Recording Basics – Room Acoustics (Ears Part 3)

In a domestic environment, aiming to get something like a “flat” response curve is nearly impossible. It is something that involves huge costs and has very little returns after a given point, so instead, let’s try to tame the really big problems.

Avoid symmetric measures

Beginning by the simple stuff. Symmetry is evil. No, really, it is. If you are inside a room where you have flat walls facing flat walls, and flat ceiling facing flat floor, without any furniture inside, that’s probably the worst possible scenario to deal with.

A simple answer is: add furniture. A couch. A nice bookshelf on one of the walls. Maybe a decorative panel made of soft material on another. But keep things RANDOM. Do not go covering all your walls with foam, cloth or any other similar solution, because that will only make the problem worse.

If we remember the sample I gave before, the photographic workstation against the sunlight. Which do you think would be the best approach to fix the problem: Changing the light bulbs of the ambient? Changing the color of the walls? Sunglasses? Placing mirrors to reflect the sun?

“Of course not, duh…” You will say. And you are right! There are about two obvious things that you can do: First, move the damn station elsewhere. Second, just block the light. Block. Not correct, not trying to diffuse and recombine to make the most amazing solar lighting system ever seen.

FIX the most relevant problems

So why when working with audio would you want to take the prior approach? Using EQs to fix room response? Trying to tune the room, trying to do all kinds of stuff to “live” with the problem?

The first thing to do is to find out where the sun is hitting directly, and just avoid it.  Take a simple recorder (a cellphone for example) and go around the room, clap your hands, speak, and find out where you can hear most influence of the acoustics.

Reverb is fine, it’s necessary, you don’t want to get rid of natural reverb. You are looking for ringing, exaggerated reverb and changes in the midrange: muffled or nasal for example.

Usually the worst places are close to walls and corners. So it’s a good idea to place your workstation at a relatively good distance from those. But do the test, and figure where the effects are least pronounced.

Next, let’s just block as much sun light as possible. To do so, we need to absorb the sound, over a wide range of frequencies (broadband), and we are going to place those absorbers on the corners of the room. The most critical places are the 8 points where walls meet ceiling and floor.

Broadband Absorber Framework

There are recipes to construct broadband absorbers on the net. Don’t use mattress, foam, or cloth. The materials you need have higher densities like rockwool. It’s relatively cheap to build panels and hang them on the corners, and will really improve your work conditions. Probably you can keep the cost within $200.

Wood frame, mid density rockwool inside, cover it with fabric to not look so awful and to not expose you to the fibers of the material, hang it on the corners, and it will block most of the nasty problems of your room. Improving the conditions of everything audio related.

This is not only a great idea to work with recordings, but also in a study place for any musician, since hearing what you are doing accurately will improve your learning process.

What to NOT do

– Cover walls and ceilings with foam;

– Waste time calculating variables and frequency responses without addressing the critical problems;

– Trying to correct problems of the room by using software;

– Try to correct it by using some kind of room correction equipment (the sunglasses);

– Buy some magic acoustic device sold by hi-fi stores that promises incredible results (aka snake oil);

– General use of money instead of brains. If you want to use money, pay someone who knows what he/she is doing.

Room Acoustics Solution for home

– Broadband absorption on the corners;

– Position your workstation;

– Avoid symmetry.

And this concludes this crucial subject of room acoustics. It’s not such a complicated problem to solve, but it should not be seen as an improvement, it is a requirement.

Useful resources:

A recipe to construct your own Broadband Absorbers

A thread on the Reaper Forums about Acoustics