Airborne sound absorption

Airborne sound absorption, often simply called sound absorption, is necessary when the noise level in the room containing the source of noise needs to be reduced.

Airborne sound absorption is achieved by converting some of the kinetic energy of the air molecules into heat. This happens through friction on the contact surfaces of fibrous or open-pored foam materials into which sound waves can penetrate. However, other designs are also in use, such as chamber, foil and resonance absorbers.

The absorption is highly dependent on frequency. Generally it is true that the lower the frequencies to be dampened, the thicker the absorption material must be.

The effectiveness of sound-absorbing materials is measured, among other methods, by the degree of absorption α, the ratio of absorbed sound fraction to the incident sound intensity.