3rd find: Symp resonance exists, and the MP3 below demonstrates it. In the file (rendered from a midi test file so that I could ensure absolute control over note duration and velocity) I play four times a staccato C3 (vel=127). The first C3 is played alone: no symp resonance. Then I play an octave (G1 through G2) at vel=1 and hold the notes; notice how loud a chord at vel=1 is !!! After the octave notes completely decayed but while the keys are still maintained, I play the second C3 and a strong symp resonance can be heard. Then I release all hold notes except C2 (still at vel=1 and completely silent at this moment) and I play the third C3: now a C2 resonance can be heard. Then I release C2 and play again C3 and no resonance occurs (although the render ends abruptly, the effect is exactly the same as in the first C3).
vagfilm, thank you for taking the time to provide such interesting data.
No, I don't think the point is proven, I don't think a usable, realistic, musical resonance exists.
On your second hit of C3 a strong resonance of C3 itself exists. That's a very silly effect and not the real sympathetic resonance that you normally hear in an acoustic. Symp resonance is when ANOTHER
string is excited by the one being hit. Not the case here. This effect gives kind of an halo to the C3 itself, very unrealistic IMO.
As for your third hit, yes a C2 resonance can be heard, proper resonance, so feeble you really need to listen closely. A real acoustic instrument has a much much louder resonance and so does a well implemented software (Garritan)
So my opinion is that symp res here if it does exist is so poorly implemented as to make it unusable.
In any case thank you so much again for such a valuable, real data contribution.
(sidenote, I would never have expected such a debate on such a technicality . . .interesting . . .)