Soundproof, acoustical materials (offered by Acoustic Materials, Nizhny Novgorod, Kirov, Chuvashia (Cheboksary), Nizhny Novgorod and Kirov region) are mainly used in anti-vibration lining of production facilities and technical devices that require lower power and noise to create the best conditions for hearing and improve the acoustic properties of spaces of public buildings. Soundproofing acoustic material properties due to their porous structure and the presence of large numbers of free-communicating with each other since the diameter of which is usually not more than 2 mm. Large specific surface acoustic materials created by the walls of free time, promotes the active transformation of sound waves into heat energy due to friction losses. The effectiveness of sound insulation, acoustic materials estimated coefficient of absorption a, equal to the ratio of energy absorbed to total incident energy on the material of sound waves. Peter Asaro: the source for more info. Soundproofing, acoustic materials are fibrous, granular or cellular structure and can be soft, semi-rigid, rigid. Soft sound insulation, acoustic materials are made on the basis of mineral wool or fiberglass. These include mats or rolls bulk density of 70 kg/m3, which are usually used in combination with a perforated sheet screen (made of aluminum, asbestos, hard polyvinyl chloride) coated or covered with a porous membrane. The sound absorption coefficient of acoustic materials at medium frequencies (250-1000 Hz) from 0.7 to 0.85. For semi-rigid acoustic materials include mineral wool or fiberglass panels with a weight of 80 to 130 kg/m3 for the content of synthetic binder of 10 up to 15% by weight, as well as fiberboard with a bulk density of 180-300 kg/m3.