Ron, I have not maintained that the stem of the fork is not vibrating. Obviously it is and can be felt to do so and this is refered to in the post. Vibration being simply periodic motion both the tines, the base and the stem vibrate. They vibrate in different ways as the result of the difference in stiffness. A continuum of effect is demonstrated in the fork, at the risk of sounding repetitious I say once again that on the one hand we have transverse visible flexion; on the other molecular vibration, stress disturbance, etc. With regard to pressure - in the interests of accuracy perhaps you should have noted the sentence immediately following your quote: ..."Obviously, one could say that a pressure sufficient to destroy the system could easily be generated; evidently these effects would be different then and these kinds of pressure are not what I am refering to." Also, a little earlier....".The visible flexion can easily be stopped by the merest touch of a finger but no human hand can exert sufficient pressure to eliminate the stress wave in the base and stem that is felt as a vibration. " Clamping a fork in a big, heavy, vise, as you say, or hitting it with a sledgehammer and noting that its vibratory capabilities are altered should be no suprise to anyone. Similarly, putting a jack hammer above the bridge and driving it downward would most definitely introduce motion in the bridge whether the string was moving or not. I doubt that anyone would be surprised by this. The point of the comparison was to indicate the different results obtained by pressure at the two different points and that whereas a very slight pressure was sufficient eliminate the transverse vibration of the tines neither a similar or a much greater pressure exerted by the hand could have the same effect. This, among others things plainly illustrates that the two vibrations are of a different character which they are. regards Robin Hufford Ron Koval wrote: > Here goes, jumping in at the middle again! > > Robin Hufferd wrote: > Had this been the case then even a relatively light pressure upon the > bridge should immediately reduce the loudness of the sound emanating from > the soundboard as it does with the flexing part of the fork and a variable > pressure would introduce variable volumes in the sound. This is plainly not > the case. It is the case, however, that pressure upon the stem and base of > the fork does not eliminate the sound; and this is precisely what occurs > when pressure is applied to the bridge. > > Just to test the theory, I took out my trusty fork and gave it a listen. > Next, walked over to the big, heavy bench with the big, heavy vise. Clamped > it down good by the "non vibrating" end and struck it again. Hmmmmm...... > very quiet this time. Maybe no matter how tightly you clamp the fork in a > fleshy, nonrigid finger, you can't hear a difference. Yet clamped in a much > more rigid system, there is an obvious difference. In much the same way, a > strung piano soudboard/bridge assembly SEEMS to be rigid, yet allows > periodic motion (tone, as opposed to a hammer rap) to set the structure in > motion. Does it take a lot of energy? Nope, that's why pianos work. > > Ron Koval > > _________________________________________________________________ > Chat with friends online, try MSN Messenger: http://messenger.msn.com
This PTG archive page provided courtesy of Moy Piano Service, LLC