Acoustic Foam - how it works

Acoustic foam explained

Acoustic foam works by absorbing sound which then will spontaneously convert part of the sound energy into a very tiny amount of heat in the the absorbing material it comes into contact with, if it was to hit a more reflective surface rather the sound would continue after being transmitted or reflected.

Acoustic foams properties

Acoustic foams are porous absorbers, they are specifically formulated open cell foams with specific physical factors shown below the foam can be made from either polyester or polyether chemical foam formulations. Absorbing noise by friction within the cell structure of the foam. Open cell acoustic foams are a very highly effective noise absorber across a broad range of frequencies expecially effective on medium to high frequencies. Most open cell foam foam falls into two manufactured groups both are polyurethanes, one is polyether and other is polyester differing foam manufacturers make with differnt methods but both make foams formulated for acoustic applications, To be sure you are getting a acoustic foam look for NRC data on the foam that is accredited as being a specifically formulated acoustic foam, some polyester foams are packaging foams and would be totally unsuitable for use sound absoption also polyether foams that are not specifically formulated for acoustic applications are unsuitable such as those grades of foam that are used for bedding and upholstery. The only way to be certain that a foam is suitable is to have the the NRC (noise reduction coeficient) data for the foam and more specifically for the individual tiles and / or acoustic foam bass traps, the data shouls show the results across a full frequency range being tested. The physical properties of acoustic foam both polyester and polyether, are quite specific as they are needed to give the optimum acoustic absorption. The exact absorption of porous open cell acoustic foam is determined by a number of factors such as the following :

• The foams cell size
• The foams cell structure
• The foams thickness
• The foams hardness
• The foams density
• The foams torosity
• The Foams porosity

Shown below an acoustic foam Corner Bass Trap