Editing Soundproofing (section)

====Porous absorbers====
Porous absorbers, typically open cell [[rubber]] foams or [[Melamine foam|melamine sponges]], absorb noise by friction within the cell structure.<ref>{{Cite book |last1=Cox |first1=Trevor J. |url=https://books.google.com/books?id=f19_6NFg4jkC&q=Acoustic+absorbers+and+diffusers:+theory,+design+and+application |title=Acoustic Absorbers and Diffusers |last2=D'Antonio |first2=Peter |date=2009 |publisher=CRC Press |isbn=9780203893050}}</ref> Porous open cell foams are highly effective noise absorbers across a broad range of medium-high frequencies. Performance can be less impressive at lower frequencies. The exact absorption profile of a porous open-cell foam will be determined by a number of factors including cell size, [[tortuosity]], porosity, thickness, and density. 

The absorption aspect in soundproofing should not be confused with sound-absorbing panels used in acoustic treatments. Absorption in this sense refers to reducing a resonating frequency in a cavity by installing insulation between walls, ceilings or floors. Acoustic panels can play a role in treatment reducing reflections that make the overall sound in the source room louder, after walls, ceilings, and floors have been soundproofed.