Summery: There is a lot of confusion about acoustic treatment in rooms. I’m not talking about how to do it but why you should do it. I decided to do a very short post on my perspective. With a bit of luck this should illuminate the real reasons for room treatment and why it’s important.
The Real World: Here is the argument: In the real world no one listens to music in ideal environments. There are bass-hyped consumer headphones, mono PA systems, earbuds, bad speakers, and bad rooms. So why spend the time and money getting your room perfect?
First, there is no such thing as a perfect room. No one mixes in anything close to a room with a flat frequency response. Here is an example from realtraps.com. Realtraps makes quality acoustic treatments and has lots of useful information on their site. I have no affiliation with them.
The purple line is frequency response after treatment. The red line is before treatment.
If you haven’t done one of these tests before I’ll try and break it down. You play a test tone through your speakers into your room. The tone is at a constant level. The tone starts low and sweeps up in frequency. For example from 10hz to 1khz. It kind of sounds like a slide whistle. A microphone (typically at your listening position) records the tone. The software usually compensates for the non-linearly of your speakers and your test mic. Then it spits out a graph. This lets you know how jacked you are.
On the above graph the Y axis (vertical) is level in decibels. The X axis (horizontal) is frequency. In a perfect room you would have a horizontal line at the level of the test tone (In this graph it was probably around 67dbs).
The dips and peaks here are due to the room! You may be shocked to see the room can cause a deviation range of 30db. I was. Imagine turning a fader up or down 15dbs in a mix. That’s a lot.
Back to the point this graph illustrates. There is no perfect room. What you do with acoustic treatments is take a bad situation and make it a workable one. You make a 30db deviation range (red line in graph) into a 10db deviation range (purple line).
It’s Not About You: So you treat your room. Now you can hear things you never heard before. The bass is tight. The stereo field is clear. Now you can mix. Now you like the sound. But how you hear and how your room sounds isn’t the bigger point. It’s about how well it translates outside of your room. Here’s how I think about it.
Relationships: What should a good room do? Should it eliminate first reflections off of walls? Yes. Should it control room modes? Yes. Should it minimize comb filtering? Yes. But underlying all of these is one common goal. You want to accurately judge the relationships between the sounds you are mixing.
Here is an example. You have a very simple mix that consists of 2 tracks. Track one has a sine wave at 200hz. Track 2 has a sine wave at 500hz. You are working in a decent room and judge this mix sounds best with both levels at -6dbs. So the level relationship of the tracks is 1:1.
Now you decide to mix it again in a very bad room. This time you are sitting in a null at 200hz. Null = place where a certain frequency cancels out. In reality it’s just greatly reduced. This looks something like the 130hz marker on the above graph.
The 200hz is still at the same level but you can’t hear it. So you raise it 12 dbs. Now the relationship between tracks has radically changed. Instead of the levels being 1:1 they are, for example, 1:4. The math isn’t important here. What is important is the way the relationship has been distorted between tracks. That distortion, that changed relationship, will follow your mix where ever it goes… the club, earbuds, or an audiophile quality living room.
To recap: You treat the room to better judge relationships between sounds. If you get the relationships right the mix translates better everywhere.