I might be wrong since I haven't considered this before, but I suspect the behaviour is intended, and there appears to be a physical reason for the decays to be different.
Someone else may of course come along and answer straight off..
My thinking would be that a hammer struck note exhibits double decay, whereas it seems to me that sympathetic resonance would not.
Considering from Pg 26 - 29 here:
https://www.jjburred.com/research/pdf/b..._piano.pdf
the long decay time of an undamped note is achieved by the resonance behaviour of the struck string, and its energy exchange between strings and soundboard through the bridge. It relies on the development of out-of-phase string vibrations after the initial hammer strike, to give partial cancellations and couple less energy into the bridge, delivering slower attenuation of the tail of the note. The characteristic of a hammer strike is considered an important contributor to the string behaviour, delivering high but mechanically imperfect initial energy input directly to the strings, which is then coupled to the soundboard at a higher loss during the short initial in-phase string mode, but quickly changes to out-of-phase modes giving the double decay rate.
Sympathetic resonance works in the reverse manner, initial energy is coupled to the strings through the soundboard and bridge, and this will pass a small amount of energy into the strings in phase, which means the strings will vibrate in the high loss immediate sound mode, and attenuate more quickly.
If you listen to the tail of a struck and undamped note, you can hear the development of the out-of-phase resonance mode in the tail of the note. If you then keep the, say B5, note open and strike B3 as you've indicated, you'll hear the sympathetic B5, with a shorter tail, but no phasing, it is a unison note. It seems to me that this should attenuate faster.
The effect can be heard in all the PianoteQ models I have, but currently I don't have access to an acoustic piano to assess how accurately it resembles physical piano behaviour. Because of the vagaries of human hearing, that might be trickier to determine than listening to headphones!
Last edited by Platypus (06-01-2021 14:37)
