Sound dampening foam is not only expensive, but if you cover every wall in it you may make a room "too dead." A dead room devoid of all echo isn't the best sound, just as much as echos and reflections are not your friend. In many cases it sounds better to defuse the sound rather than dampen it and absorb it completely.
Take for example a frosted light bulb and a clear light bulb of the same wattage. The frosted one and it's light is much easier and less harsh to look at, whereas the clear one can be piercingly bright.
A common technique I have seen for diffusion in a professional studio is to use wood slats together that stick out or are tilted various amounts. A very good example of this is pictured below from Solar2 in Michigan.
Our poster board wall is for this purpose, to defuse sound rather than significantly dampen it. Especially behind a drummer it can dramatically lower the harshness and increase the clarity of what you hear in a room.
It looks like you can figure out how it's made right from the picture, but I have for you some tips that will make it easier, faster, and help you not screw it up.
Step 1: Measure the Wall Before You Buy
We are going to make 22" squares on the wall, the extra 6" on the long side is how we make our ripples.
Measure out how many 22" squares you need and buy that many sheets of poster board. I recommend wal-mart for this and I've looked a few places. Many places don't have enough, especially if you want colors. You can also buy twice as much and double it up for strength.
Step 2: Draw Out Your Guidelines
Use string or a tape measure to make a long horizontal line where you want the top of your wall.
Use one piece of poster board against this line and mark off every 22" using the short side of your board.
Turn your board around 45 degrees and use the short side now to measure 22" below that line and make a new horizontal line.
Put your guide markings on this line and repeat.
Step 3: Pre-crease All Your Poster Board
2. Fold an end in and line it up with your new center crease.
3. Fold the other end into the center as well.
Step 4: Attach Poster Board
1. Staple or nail down both corners of one short side, then the middle, then two more. You will have 5 evenly spaced staples or nails.
2. Now do the same on the other short side and bow it out from the wall.
3. now push down the middle and make sure it is bowing out evenly. Tack the center first, make sure you are aligned, and add two more on the outside.
4. Repeat step three with your new smaller ripple. Push carefully and evenly along the ripple so it pops in along your earlier crease without kinking anywhere.
5. Repeat step 4 for the final ripple.
You can see in the final picture that they alternate directions. If you're markings aren't square you'll discover this now.
Step 5: Throw Some Sound at It.
After your wall is complete, when you clap as you walk near it your clap should sound clearer and less sharp than before. Some say it sounds closer to you. Compare recordings if you get the chance.
If you do this to your biggest flat wall and put foam in all the corners you can dramatically change the feel of a room. If a room is treated enough everything will sound close and clear like you're in a quiet car.
A good place for foam is egg-crate hospital mattresses. The thicker the better, as thinner foam will still allow lower frequencies to reflect and make the room muddy or boomy.
Blankets are remarkably helpful, again especially think ones. Many people we know have also used actual egg crates of different materials and had that help with diffusion as well, but your whole band better eat a lot of eggs.
In conclusion, I recommend a good combination of Absorption and Diffusion to tame a room. Be conscious of flat surfaces that face each other and dampen all your corners as much as you can.
This is not the same as sound proofing because we are not building the walls to keep sound from leaving the room, just treating it while it's in there. In spite of this however a less echoy room is quieter from the outside. This is because all the echos amplify like an acoustic guitar. So although it's not ideal for that purpose, if you do this to your bedroom people outside will not hear your antics quite as loudly.
This has been Wozn from the band Rooftop Ridicule
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