Hi Keith
Per @user44455555' process, I generated the detailed plot on RT60 decay window, before switching back to the overlays. This way the RT60 overlay has much higher resolution, even in overlay mode, i.e. at least in the T60M trace. In the jpeg snapshot I attached to above post it you can see the spike @160, whatever that is. Probably a mode? I'll try to do a screen grab tonight, since the export didn't capture the cursor or settings I used.
Re: you paintings: If the wall is vibrating, the pressure wave (sound) of that oscillation will go back into the listening room, right? I assume at whatever the natural / harmonic frequency the wall is. Might not be audible, but it should be there.
My question: Is the vibration of the frames rattling against the wall at that same frequency, or is it at a new, unique one? If the same, it just vibrate in perfect phase with the wall, and create a uniform pressure wave. The felt pads would have no effect, no? However If they vibrate at a new, different harmonic frequency (it is a new structure, after all) the felt pads merely dampens the sound of the two colliding structures (interfering waves), but the wall / frames / canvas is still creating a pressure wave, right? I wish I paid more attention in college!
I wonder if it makes sense to for me to try and generate a fixed 160Hz sine wave, and to see if I can hear/ feel anything suspicious or misbehaving in the room. The same might help you find the rattle. But it might also be a fools errand.
Cheers!
