Quick & Dirty Room Treatment

[lfh]

Here´s more on the Q&D theme:

My Swiss Cheese Corner Traps (TM)! The boxes are to be filled with e.g. Owens Corning 703 and wrapped with thin fabric that is glued to the cardboard. No other tools than tape, scissors and glue needed. Remember where you read it first

I think rectangular cutouts is the way to go (more absorber area exposed), but being half-Swiss I consider it an act of patriotism to drill the holes -- or maybe it was just the fun of it. Bzzzt! Bzzt!

[lfh]

Porous absorbers are not very efficient at low frequencies, since they for manageable sizes only constitute a small fraction of a wavelength. The standard trick is to gap them, i.e. place them at a distance from the hard wall. The absorption of this kind of device is mainly due to frictional losses, so the maximum impact is achieved when the absorber is positioned at spots where the particle velocity of a standing wave has it maximum magnitude, e.g. at a quarter wavelength from the boundary (zero velocity at the rigid boundary).

In the corners all modes have pressure maxima, so for broadband attenuation it would be best to put membrane-type absorbers here. Short of that, massive porous absorbers can be placed across the corner for at least fairly efficient broadband absorption. Since I happen to have lots of rockwool and a bunch of cardbord boxes, that´s what I´m using

[Hoerninger]

Are these boxes from IKEA?
___________
Peter

[lfh]

Are these boxes from IKEA?
___________
Peter

Nope, but I might in fact switch to IKEA boxes. Tomorrow I´ll look around for larger boxes. Ideally I don´t want to mess with cutting the rockwool (that´s almost too dirty even for Q&D), so boxes where I could fit 600 x 900 mm slabs would be nice.