Materials that help make walls soundproof include drywall, mass-loaded vinyl, fiberglass insulation and noise-control curtains. Supplementary materials include damping compound, acoustical sealant and decoupling hardware.
Drywall panels such as Sheetrock are inexpensive and provide mass to reduce sound. Damped drywall contains a layer of a sound-damping compound. Two brands of damped drywall are SilentFX and QuietRock.
Mass-loaded vinyl is good for wrapping ducts, pipes and columns because it is a flexible material. It is also useful for filling gaps, but it expensive for use as a layer in walls. Sound curtains contain a layer of mass-loaded vinyl. Fiberglass insulation provides sound absorption, which helps dampen sound, but does not soundproof by itself.
Using a damping compound such as Green Glue Noiseproofing Compound or QuietGluePro between two layers of drywall or plywood can block low-frequency stereo and construction noise. Acoustical caulk seals seams to stop sound from leaking through the cracks. Preventing sound leakage substantially increases the effectiveness of soundproofing panels.