ABSORPTION

Absorption of sound is probably the most commonly misunderstood function in acoustics. The scenario usually goes like this...

"I'm trying to keep the noise from our factory floor from comming through the walls and ceiling of our adjacent office. I covered the factory side walls with "Sound Proofing" panels and layed 12" of fiberglass across the back of the ceiling tiles in the office. It made no appreciable difference."

Here's why:

Acoustic absorbtion panels are used to reduce the amount of sound that is reflected from a surface. These panels do very little to decrease the amount of sound that travels through a structure.

The amount of sound that travels through a barrier or wall is a function of the mass of the barrier or wall. Fiber glass or foam panels are typically very light (1 to 7 pounds per cubic foot). So, if your wall is made of wood or metal studs with one layer of 5/8 drywall on each side and insulated in the cavity, you'd be much better off adding an additional layer of drywall to each side than adding an absorber.