Sound waves(The behavior of soundboards)

[Richard Brekne]

Delwin D Fandrich wrote:

> > >
> > >When these compression waves supposedly travel down through the bridge to
> > >the soundboard, moving the board before the bridge moves, how does this
> > >manage to happen with the board attached to the bridge at exactly the
> spot
> > >that these waves are supposed to move the board? I'd love to know the
> > >mechanics behind this.
> >
> > For the same reason that the wine glass does not shatter the moment
> > the lady sings the top C but a moment afterwards.  The glass is
> > unaffected while the wave is travelling towards it.  Surely this is
> > obvious.
> >
> > JD
>

Hmmm JD... not sure of the relevance to this thread.. When a singer sings a note
at precisely the natural ringing frequency of the glass, the glass vibrates in
response to the note. If the voice is powerful enough, the vibrations can build
up to a high enough amplitude that the glass actually shatters. In order for
this to work, the singer must sing the note at precisely the frequency at which
the glass rings when you thump it. This is the "natural resonance frequency" of
the glass. If the singer is even s lightly off-pitch, then the glass will not
vibrate. We are talking about reasonance frequencies here...and degrees of
amplitude buildup in the glass itself not some delay related to any time span it
takes a wave to pass through the air and hit that glass.



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