Acoustic treatment can seem daunting, especially if you’ve just started recording at home. What can you use for treatment? Where in the room do you put it? And how do you know if your recording space even needs treatment?
These are all questions we’ll answer in this easy-to-read beginner’s guide to treating your home studio. They’re questions we’ll need to answer to help you get the best recording possible.
A great mix, a great master, and a great overall song starts with the engineering process. And acoustic treatment is a crucial aspect to capturing beautiful recordings.
Why is it so important? Well, in an untreated room, sound can appear distorted. Sound waves leave the monitors, bounce around the room, and and make the music sound inaccurate by the time it reaches your ears. Some sounds will appear too loud, others too soft. And that makes mixing accurately almost impossible.
You might have a great ear for mixing, but if you’re in an untreated room, that doesn’t matter. The sound you hear will be off and, ultimately, your mix will be off.
So let’s talk about acoustic treatment…
How Does Sound Move Around The Room?
Before we jump into treating your recording space, it’s good to know how sound travels.
When you make a sound (sing, strum a guitar, etc), the soundwaves move from the source outward in ever direction. Some of the sound moves in a straight line into the microphone — this is called “direct sound.” The rest of the sound ricochets around the room randomly, many of those soundwaves inevitably returning back to the microphone — this is called “reflected sound.”
Now, because direct sound goes directly into the microphone without bouncing around the room, it’s the most accurate sound the mic can capture. But with reflected sound, each new wave of it can change how your recording sounds, even if only a little.
Depending on the size and shape of your room and whether or not you’ve treated it acoustically, the change in sound can be drastic. Typically, bigger rooms are better because the soundwaves have more space to bounce around and take a lot longer to get back to the mic, if at all.
Most likely, you don’t have a huge room with high-ceilings. So now you’ll need to figure out if your room needs treatment, what kinds, and how much.
How To Know If Your Room Needs Acoustic Treatment
Before you decide what acoustic treatment materials to get, you’ll want to test the sound of your room. You may have heard of the “clap test.”
This is where you walk around your space clapping as loud as you can. Go to every corner and wall while doing this, listening to the reverb. Does it sound tinny or bassy? Where is it more pronounced?
Smaller rooms will probably have high-pitched, short ringing sound. Larger rooms usually have a nice full reverb. The more of a ringing sound you hear, the more absorption you’ll need — this will make it sound dryer, which is good. You can always add reverb with plugins, but you can’t remove natural reverb from the recording. The larger the room, the less treatment it will need in general.
It may help to do the clap test in other rooms so you can familiarize yourself with the different sounds. Try it in your rich friend’s mansion. Go into your bathroom and clap. You’ll hear the difference.
The Three Trouble Spots In Your Room
When you treat your room (we’ll get to the how in a bit), there are three spots you need to deal with first: trihedral corners, dihedral corners, and the walls.
Trihedral corners are where the walls meet the ceiling and the floor (two walls + ceiling = three surfaces AKA trihedral). Dihedral corners are where the walls meet each other (two surfaces AKA dihedral).
The general rule is that trihedral corners get top priority, dihedral corners get second, and the walls get third. The reasoning behind this is: if there are more surfaces that meet in one place, then there are more surfaces for soundwaves to bounce around on.
Acoustic Treatment 101
Okay, now let’s get to the what and how of acoustic treatment.
The main elements involved are absorption and diffusion. These two methods of acoustic treatment help to reduce reflected sound, leaving more of the direct sound (source-to-mic sound). This gives you an overall better recording.
And the four main types of treatment that deliver absorption and diffusion are bass traps, acoustic panels, diffusers, and vocal reflection filters.
Bass traps are the first thing you want to use when treating your room — they’re mainly useful during the mixing process. They can be somewhat expensive, but they can make a huge difference. These “trap” lower frequencies (hence the name), but they can also absorb some mid-to-high frequencies too.
You’ll want to put the bass traps in the trihedral corners of the room, which is right where the bass likes to build up before bouncing back to the mic. You want your bass traps to be tucked snugly into the corner with no space behind it.
Next, you should use some acoustic panels, which help reduce the mid-to-high frequencies during recording and mixing.
The first place to put them is right behind your studio monitors. Then you’ll want to hang them along the dihedral corners of the room, leaving a little space between the panel and the corner. This helps them absorb a tiny bit more low-end.
And then you should hang the rest of the acoustic panels on the walls. A good place to start is on the walls on either side of your ears and the wall directly behind you. Try to spread them out evenly, using opposite patterns on parallel walls.
Diffusers are mainly for bigger rooms and not always necessary in smaller rooms. Most home studio producers have smaller rooms (oftentimes with natural diffusers like a bookshelf, a dresser, and a bed) and smaller budgets (diffusers are expensive).
But if you do have a big space and some extra money, you can place diffusers on the top sections of the walls and on the ceiling.
Vocal Reflection Filters
If you do have small recording space, a vocal reflection filter can go a long way. This is that semi-circular contraption you may have seen that sits behind your vocal mic.
The point of it is to absorb soundwaves as soon as they leave your mouth, in turn reducing the amount of reflected sound bouncing around the room. It does basically the same thing as acoustic panels, it’s just catching the sound as soon as possible.
Acoustic Treatment Alternatives
DIY Sound Treatment
First, if you can’t afford a vocal reflection filter, you can use things you already own, like a blanket hung from a doorway, a mattress stood up against the wall, or a closet full of clothes. Just position the mic about 6-18 inches away from the makeshift absorber and that should help.
You can also use thick blankets to line the walls and put small pillows behind your monitors.
Another trick is to use dynamic mics, which are usually less sensitive than condenser mics. This means dynamic mics are not as affected by reflected sound, although they may not sound as pretty as a condenser.
Basically, it’s better to make your recording space as dead-sounding as possible and get as much direct sound as possible. You can always add reverb later with a simple reverb plugin.
Room Treatment Software
Did you know those headphones you’re mixing with may color the sound you hear? Your monitors too.
That’s why you may want to consider a room treatment software like Arc or Sonarworks. For example, Sonarworks removes the coloration from your headphones and/or monitors, meaning you get the most accurate sound to begin your mix with.
It strips away the lies your headphones feed to you. And if you want to ensure your room is not distorting your mixes, a room treatment software can really help.
Whatever you end up doing, please do something to make your room and recordings sound better. You won’t regret the little time and money it takes.
Caleb J. Murphy
Caleb J. Murphy is a songwriter and producer based in Austin, TX.