Types of acoustic Material

Polyurethane is quite useful at attenuating high-frequency sound waves, but it does not store low-frequency isolation unless sufficient thickness is used. The porous quality of polyurethane greatly reduces acoustic reflection, but this low density also provides for the transmission of sound energy. Acoustic foams are chemically inert, so Polyurethane foams may not be used in industries. It is more suitable for installation within a room.

Felt is created by pressing and matting fibres together. Fibres use may be natural (mostly wool) or artificial. A combination of both is also common. Felt is strong and stable in the presence of moisture, lubricating oils, greases, salts, detergents, and is inert to many other chemicals. Its capability to bend to uneven surfaces prevents the unwanted invasion of foreign substances beneath the load-bearing area. Felt possesses almost permanent resilience, as it is made up of millions of individual fibres. The performance of felt in sound absorption is a result of its optimum density and spring. 

Polyester fibre is a man-made fibre, made up of long-chain synthetic polymers. They are generally known as non-woven or bonded fibre fabric. They are used to make non-toxic, lightweight insulation products. Polyester fibre is spectacular for its unique blend of heavy density (approximately 2000g/m^3) and porosity. Its sound absorption increases with the frequency of the sound, hence it's most effective at high frequencies. Its NRC rating is between 0.8 and 1.Polyester fibre is also strong with high tensile strength. Other desirable properties are its resistance to abrasion, fire, wrinkles, stretch, impact and wear.

Fibre Glass. Acoustic fibreglass has a desirable combination of rigidity and being lightweight. Popularly dubbed, the shapeshifter of soundproofing, this material can be very easily customized, to allow for installation in the tightest of places. Glass fibre is mostly used in rooms and halls to prevent reverberations and echos.

• Cork is an amazing natural alternative for soundproofing.
• Green glue is a viscoelastic compound that insulates sound using the constrained layer damping system. 
• Silicone is a good soundproofing option for tight spaces and corners.
• Epoxies' usefulness in soundproofing is a result of its air resistance and damping properties.