When it comes to controlling unwanted sound in a studio, there are two basic solutions: absorption and diffusion. Absorbing materials attempt to eliminate sound reflections and standing waves. Diffusors reduce the intensity of sound by scattering it over an expanded area. Absorbers are more commonly used in radio facilities since the goal is to eliminate the reflections.

In radio, the foam design is most commonly used, but cloth-covered panels run a close second. Both are available in a variety of thicknesses, which affects the frequency range of the absorption. Foam panels are usually glued to a wall surface, while cloth-covered panels can be glued or hung like a picture.

Typical materials are open cell polyurethane foam, cellular melamine, fiberglass, fluffy fabrics and other porous materials. In the last few years, fire-retardant and fire-proof materials have gained in popularity.