Recording Studio - Soundproofing the Windows

I'm working with a friend to work on his Music room. It is in the basement, so that's the good part, however, he has 2 big windows (2' x 4') in it that the sound travels through pretty well. What kinds of things can we put over the windows (don't need the light) to block the sound. This is a rental property, so we can't do too much to the windows.

I checked some foam squares for Noise Absorption, but that is just for preventing reverb and echos of sound, not preventing sound from going through it. Maybe a few layers of dense cloth of some sort will work?

I read a few resources online and they all say that dense, heavy things work the best for blocking the sound. Any ideas?

[51m0n]

Originally Posted by metallinostheos

I'm working with a friend to work on his Music room. It is in the basement, so that's the good part, however, he has 2 big windows (2' x 4') in it that the sound travels through pretty well. What kinds of things can we put over the windows (don't need the light) to block the sound. This is a rental property, so we can't do too much to the windows.

I checked some foam squares for Noise Absorption, but that is just for preventing reverb and echos of sound, not preventing sound from going through it. Maybe a few layers of dense cloth of some sort will work?

I read a few resources online and they all say that dense, heavy things work the best for blocking the sound. Any ideas?

Auralex do a very heavy duty membrane that is for isolation. If you sandwich that between three layers of plaster board (gypsum) made to size, with some form of airtight draft exclude seal on the inside of the window that would cut out a huge amount of sound (and light )

Read their acoustics 101 pdf (download from their website) Its a hugely impressive read.

[hunta]

I would check out the gearslutz.com forums as well, they have tons of info about various acoustic treatments and soundproofing options.

[topper]

I'd try the simplest (and least expensive) approach first and if that doesn't work, step it up.

Get a piece of plywood (1/2 or 3/4" thick) and cut it so it is a hair smaller than the window. Wrap the plywood with two or three layers of blankets. Shove the wrapped plywood into the window frame.

[DocBop]

Make a bogo to go to hang over the windows. Use i-bolts and screw in hooks so it can be removed later and filled in easily. If you make them nice you can hang on wall when not recording. If would use some 1/4" plywood, foam or insulation, burlap. I would put something on the back too so it will absorb a little, but more important help avoid rattles.

[Dave Martin]

Topper's idea is nice - remember, though, that what stops vibration is mass. I'd start with the 3/4" plywood that he suggested, with caulking if necessary to make it airtight in the window frame. Personally, I'd back that with multiple layers of sheetrock - if the window glass is inset 3 inches into the wall fill it up with sheetrock (since sheetrock is cheaper then plywood). The other thing is to make the window coverings air (and light) tight. If air or light can get through, sound can get through. You might also cover both the glass side and the room side with some nice material - the outside so that the neighbors (and landlord) don't think that you've got a broken window, and the inside so that you guys aren't looking at bare sheetrock all the time.

very cool ideas guys. Thanks for the info. That makes sense to have it air-tight. The windows are set 3" back so, it should be no problem to throw some plywood up there and then fill it in.