<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type"> <title></title> </head> <body bgcolor="#ffffff" text="#000000"> Hi again <blockquote> There are two separate issues both influencing string length, ultimately: 1) a change in the moisture content of the wood in the piano which influences the speaking length due to expansion and contraction 2) a change in temperature which changes the length of the string directly.  </blockquote> Ok enough. <blockquote> The issue is how a change in speaking length affects a change in pitch and which factors contribute to the degree to which there is a change. </blockquote> I've been saying this for quite a while now, and posted a very easy to follow algorithm for how do calculate just this. <blockquote> It's not that difficult, if you want to take the time, to algebraically alter the formula for string tension, diameter, length and pitch to isolate pitch as the dependent variable.  Set up two notes of equal pitch but different tensions/BPP etc.  Notice what must be different in order to achieve equal pitch.  Find out what happens to pitch with an equal change in speaking length of each.  </blockquote> You can not solve for change in pitch directly by re-writting / re-arranging the formula for string tension. You can not because any given change in length automatically carries with it a change in tension i.e. you have two unknowns.... tension and length.  Length change is easy to calculate with the simple trig talked about. But that leaves you with an unknown change in  tension still. You could measure pitch of course and calculate the new tension that the new length resulted in...... but aside from being the long way around... we are solving for pitch.  Its easy enough to do... just calculate the change in length, and then the resultant change in tension.  Then you have all the variables you need to calculate for resultant pitch. Thats.... for a string whose vibration period is truly reflected by the soundboard... and not altered significantly due to any stiffness issues... which just came up and of course sheds a different perspective on everything to the degree that thought ends up being significant itself. Cheers RicB <blockquote> David Love davidlovepianos at comcast.net <a class="moz-txt-link-abbreviated" href="http://www.davidlovepianos.com">www.davidlovepianos.com</a></blockquote> </body> </html>