Perhaps "yowing" also encouraged by excessive/improperly twisted strings? Loose bridge poins? Just a thought. Thump --- Bill Ballard <yardbird@vermontel.net> wrote: > At 4:34 PM -0500 1/23/03, Sarah Fox wrote: > >Very cool. Now I know the name. <smile> Just to > expand on this > >concept, if the impulse (i.e. hammer blow) > delivered to the string > >has both vertical and horizontal components, and if > the vertical and > >horizontal components are not simple scalar > translations of each > >other (i.e. that the horizontal force is a fixed > multiple of the > >vertical force, such that they could be resolved as > a simple, > >unidirectional impulse at an angular direction -- > highly doubtful), > >then the initial horizontal and vertical spectra > would have > >different relative representations in the different > harmonics > >(partials). As a result, the resultant angle of > vibration would > >differ between harmonics. (Think about it.) Now, > considering the > >inharmonicity of the string, the phasing of the > different harmonics > >would drift. As they drift, angle of vibration at > any given > >position of the string would also drift, i.e. being > the sum of the > >vibrational components from each harmonic, which > arguably are set at > >different angles in an imperfect system. Add to > the cocktail that > >nonlinearities in string behavior would result in > the gradual > >transfer of energy from lower frequencies to their > harmonics in > >the *same* vibrational direction as the lower > frequencies, with > >those frequencies summating with the (slightly > different frequency) > >harmonics at different vibrational angles, thus > causing a shift in > >the angle of the resultant vibrational component. > YOW!! > >WOW!! This could make a person's brain bleed! > > You really enjoy "writing out loud", don't you. (Me > too, along with > bypassing the shellch-ecker <g>). > > The story which I heard is from Barney Ricca, former > PTG member, > actually a physicist at one of the Texas > universities. At the '95 > Albuqueque National, he was summarizing the > conventional wisdom, > saying that in the initial impact, this wave form in > the string , > viewed axially, would be purely vertical. This would > last for a short > interval (proportional to the total sustain time) > until the string's > energy would spill into the other (infinite) modes, > to remain stable > in that chaotic "omni-mode". > > The initial single mode is actually the prompt > sound, that time > period when the string is feeding rapidly into the > bridge. Entropy > compels the vibrations into a choatic mode which > fortunately for us, > also extends its sustain. This latter phase is > called the aftersound. > > But what do I know, I've barely got a high school > diploma. > > Bill Ballard RPT > NH Chapter, P.T.G. > > "Woh" > ...........Keanu Reeves in "The Matrix" > +++++++++++++++++++++ > _______________________________________________ > pianotech list info: https://www.moypiano.com/resources/#archives __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com
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