Welcome to our Soundproofing Series, where we delve into the vast and mysterious world of soundproofing! And we do mean vast! There are countless aspects to consider when treating a room to make it as quiet as possible, and some of them can be quite complex. It is also just as important to keep sound from seeping out as to prevent noise from coming in, which is the other side of the coin.
The subject is so complex that it would be too much to cover in a single article. Therefore, we’ve decided to deliver the info in a four-part series on soundproofing, which should make the concepts easier to digest. The series is comprised of the following sections:
- Soundproofing Series #1 – The Theory(s) Behind Soundproofing
- Soundproofing Series #2 – Tips That Won’t Cost You A Cent
- Soundproofing Series #3 – What You Need To Know About Barriers, Absorbers, And Sealants
- Soundproofing Series #4 – Advanced Structural Solutions You Can Try
- Soundproofing Series #5 – Additional Resources On The Art And Science Of Soundproofing
You can head straight to the sections you are most interested in, but we strongly suggest that you read them in the order they are presented. This will make it easier for you to grasp the more complex topics later and ensure that you have a solid understanding of the fundamentals.
With that being said, let’s dive right into it!
The Big Myth
This may come as a bit of a shock (especially considering the title of this series), but sound “proofing” doesn’t actually exist. Sound reduction and attenuation, yes. Soundproofing, no. At least not the version most people conjure in their minds.
There are some very effective methods of extreme sound reduction/attenuation. But many require so much money, physical space, and careful construction to do it “right” that the attempt (for us mere humans) just isn’t usually a viable option. Even the largest entities who successfully push through the very costly and complex process of designing and constructing a “soundproof” space will attest that it’s a mammoth and daunting undertaking.
Thankfully, for most of us working with smaller rooms and budgets, there are several things we can do to effectively reduce the level of unwanted sound coming into and out of our studio spaces. Many of these require little or no cost, such as installing soundproof curtains. To make sense of it all, though, we first need to be on the same page about what sound is and how it travels. Then we can talk about how you can make it difficult for unwelcome noise to weasel its way in and out of your room.
What sound is and how it travels
Super quick recap: sound is produced by vibration. For instance, when a phone rings, sound energy is created. This energy moves as particles collide, forming longitudinal waves. When these pressure waves (occurring at various frequencies) reach our ears, our brains perceive them as sound. Vibrations occur in solids, liquids, and gas – including the air we breathe.
Here’s a fun little animated video I stumbled onto that does a pretty good job describing how sound is transmitted.
Riding the wave
If you search for definitions of soundproof, you’ll find various attempts to explain that if something is soundproof, it is “built in such a way as to prevent the passage of sound.” I can almost fully agree with that, but let’s be more specific. Let’s replace the word sound with vibration. So, to actually “soundproof” something means we’ve somehow made it incapable of receiving (or at least transferring) vibration. Can’t vibrate=no sound=soundproof.
But, here’s the catch: no matter how large or small something is, EVERYTHING in this universe is subject to vibration. EVERYTHING has a resonant frequency that it will vibrate at. So, it’s a pretty tall order to think we could somehow override nature and prevent that.
Here’s a video of how a gentle wind passing through the Tacoma Narrows bridge caused the huge concrete and steel structure to vibrate dramatically (at its resonant frequency), causing it to collapse.
To me, saying something is soundproof is like saying something is fireproof. But launch that “fireproof” item to the sun, and it may not do so well. So, is it really fire “proof”?
The fact is, there are various levels of soundproof-ness (not a real word), just like there are different levels of being fireproof.
If you work hard enough at making your room “soundproof,” you will eventually reach a point where you can’t hear the problem noises inside it anymore. Does that mean your room is now fully soundproof? Well, no. Just change the frequency and volume (amplitude) of the surrounding noises enough, and your room may not be quite so soundproof anymore under those new conditions. My point is this: the word “soundproof” is‒in most cases‒a misnomer and really shouldn’t be used.
