
> simulation sounded alike
> (though
> > the attack, etc. was different.)
> >
> > I'm sitting here wondering how you could measure
> longitudinal waves on a
> > string separately from the transverse waves.  It's
> easy enough to detect
> > motion in a plane perpendicular to the string, but
> how would you isolate
> > longitudinal waves?
> >
> > I wish those two spectra had some labels on them. 
> I couldn't figure them
> > out.
> >
> >
> > M Kinsler
> > 512 E Mulberry St. Lancaster, Ohio USA 43130
> 740-687-6368
> > http://home.earthlink.net/~mkinsler1
> >
> >
>
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