Leveling of strings

[Susan Kline]

Hello, list --

Michael's theory about hammer torque and motion led me to consider what
would happen if only the middle string were high. Presumably, there would be
no torque, and therefore no strange sound? Has anyone noticed a difference
in the obnoxiousness of the sound correlating to which strings were high? If
what I'm considering makes sense, the most motion and torque would probably
occur when one of the outer strings was lower than the other two, and the
greater the difference in height the worse the tone. 

Also, wouldn't poor hammer traveling produce the same effect, since one side
of the hammer would strike slightly before the other?

Just thoughts ... certainly no evidence!

Yours,

Susan

....................................

At 09:42 AM 8/1/97 -0100, Michael Wathen wrote:
>I've been thinking about this problem.  What I think now is that it has
>nothing to do with the relative phases of the three strings.  More likely,
>the strange sound that occurs when the hammer strikes strings that are not
>level, is in fact due to the motion of the hammer. 
>
>Suppose the left string of a unison is slightly higher.  This means that the
>hammer will strike the middle and right string first causing a Torque force
>to be applied to the hammer head. The hammer would then twist and possibly
>slide slightly up to make its contact to the left string of the unison.  The
>resulting motion of the hammer head from then until it actually leaves all
>of three strings behind would be a kind of quiver effect.


>
>There was the argument on Pianotech a couple of years ago about how the
>hammer string contact time effected the dampening of higher partials.  I
>remember that the consensus seemed to be the belief that the longer the
>hammer remained in contact with the string the more the higher partials were
>dampened. I presented what I thought was a more likely scenario that applies
>to the leveling question as well. My belief is that the contact time changes
>the shape of the traveling wave on the string.  The shape of the wave on the
>string is not completely determined until the moment the hammer leaves the
>string. Why is the different from the consensus model above?  The consensus
>model has the hammer resting against the string and high frequency waves
>returning from the termination points of the string being absorbed and
>essentially killed by the hammer still in contact with the string. The
>assumption is that these little high frequency wavelets return from the
>termination points first.  My idea is that these little wavelets do not
>separate themselves from the main impulse and travel at a faster speed down
>the string. In fact, that's not possible in the standard string equation
>model except for the longitudinal modes of the string. 
>
>In the case of non-level strings,the wave shape due to the contact of the
>hammer's twisting while contacting would certainly give a more out of the
>ordinary shape to the wave on the string. 
>++++++++++++++++++++++++++++++++++
>Michael J. Wathen, Rpt
>Cincinnati, Ohio USA
>michael.wathen@uc.edu
>
>http://ucccm56.ccm.uc.edu
>
>..................................................................
Susan Kline 
P.O. Box 1651
Philomath, OR 97370
skline@proaxis.com

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