Sound waves(The behavior of soundboards)

[Carl Meyer]

----- Original Message -----
From: "John Delacour" <JD@Pianomaker.co.uk>
To: <pianotech@ptg.org>
Sent: Tuesday, December 18, 2001 11:19 AM
Subject: Re: Sound waves(The behavior of soundboards)


> At 8:00 AM -0600 12/18/01, Ron Nossaman wrote:
>
> >Not just yet John. One small nearly insignificant detail.
>
> Problem 2:
>
> a)  I take a small tack hammer and tap the bridge lightly but firmly
> on its top.  I then give a similar tap with the hammer on the side of
> the bridge.  The difference in the sound produced is very markedly
> different in the two cases.  It needs no trained ear to tell them
> apart.

How is it different?  Loudness, pitch or timbre?

>
> b)  I take a tuning fork or small tone generator and apply it first
> to the top of the bridge and then to the side of the bridge.  The
> sound emitted from the soundboard is the same in both cases.
>

Is it the same in loudness, pitch and timbre?

Now, one difference I see is that in one instance the bridge and soundboard
is the source of the sound due to its reaction from the impact  (the tack
hammer is not a hi Q resonant device and may produce many different
resultant tones) and in the other instance the tone source is the fork or
generator which will control the pitch.  I would expect the loudness to be
different since the acoustic impedance would be different top to side of the
bridge.  Interesting question, though.

I've never tried it, so I don't really know what's going on
I've never tried to drive a tuning pin with a tack hammer either.  That's
too tacky for me.

Carl Meyer  Assoc. PTG
Santa Clara, California
cmpiano@attbi.com

> Problem 3:
>
> Why can't I use the tack hammer to drive in tuning pins.  Why does it
> just bounce off the punch and fly up to the ceiling?
>
> Answer me those.
>
>
> JD
>