Recording - March 2015 - 12

Trying to figure out what room acoustics is all about, determining what truly good practices are, and making sense of all
the information flying around out in the world, is a daunting
quest. Many have tried, and many have died...
Well, not really, but it's still a difficult task, and finding good,
reliable information on room acoustics can be an overwhelming
challenge. There is a breathtaking amount of poor or downright
false information floating around, much of it from sources you
would expect to know better. And there's a charlatan lurking
behind every corner.
This article will clear up a lot of it for you. Quick hint: it's not dark
arts, magical alchemy, or abusive and debasing rituals meted out
by mythical beings with really bad tempers. It's just physics.

days, you are dealing with a highly collaborative creative
process, where your work will be played in a great number of
rooms during its genesis.
So to ensure that what you're hearing is what's actually on the
track, and that each person during the process hears what you
intended, it is very important that each of the rooms be as neutral as possible. The room must add little or no coloration to the
sound, and every detail must be heard. Each set of ears needs
to accurately hear what's really there, avoiding each successive
room's sonic signature, in order to make accurate creative decisions. And in the case of sound for motion pictures or television,
the last thing any sound editor wants is a phone call from the
mix stage saying something's wrong!

Basic Acoustics:
By Bruce Black

Five Big Problems, Four Excellent Tools
Get a grip on what your room is doing to your music

Why bother?
The big question is -why mess with all this complex and difficult acoustical stuff? You just get the best speaker you can
afford and you're guaranteed good sound, right? Wrong.
It can be said that a speaker is actually a sum of two parts.
The first part is the speaker itself, with its cone, cabinet and all
that. But the other part is the environment in which the speaker
operates-the room acoustics. And bad room acoustics can
make even the best of speakers sound like poop, and mislead
you terribly about what your tracks really sound like.
It takes some time and effort to get a critical listening room
properly decked out acoustically, but done properly, the payoff
will be finer detail, amazing accuracy, more faithful response,
and solid localization. So the answer to why bother? is twofold.
First, as an entertainment consumer, listening to music, a movie,
or a television show is an emotional experience. You want to enjoy
the experience, with the emotional journey taking all the twists and
turns you expect from it. A poor quality sonic experience will be
distracting and pull you out of the experience. So good acoustics
creates an experience that is emotionally satisfying.
There is another area where good acoustics are essential. In
the magical world of creativity and content creation, it is important to know exactly what a song, video, or other artistic effort
will sound like in other rooms. In other words, this knowledge
helps you control the experience of your audience. In the case
of motion pictures and television, and perhaps even music these

What can go wrong? Meet the Bad Five
There's a comedy group from the 1970s called The Firesign
Theater, who did an album called Everything You Know Is Wrong.
That title could also be applied to common knowledge about
acoustics, much like when people used to insist the world is flat
("hey, all you have to do is look at it"). So take everything you've
heard about acoustics on the street or from the guitar pick salesperson at the music store and put it aside. It's most likely wrong.
Problem #1: Skewed Symmetry
Let's say your control room has an exposed wall to the left of
your speakers and drapes on the other, with your speakers in
between and off to one side. This arrangement is not symmetrical.
You have hard reflections on your left, some absorption on the
right, and uneven distance to each wall. The disparate wall surfaces and distances unevenly change what you hear in different
positions in the room. So if you move around while you're listening, the sonic quality will change inconsistently and unpredictably.
It is best to make a listening environment symmetrical in the
horizontal plane. This means that as you sit in front of your
speakers, they are centered in the room. It's perhaps not always
possible in a home studio, but important to do as well as can
possibly be done.
This also means the acoustical treatments on the walls to your left
and right should be a mirror image of each other. And on the front
and back walls, the treatments need to be placed symmetrically on

1. What you hear at your listening position is a combination of direct sound from the speaker (left) and reflections from
side walls (center), leading to interference that can affect the tonality of what you hear (right).
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Recording - March 2015

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