I’m not trying to be facetious. I just want to be accurate. When someone (including me) suggests that you spend time or money on something–no matter how little–it’s a big deal. So I want you to feel confident and have realistic expectations following the suggestions I give in this series, knowing WHY they can help you create a more noise-free studio space for you.
The suggestions I give you won’t by themselves “soundproof” your room. But how rewarding would it be to notice cumulative improvements from the steps you take!
I’ve always thought of acousticians as basically modern-day wizards. It wouldn’t surprise me to discover there’s a hidden, magical school somewhere with a bunch of acousticians-in-training running around!
I’ve had many rewarding and memorable opportunities to associate with acousticians throughout my career, but one experience stands out in particular. Many years ago, I worked as a re-mastering engineer for a studio where a new dedicated mastering room was being constructed for me.
I had a very eye-opening “front-row” experience observing the entire process, from planning and design, all the way through the numerous phases of construction. I even sat in on the final measuring of the acoustic response of the room. What a cool journey!
It wasn’t all smooth sailing, though. One morning, I arrived as the acoustician patiently tried to explain to the HVAC contractor why the air supply ducts they had just worked on were not installed correctly.
The installers had ignored specific directions on the blueprints and had installed the wrong type of ducting in the wrong way in the wrong place. It all had to be taken down, replaced, and reinstalled (at their cost). They mounted a duct run, so it rigidly connected two walls together. But as detailed in the blueprints, the walls had to remain physically separated from one other.
I asked the acoustician if the builders were just lazy or possibly just didn’t know how to read blueprints. I was a bit surprised that he came to their defense.
He explained that although highly skilled, the installers had no prior experience with the requirements and process of building a recording studio space. As a result, each step of the build had to be explained to the various contractors as they came through.
At times I could tell it was painful for the builders to put their pride aside. After all, they had to learn how to think and build in a new way.
Throughout the build, the acoustician spent a lot of time on-site, observing, guiding, and preventing additional mistakes. Occasionally builders would want to move ahead without clarification, only to find they had to go back and undo or redo something else at their cost.
Most issues dealt with rigid connections between walls that had to remain isolated from each other. Sometimes it was as simple as a few badly placed rivets or support straps that would have completely compromised the effectiveness of the otherwise isolated inner room. I learned that the frequent need to be on-site for quality control purposes is where a lot of the cost comes in when hiring an acoustician.
For me, the most significant benefit of having the acoustician on-site over those many weeks was that it allowed me to ask more questions than one person should be allowed to ask another. Thankfully, he was very generous and patient in sharing his knowledge. The knowledge and information I picked up in those conversations helped build a valuable foundation for my career. I’m excited to be able to share some of that knowledge with you here.
I’ve observed that there are some pretty big gaps in vocabulary and general knowledge about the science of acoustics. In fairness, unless someone has consciously spent time studying and learning about it, this is to be expected.
But because we work in an industry where we are so reliant on applying this science, our general lack of knowledge makes it almost impossible to talk to each other effectively about it. It also makes it very difficult to separate fact from the ever-growing (sometimes unintentional) partial truths and misinformation online.
This brings me to the goal behind this series. My primary objective is to give you a solid start to the constantly ongoing process of creating the most vibration- and transmission-free environment possible, as inexpensively as possible.
Even though the universe seems dead set on allowing things to vibrate, we can mitigate and control how much vibration occurs. In fact, we can even direct where sound waves will travel. This is achieved through decoupling, absorption, adding mass, damping, and painstakingly sealing off air gaps, all of which will prevent flanking.
The majority of low-cost tips I provide in this series involve decoupling and reducing flanking. You can learn more about these processes here.
As I’ll explain in a moment, absolute, full-on “soundproofing” is rarely needed. But if the sound coming in or out of your room is louder than you can work with, the following tip can help:
Take a quick mental inventory of your room. What noises are leaking into and out of it? You may want to make a detailed list of all the things you hear and the time of day they occur. Do you hear any of the following?
