Soundproofing and Acoustic Treatment (Part 1 – Soundproofing)

Hi, this is Justin from Sonic Scoop, coming at you from Joe Lambert Mastering.

A few weeks back, I did a post about the most essential equipment I have in the studio, and for me, the number one most important piece of equipment in your entire chain is your room. The space you’re in.

Obviously, it’s going to affect how you’re going to hear things, it’s going to affect what your speakers are going to sound like, and it’s going to affect the sound quality of every single thing that you record.

So a lot of people are interested in making their rooms sound better. I get a lot of questions about this. I’ll get e-mails from people who are building their room for the first time and saying, “Okay, I’m ready to kind of do this for real, I want to do some sound proofing, so I was just wondering if you could tell me what kind of foam I could get to put on the walls that’s going to sound proof the room?”

Then I just have to resist doing the whole face palm. It’s very hard but I do because it would be rude. You never want to face palm when someone is asking you sincere questions, it’s just bad manners with that level of the face palming.

So I instead tried to be helpful, and the way to be helpful is to kind of educate people, and you know, this is not something that we learn in a high school. We don’t learn how to sound proof a room, but I will say there are a lot of misconceptions about it.

So I want to kind of demystify some of those. There are two broad categories we’re going to be talking about. There is sound proofing, and there is acoustic treatment, and they are two very, very different things.

When folks ask me about sound proofing their room, what they really mean is keeping sound from outside from getting in, and usually even more importantly for most people, stopping the sound from getting out so that they don’t have family members and neighbors trying to wring their neck at all times like they are Bart Simpson.

So that’s one. Sound proofing.

Then we’ve got two, acoustic treatment, and that is making the room that you’re in sound better. Getting rid of things like flutter echo, resonances, bass buildup, room modes and nodes, getting to those ideas in just a second.

So the first thing to get out of the way is a more complicated one — sound proofing, and I just want to set some expectations here.

I don’t want to go into extreme detail on how to sound proof a room, because we could do a whole long video series just on that, but I do want to give you a sense. Really, the only way to sound proof a room is to add mass or trapped air can also work as a cushion.

Putting up foam is not going to do it. For example, if I put some cloth in front of my face, in front of my mouth here, you can still hear me talking pretty well. You might lose a tiny, tiny bit of high frequency with the cloth in front of my mouth, but it’s not a huge, huge disparity.

On the other hand, I put my hand in front of my mouth, and all of the sudden, you’re probably hearing me much more quietly, and we’re blocking off sound much lower down in the spectrum. Right?

If my hand is in front of my face, it’s not just the high frequencies, we’re starting to block out more and more and as I add more and more thickness, we’re blocking out more and more sound.

That’s the same principle with sound proofing a room. You need mass.

Foam is only going to stop high frequencies from bouncing around within your room, but guess what? Your wall behind the foam? It’s already blocking those high frequencies anyway. Adding foam to it isn’t really going to block any more.

All of the frequencies below a certain point are still getting through that wall. So what do you do? Well, the most simple thing to do would be to take up one layer of drywall, and add another layer of drywall to it, and that could be helpful.

But that’s not really enough. What you really want to do is make sure those two walls are decoupled from one another so that the vibration isn’t going from one wall into the other and just continuing onwards.

Thickening a wall, it can help a little bit, but really not enough. So the ideal here is to build a room within a room.

So if you have a piece of drywall here, you’re putting another piece of drywall next to it with an air gap. If you’ve got a ceiling, you’re dropping a false ceiling below it. On your floor, you’re floating a floor above it.

Now of course if you live in a basement, you might not need to block off the floor with a second layer. If you’re in a top floor of a building, maybe it’s not a big deal and you don’t need to drop a ceiling, but that’s the idea is you’re building a room within a room, and as much as possible, decoupling these walls from each other.

That way you have extra mass and trapped air in between. Yes, you can lose a little bit of cubic footage in the room by doing this, but it really is the only way to stop sound from getting in and out of a room.

Now, of course, there are better and worse ways to do this. Some materials are great at blocking sound. I mean, if you have a wall that’s made of brick, or cinder block, that’s fantastic. If you’re using drywall, one thing you can do is you can have the two pieces of drywall, but even better, you can have a double piece of drywall here, and then a single piece of drywall here with some trapped air in between. The double piece of drywall and the single piece of drywall will have different resonant frequencies, which will actually help block more sound from getting in and out.

It’s a bit more of an advanced idea, but two pieces of drywall the exact same thickness, it’s just like two drum heads tuned to the exact same frequency. They vibrate together.

But if you have two different walls of two different thicknesses, say a double wall and a single wall, they don’t vibrate at quite the same frequency, and that can help with sound proofing even more.

But that’s the basic idea. Building a room within a room. There isn’t really a half-assed way to do this. You’ve kind of got to do all or nothing to get decent results, but with that said, another thing you could do if your walls are already nice and thick is you can focus on your weakest points, because a sound proofing job is only as strong as its weakest points.

I mean think of this, you’re standing outside a club, all the doors are closed, all you hear is maybe some bass getting through that club.

As soon as someone opens the door, oh my goodness, it feels like you’re in the club. It’s crazy loud. They shut the door, and you’re back to just hearing nothing but bass again.

Same with a car, right? Someone is blasting some tunes in their car, you hear nothing but bass, they open their door, the whole thing comes gushing out, they close the door, you hear nothing but bass again.

That’s because sound is kind of like water, right? If you fill up a jug with water and you poke a hole in the bottom, the water is going to come out of that hole. You poke a hole in the side, the water is going to come out of that hole.

Sound is the same way. Anywhere sound can go it will go. So if you have nice dirty walls, but you have a very thin window, sound can get in and out of that window. If you’re like some apartments here in New York City, you might have decent plaster walls, but there’s a door going out into the hallway, and that door is practically made out of two pieces of cardboard, and you can hear voices right through it.

Upgrading that door with a solid core wood door or if the frame can support it, a steel door filled with sand. Something really thick, making sure there’s no air gaps around that window or door, that can help.

These are things you want to keep in mind when you’re doing your own soundproofing job if you decide to go the full Monty and really sound proof, that your sound proofing job is only going to be as good as the weakest links.

I have a couple of articles detailing how to sound proof a room. I kind of sketch out plans, ways of doing it, and one of my friends and a fellow writer and editor Blake Madden actually picked up one of my articles and used it to build an entire room for rehearsing with his band out in his place in Seattle.

He wrote an article about the experience of taking just someone else’s article and building a room based on it.

I was surprised that it worked, but it did. So I encourage you to check both of those out. You can find links for them below.

One important thing to remember when you’re building a room within a room is you want to allow for appropriate ventilation. Otherwise we’re really making something air tight, which is what works well for sound proofing, but air tight can kind of make you pass out once all of the carbon dioxide coming out of your mouth overtakes the oxygen, and not good.

So you definitely, definitely want to have a ventilation system in place, and that is a crucial component to building a room within a room.

So that sound proofing. How much does it cost to do a job like this? Well it depends on how do-it-yourself you are, how much you have to rely on outside contractors, but I would say at the bare minimum, a couple to a few thousand dollars will help you build out a room and get a reasonable amount of sound proofing if you’re looking at just doing your weakest links, your windows and doors, maybe a few hundred dollars per window or per door at minimum may help you if you can’t do a full build where you are.

So that is sound proofing in a nutshell. Topic two, room treatment. Making sure that room sounds good.

Sonic Scoop

Sonic Scoop

Sonic Scoop is a website all about creative music and audio production. We've partnered with them to feature some of their awesome videos on The Pro Audio Files.
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