<!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 Ric The coupled motion of strings is a description of the physics behind how more then one string effect both the termination and each other when put into vibration. The so called pitch drop Virgil Smith, Dr Coleman and a host of others claim is a related subject matter but it is not in itself the same thing. More like a predictable result when two strings combine to force a bridge into vibration. It is in my opinion entirely possible that in some instances the pitch will not drop, but raise... or not seem to be affected.  The reason for this is also to be found in the 5 lectures.  The bridge impedance at each bridge pin also must be considered. Another interesting and highly respected modern piano researcher, Dr. Nicholas Giordano from Purdue is worth reading on this and related subject.  He has for example recently shown conclusively that the longitudinal vibration mode of the string is quite a significant... for not to say decisive part of the attack portion of the sound the soundboard releases, and that this effects the overall sound.  He also has some interesting things to say about longitudinal vibration in the soundboard itself. There are many piano techs claiming to have far greater insights into these subject matters then they can possibly have.  The fact is there are a handful of bonified researchers out there with the physics knowledge to describe adequatly these things, and all of these that I have read or talked to are quite ready to remain quite humble when claiming anything like <<conclusive truths>>  If it can be measured, fotographed, or otherwise observed... then ok... but complete descriptions as to why most of these things happen are still mostly very advanced ponderings.   Very well founded perhaps... knocking on the door of understanding perhaps... but ponderings none the less.  Cheers RicB <blockquote> Is this pitch drop that Virgil Smith mentions, is it the same as "coupled motion"?  Did he call it that?  Who then came up with the name?      I can demonstrate the opposite.  I can tune a unison that will show the pitch rising from the first string tuned.  And this would be a unison that agrees with any RPT.   Lets do it at a convention.  I will pay for the booth if each visitor chips in a dollar.  (As an added truth, I can also demonstrate it can go down in an acceptable unison.)  That ought to make it worth $2.00 a visit.    Richard Moody     </blockquote> </body> </html>