CHAPTER 1
1. Four Questions
2. You’re working on a budget , after all
3. Controlling the Acoustics
4. Room Arrangement
5. Early Reflection Points
6. 50 Percent Rule
7. Bass Traps

50 percent Rule

When it comes to optimizing the acoustics in a
room, you don’t want to deaden down everything. You want a room that has ambience to it, otherwise what you record and what you hear won’t be accurate, and your finished recordings will suffer. Every room is different, but applying a 50 percent rule is a solid launching point.
In a square or rectangular room, I’d recommend
covering 50 percent of the surface area. For example, do one-foot by one-foot pyramid foam squares in a checkerboard pattern on every wall — cover your 50 percent that way. And it counts on the ceiling, too. 50 percent would be great, but if you can’t do that, make sure you get that early reflection spot. It will knock down the reflections to a degree that they won’t get in your way and cause monitoring issues.

You just need to remember, when you’re recording in a home studio, and you’re recording
drums in a bedroom, you have all these early
reflections that are going to bleed into every
microphone and create unpleasant anomalies
like comb filtering or flutter echoes. If you have
a room with parallel walls and you take a super
ball and you whip it at the wall, it’s going to go
‘bounce bounce bounce’ back and forth —
that’s a flutter. And if you clap your hands in a
live room, you can hear a flutter. That can kill a
recording. That’s why we do the acoustic absorption on the walls, to cut that flutter down.”

Bass Traps

Sound bounces back and forth between hard,
parallel surfaces, and lower frequency sound
waves are longer than high frequencies. For instance, a bass guitar playing a low E @ 41 Hz
produces a wave roughly 27.5 feet in length,
while a piccolo playing at 3500 Hz produces a
wave that’s less than four inches long. Acoustic
foam effectively absorbs reflected sound, and
thicker acoustic foam is better at absorbing low
frequency sounds.
The panels and wall hangings used to absorb
the early reflection points are going to help with
the mid and high-mid frequencies, but when it
comes to preventing lower frequencies from reflecting and causing cancellations and boominess in your recording/listening environment, using bass traps and denser sound absorbers behind your monitoring point is recommended.

Since low frequency resonances have their points of maximum (or minimum) pressure in a room’s corners, bass traps are often triangular in shape to fit into corners, though studio gobos are also common for lower frequency absorption as well.

Remember, once the sound has passed by your
ears, soaking up the sound behind you is critical
so you won’t be coping with sound reflecting
from behind you.

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