[impedance]

[Richard Moody]

----- Original Message -----
From: Robert Scott <rscott@wwnet.net>
To: <pianotech@ptg.org>
Sent: Wednesday, June 14, 2000 12:11 PM
Subject: Re: [impedance]


> Don Rose wrote:
>
> >With todays technology it is *already* possible to prove that the
frequence
> >of the partials change with voicing and also with the changes in the
> >humidity content of the sound board.
>
>
> I don't think it has been proven.  A lot of well-respected people
> have certainly made their opinions known, but that does not constitute
> proof.  .............
. > We know that the pitch of a
> string is higher when it is played louder because of the increased average
> tension.
> -Robert Scott
>  Real-Time Specialties

The pitch is higher because a louder string is under more tension?  This
leads to the conclusion that since a string is always decreasing in volume
it therefore should be decreasing in tension and therefore decreasing in
pitch.
By such logic one might say that a louder string has more amplitude, which
makes that string longer.  But a longer string means a lower pitch.  So why
not consider that? Perhaps that is really what happens (the string gets
longer, and more tension) but  they cancel each other out, so that is why
the string always vibrates at the same pitch.  I have always thought it was
part of the nature of elasticity that a string is at the same pitch no
matter how loud (or soft) it is sounding. I have never found evidence for a
string changing pitch because of volume, even using Tunelab.   OK I have
heard it might can be detected in the first
milliseconds.  But what about the ensuing . 5 seconds, 2 seconds, 5 seconds,
or 10 seconds?
    An interesting experiment might be to pluck the string.   Measure the
height the string is raised, calculate the increased tension by vectors,
release the string from that height and measure its freq, and see how long
this initial frequency lasts.  Tunelab would work real good for this I
think.  Sooner or later the string should vibrate  at  predicted pitch for
its length, tension and diameter. ---ric