impedance and empericism

BobDavis88@AOL.COM BobDavis88@AOL.COM
Thu, 15 Jun 2000 16:02:08 EDT


Marc Damashek writes:
> If the frequencies implausibly change by different (relative,
>  fractional, percentage, NOT absolute) amounts when the piano structure 
> swells and raises the tension, then all bets are off.

What some people are saying is that the relative frequencies DO change.

If they are right, (and my casual observations support this; I haven't had 
time for a controlled experiment), here's how it would be possible:
1. Inharmonicity is dependent upon, among other things, the length of the 
string for a particular pitch. 
2. As the moisture level of the soundboard changes, its stiffness changes. 
3. Because of a stiffer termination, the string "acts" shorter, even when 
returned to the original pitch, changing its inharmonicity.

Also:
If the soundboard swells, what makes the pitch go up? Doesn't the deflection 
from horizontal increase, and doesn't the string get longer? If the tension 
is then lowered on that string, doesn't the string remain longer because the 
sbd is in a different position? 

Bob D


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