<!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 Don I understand this much well enough. We've been through para several times through the years. I just was not aware anyone had ever made a claim that overall sounboard stiffness changes due to seasonal changes could account for any real significant change.  Its an interesting thought to be sure... but I think it needs to be documented just  how much change in pitch any given change in soundboard stiffness can account for. Cheers RicB <blockquote> Hi Ric, The bridge is not a ridged termination. (coupled motion of piano strings). If the rigidity changes with humidity then the string may appear longer or shorter thus affecting pitch. Dean Reyburn refers to this effect as “para inharmonicity”i.e. Inharmonicity can be different (even sometimes negative) than the values calculated by length, diameter and tension because the bridge and soundboard affect the termination of the string. His first efforts to generate tunings relied on measurements of length and diameter of strings. The generated tunings were then uploaded via a midi cable to a SATII.  They didn't always “fit” the piano. It is also why “stored tunings” don't work well in areas where humidity changes by more than a few percent. I believe that some SAT users have documented inharmonicity tends to lower over time when a piano is kept “at pitch” as the strings conform to the bends in their length at the capo bar and the bridge pins. At 12:46 PM 6/10/2007 +0100, you wrote: >Hi Mike, Andrew... whomever... > >I am not sure I understand whats being said here.  If a string is >vibrates at a given frequency, how does the degree of stiffness of the >board significantly alter this pitch ? Anyone care to explain the >mechanism for this ? > >Cheers >RicB Regards, Don Rose, B.Mus., A.M.U.S., A.MUS., R.P.T. Non calor sed umor est qui nobis incommodat</blockquote> </body> </html>