Given the density of a surface against which sound will reflect, this calculator will estimate the percentage of the sound wave that will be reflected back. Keep in mind, this does not account for all the real-life factors affecting sound wave reflection, and is meant to show you a "simplified" approach to calculating reflection intensity.
Drywall: 668 kg/m3
Brick: 2000 kg/m3
Glass: 2500 kg/m3
Absorption Products: 30-100 kg/m3