- road traffic
- a washing machine in another room
- children in a schoolyard
- incessantly barking dogs
- an air conditioner or furnace
- muffled conversation
Once you’ve identified the offending sounds, arrange them in order from the most noticeable and annoying down to those you can ignore. Finally, mark the sounds you can and can’t control.
This list will help you identify the problem sounds you don’t have any control over. These are the sounds we need to start working on reducing as much as possible. For example, while you may not be able to turn off a neighbor’s washing machine on the other side of the wall, you can turn off yours while working on music.
There is an added benefit to all this. By eliminating the most bothersome or annoying noises, you will probably eliminate many others simultaneously.
Before we get too further into the subject, it might be worth discussing spaces that are probably as close as any to being truly soundproof: anechoic chambers.
In science and manufacturing, it is often necessary to know how much sound an object creates, reflects, or absorbs. The only way to measure these properties accurately is in anechoic chambers. These specialized rooms are so quiet that all you can hear is the device being tested.
Anechoic chambers are built to block out sound from the outside. They use a complex system of acoustic barriers consisting of multiple layers of insulated steel, concrete walls, and bank vault-style doors.
Anechoic chambers are built to reduce vibration down to negligible levels. They also eliminate all internal reflections by using some pretty advanced absorption methods. As a result, these rooms are so quiet you can hear the sound of your heart pumping and the blood flowing around your ear canals.
Companies such as Apple, Microsoft, and even the Air Force spend millions of dollars building anechoic chambers for product testing. Fun fact for you: Microsoft currently holds the record for the world’s quietest room (previously held by Orfield Laboratories, among others).
As remarkable as these rooms are, they are still not completely soundproof. Crank up an external noise source enough, and you will eventually hear it. BUT, they are as soundproof as needed for their application.
Here’s another fun fact: because they eliminate all reflections, anechoic chambers aren’t suitable for recording music. The complex sound reflections of an instrument playing in a room breathe life into recordings when controlled properly. And considering that our ability to know where we are in the world is largely based on aural cues such as reflections, we don’t necessarily want to eliminate them entirely.
One lesson to be learned from anechoic chambers is that absolute silence isn’t necessarily ideal. In fact, you don’t need a completely silent recording space to produce amazing recordings. However, spending less time cleaning up noisy tracks does give you more time to focus on your music and creativity. Remember: your room is unique, so apply the recommendations I make in a way that makes the most sense to your situation.
Points to ponder
This may seem painfully obvious, but in the interest of correcting some misinformation online, I’ll still say it: a room doesn’t HAVE to be “soundproof” to be considered a studio. The only reason to spend time, money, and effort to acoustically isolate your room is if there is something you need to isolate yourself or others from.
What this means is, you DON’T need to isolate your room acoustically if:
- the noise from your room isn’t bothering anybody
- external noise isn’t causing problems when you record
- noise isn’t affecting your ability to hear properly while you edit and mix
To be honest, I often hear my neighbor’s lawnmower from different rooms around the house. But I haven’t spent thousands of dollars trying to isolate myself.
If a noise gets to the point where my life is dramatically affected, I will take steps to isolate myself from it. But if it isn’t bothering me, why would I spend time and money isolating myself?
Applying this thinking to a home studio environment, I prefer to address potentially annoying sounds when they become an issue. If there aren’t any problematic noises, I see no need to spend money on acoustic isolation just to say that I’ve done it.
Of course, there are exceptions to every rule. If you have the opportunity to build a room, it may be worth the added cost and effort to build walls that prevent sound from passing through.
Conversely, if I’m building a room in the middle of a field in Nebraska, I’m not going to worry about isolating myself from anything. In that particular setting, there’s probably nothing to isolate myself from!
Another thing to consider is that you may only have problematic noises at certain times, such as during the day, for example. If you can schedule your recording sessions around these times, you may not have to worry about isolating your room. Instead, spend your money on other necessities such as treating your studio or another microphone or instrument.
That’s it for now. Stay tuned for the next installment in this series: Tips That Won’t Cost You A Cent.
-Alexander E. Jenkins