High fiber density and generous surface area drive porous material absorption

Evidence

Another form of energy loss occurs when the sound wave hits or travels through some porous material. In this case there is a very large surface area of interaction in the material due to all the fibers and holes. There are frictional losses at the surface of any material due to the interaction of the velocity component of the sound wave with the surface. A larger surface area will have a higher loss, which is why porous materials such as cloth or rock wool absorb sound waves strongly. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 344 (#corroborates, via linked claim)

Categorization

• XREF: connects to: Fiberglass density barely affects absorption but strongly affects mechanical strength — Toole, Floyd E, Sound reproduction- the acoustics and…, 1370; Dense wall fabrics with empty space behind them become unwanted absorbers; Porous absorbers damp sound through velocity-induced frictional losses — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2046 (+1 more)

Broader Connections

• Porous materials absorb sound because their large surface area creates frictional losses. #corroborates (0.85) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 344