sentences:  A small gap should be left between the panel and the acoustic insulation so that the panel is free to resonate.Panel resonance can be enhanced by reducing the point of connection between the panel and the frame by means of narrow spacer material such as a loop of wire or welding rod run along the edge of the frame so that the panel is perched on a thin edge.Approximate full sheet [4' × 8'] plywood panel resonances when mounted on a 1×4 frame 3.5" deep are