ACOUSTIC ABSORBERS, are they really useful?

This article is for those who listen to music through room speakers and musicians practicing with their instrument.

Physics: the sound waves from speakers spread in all directions, mainly out the front of the speaker, but at a wide angle. Some of these wave reach your ear directly, but much of the energy is reflected off hard surfaces (walls, floor, ceiling) and reaches your ears out of phase (later) than the direct output from speaker to your ear. This will smear the sound and and cause tinny echoes too. {I used to thing this is what music from a stereo sounded like}.

There is usually not much that can be done about the dimensions of the listening room, but the surfaces can be altered to absorb much of the random sound reflections.

Initial reflection points are estimated based on the location of the listener in relation to the speakers. There are first reflection points to each side, behind, below (floor) and above (ceiling) the listener. AND behind the speakers {exception includes some speakers that radiate backward as part of their design}.

The side points are estimated by having another person pass a mirror at the listener’s head level along both sidewalls. When the listener can see the speaker on that side on the mirror: that is the point. An absorber goes there. The floor can be handled by a large rug or carpet, a large absorber on the wall behind the listener will take care of that area. I did not put anything on the ceiling, but put a couple smallish absorbers higher on the back wall.

The absorbers behind the speakers are the most effective for cleaning up the audio and should be the full size of the speaker and mounted on the wall. I like to have the speakers about 12-15 inches out from the wall.

My absorbers are two inches thick and were DIY, of course, but they can be purchased commercially. I think I used Owens Corning 703, but Roxul is said to be just as good and less expensive. I have six of various sizes.

This is the way I did it. One can be much more the engineer if desired, but don’t put up too many of these or it will deaden the room.

Oh, do they improve sound quality? You bet they do!!IMG_2731IMG_2733


references: Audio Karma–>listening spaces

ATS Acoustics (where I bought my supplies and sell completed absorbers too), other commercial operations


Many You Tubes about room acoustics, making your own panels, etc.


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