My starting caveat is that I'm no physics major, but I was contemplating the effect that temperature has on the pitch, as well. We often only think of the humidity level as being the only changing variable. However, when is humidity at it's highest? During the summer months when the temperature is quite a bit warmer, as well. And vice versa for the winter. I know that during the summer I tend to keep the temperature in the house a bit warmer so I'm not sending all my hard-earned cash to the electric utility. During the winter, my home is kept approximately 10-15° cooler so the gas company doesn't get all my income. I'm assuming many other piano owners do the same for their own homes. I know that cast iron and hardened steel expand and contract at differing rates, which could be the additional cause of pitch change. So, we have some change from humidity, some from temperature change, and some from the two different metals with differing coefficients of thermal expansion acting against each other. I just happened to have a big can of worms sitting in my cupboard that was about to expire, so I thought I'd open it now and share it with all... :-) Regards, Rob McCall McCall Piano Service, LLC www.mccallpiano.com Murrieta, CA 951-698-1875
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