pitch changes in long sustain

[Richard Moody]

Hi Jim, 
	Thanks for the reply. 
	 I have never noticed "pitch lowering" in piano
strings over a period of time.  Listening to A3-F5 I can't say I
hear the beat slowing.  Now that you mention it , it might be if I
listen for 8 or 10 seconds.  But I never listen to thirds or
tenths, for 4 seconds, 5 at the most.      
	I am wondering why this did not come up in the experiments of
Young and Schuck. ("Observations on the Vibrations of Piano
Strings" JASA Vol 15, No 1, July, 1943)  Perhaps their instruments
were not sensitive enough in 1943?  This is the kind of phenomenom
that should be right up the alley of the Acoustical Society of
America.  I wonder if any articles have been published on it?  
	I have to keep an open mind on this though, because I hope I am
not the first to admit that in tuning a 10th (to a Third)  in the
bass, once in a great while, I have gotten the tenth rate a little
better on the wrong pin.  ; )   Wrongoneric



----------
> From: Jim Coleman, Sr. <pianotoo@imap2.asu.edu>
> To: Richard Moody <remoody@midstatesd.net>
> Cc: pianotech@ptg.org
> Subject: Re: Unison coupling
> Date: Thursday, January 27, 2000 2:06 AM
> 
> Hi Richard:
> 
> The change in pitch of the middle and low end of the piano is
negligible 
> in repect to time especially when you are listening to beats.
However,
> in the 5th and 6th octaves, one can hear the difference in the
faster 
> beating intervals such as 10ths etc. Play F3 and A5 together.
Since the
> F3 does not change much in respect to time, the slowing of the
beat in
> this interval of a 17th is due to the fact that the A5 is
dropping in
> pitch. This is easily seen on  the SAT, but you can also hear it.
The
> change is more rapid at first than later.
> 
> Jim Coleman, Sr.
> 
> 
>