Noise reducing materials lessen the energy of sound waves as they pass through whereas noise absorption equipment suppresses the echoes, reverberations, resonance and reflections of sound waves. It is important to understand the specifics of the desired results and which types of sounds are to be reduced as soundproofing materials can be applied in a variety of manners. Acoustic flooring, panels, ceilings and anechoic chambers may be used alone or in conjunction with each other and other components depending on the needs of a space. The specific fabric or object used depends largely on its intended function. Industrial, commercial and residential settings all make use of soundproofing materials to make spaces more acoustically pleasant. Recording studios, edit rooms, research facilities, function halls, gymnasiums and even laundry rooms commonly utilize these materials to lessen the impact of sound waves. Industrial machines are often secluded by acoustic curtains made of materials that block noise to protect the ears of nearby workers.
In general, soundproofing involves allowing sound waves to penetrate high mass and porous materials that essentially trap the noise and prevent reverberations which would send noise pollution back into a space. The most effective materials also increase the ratio of sound barrier surface area to open space. More surfaces to absorb noise allow sound waves to dissipate more fully. For this reason, the majority of soundproofing materials are corrugated, uneven, or jagged in appearance to increase the potential surface area for sound wave absorption. Materials with good non-conductive properties and relative permittivity near unity function best for soundproofing. Rock wool, sheetrock, foam wedges, high mass vinyl, fiberglass, rubber, aluminum composite, glass, polyethylene, mineral wool, heavy caulking, urethane open-cell foam as well as soundboards made of compressed wood and paper are all used as sound proofing materials. Some of these materials, such as foam wedges, can be injected with carbon or ferrite to increase the absorption of sound waves. Mineral wool fibers are good example of soundproofing options that are non-combustible and have high melting points allowing them to be used around heat generating industrial machines without serious risks. These materials can be applied during or after construction of a space, however post-construction soundproofing is often far less effective than installing a sound-proofing material from the beginning.