We have this big, modern, geometric painting over the fireplace - right where I would like to have put a panel to absorb reflections from the left front channel:
Fortunately, paintings on stretched canvas have a recess in the back that is just the right depth for 1" Owens-Corning 703:
You may want to do this modification well out of arms reach of the spousal unit, just in case something goes horribly wrong. There were some tense moments while I nailed in a few brads to hold the fiberglass in place. Fortunately everything came out just fine:
Clearly this "acoustic panel" does not absorb in the high frequency range (the canvas and paint reflect most of this) nor the bottom end of the low frequency range (it's too thin). At the moment I am speculating that the midrange and/or mid-bass frequencies (maybe 250-2500Hz?) are at least somewhat absorbed by this device. I need to come up with a way to measure this (without having to take it back apart - this project was too stressful for a redo) because for all I know it may be useless acoustically. At worst, there's an extra 1" of insulation on that part of the wall now!