If you did a raised floor, you could stuff the "empty chambers" with loose insulation - depending on the size of the panels and stiffness of the material, they would effectively be a resonating chamber. there is some math that would help you figure out what frequency those chambers would resonate and absorb at.
I did something similar with my 10' projection screen. It's made with a stiff frame that has white counter top material stapled to it - makes for a wonderful projection screen, but resonated at a couple specific frequencies. I simply tacked some "acoustic blanket" to the back side and saw quite an improvement to the bass in the room. The screen acts like a membrane, and the acoustic blankets soak up that noise.