[DIY]-Sound Obsorption Project

[Hi-5]

Since my stereo room has no carpet and the paint on the wall is pretty hard, i decided to make something cheap to absorpt sound.

Material:
1 piece of foam(about 2"x96"x24"), $7.79 from HxxxDepot.
1 piece of soft cotton, $2.38 from WxxMart.
1 piece of cloth, $7.59 from WxxMart

all the above were cut into 4 equally.

Step 1: cover the foam with a piece of soft cotton to increase the efficiency of sound absorption.





Step 2: then cover with the other layer, cloth.

[Hi-5]

Step 3: put them on the wall opposite to where my speakers are.

[ThomasW]

A rather unique approach to this task.

Did you check the absorption coefficient of styrofoam before deciding to use it?

[Hi-5]

no. i chose it just because it is cheap and i did hold it near my left ear and i can feel there is a huge difference of sound volume between my ears.

[joecarrow]

It'd be interesting to see measurements of how effective it is- but it's hard to argue with how nice it looks for the price! It's probably quite nice for high frequencies, maybe less so for bass. Still, sitting so close to the back wall has a way of evening out the bass on its own.

[ThomasW]

Absorption is a function of the energy in the air being turned into heat when the particles in the absorber vibrate. This is why fibrous materials like fiberglass batting, thick dacron/polyfill or similar materials are used.

Styrofoam isn't fibrous nor does it contain flexible materials, so when you place it between your ear and a sound source it's blocking certain frequencies not absorbing them.

[---k---]

It's probably quite nice for high frequencies, maybe less so for bass.

Hate to be a party pooper, but that would be my guess too. You're only getting absorption from that thin piece of cotton and the fabric. I would guess it does nothing for the bass and likely even midrange. But, if there is little to no absorption in the room, it probably does make a noticeable difference. I always refer back to Bob Golds' site for anything acustical treatment wise:

http://bobgolds.com/AbsorptionCoefficients.htm

I wonder if an easy mod you could do that may help some would be to core out the foam in the middle or in some areas to let the sound through to the wall. As you can see from Bob's charts, insulation held 16" off the wall is significantly more effective then on wall placement. Even 4" off the wall is much better. The suggested mod won't get you there, but I wonder if it would help. You could even try stuffing the holes created with more of that cotton fabric.

[jkrutke]

I use DIY 2x4 panels. I got the 4" thick, 12" square tiles from foambymail.com. They are glued to a board which is glued inside a wood frame. They work really well. I once took a measurement of a speaker 6" away from a wall, (ewww, ugly) then slid this panel behind and took another measurement. Wow, much better. The reflection nulls and peaks were greatly minimized. Someday I may do fabric cover versions that look better. These are pretty much functional only. (read: ugly)

When I do infinite baffle measurements, I lay one of these panels on the floor in front of the baffle.

[Hdale85]

I think that stuff looks neat :B

[Dennis H]

I think Ryan has the right idea. Without tearing them apart, you could cut a big hole in the middle, from the back, removing all the foam there but leaving the cotton and fabric. Then cut a piece of soft foam like a mattress pad or whatever and slip it into the hole. Your styrofoam would then just act as the frame.