<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><DIV><DIV>On Jun 7, 2007, at 2:21 PM, Fred Sturm wrote:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"><SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; ">One of the Fandrich's (I forget which, but think Darrell) wrote about pitch change due to elongation of the bridge toward the tenor end about ten years ago, citing speaking length change as a major factor.</SPAN></BLOCKQUOTE></DIV><BR><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>I looked up that article, (7/96, by Darrell), and confess I am more confused reading it today than I was then. Very interesting article, filled with calculations and observations. I _think_ the point he was making was about treble bridge expansion "along the grain" causing greater pitch change at the bottom of that bridge, based on the bridge pins "pulling" (elongating) the wire (ie, friction between pins and string allowing the bridge to pull the string away from the front termination, thereby raising tension). He writes of creating greater physical stability in that area of the soundboard assembly (adding wood and screws), and that this had a noticeable and dramatic impact on stability of the bottom of the treble bridge. But I guess I don't really follow all his explanations. DIdn't at the time, to the point of writing a long and rather pompous letter to the editor finding fault with his calculations. [It can be rather embarrassing to look back at oneself from a perspective of ten years later <G>.] </DIV><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>Anyhow, there are a few articles by Del, mixed with a couple by Darrell, and a few letters by yours truly in that period of a few months before and after, speculating about wood and moisture and pitch. Perhaps we are a little farther along in our knowledge of these things now. Sometimes I wonder <G>. I promised to do a whole lot of research in a couple of those letters. Never found the time to do it right (documenting). Just kept observing and puzzling. I feel a lot more puzzled now than I did then. I think I know a good bit more about how things behave (as in what pitch change is observed following humidity change, what patterns occur, and what variants), but the mechanism and the theory behind it are more clouded than ever - much more complicated. </DIV><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>I will say that Ron's observations about bridges and bridge pins are definitely an enormously valuable contribution to the mix. I'm curious about what data is out there physically and accurately measuring soundboard rise and fall on strung pianos in response to humidity change. Have there been such measurements? One reads a lot of assertions about seasonal increase/decrease in bearing and crown and its affect on tone quality. Is that just fertile imagination, or are there physical measurements to back it up?<BR><DIV><DIV>Regards,</DIV><DIV>Fred Sturm</DIV><DIV>University of New Mexico</DIV><DIV><A href="mailto:fssturm@unm.edu">fssturm@unm.edu</A></DIV><DIV><BR class="khtml-block-placeholder"></DIV></DIV><BR></DIV><DIV><BR class="khtml-block-placeholder"></DIV></BODY></HTML>