Acoustic treatment is one of the most essential parts of your music studio; it allows you to trust your ears. An untreated room will color the sound produced by your speakers in various ways, which means the mixing and mastering decisions you make may be misinformed. The result is that the mixes you perceive as balanced on your speakers won’t translate well to other playback systems. I’ll be showing you how to sound treat your home studio effectively.
I’m sure that someone, at some point, has told you that mixing on headphones is worse than mixing with studio monitors. What no one seems to mention is that this only holds true if your speakers have been placed in an acoustically treated studio that’s been optimized to achieve a near-flat response listening environment. In an untreated studio, you’re almost guaranteed to produce better mixes with your headphones because the problematic room is scratched out of the equation.
Most producers know that untreated rooms “aren’t ideal for mixing,” but I think saying that untreated rooms “will catastrophically fuck your shit up” is a slightly more accurate statement. For example, common acoustic problems can lead to perceiving multiple 12+ dB resonance boosts in the low-end of your mix, hearing echoes, and perceiving notched filtering effects throughout the frequency spectrum of your song. Mixing in an untreated studio is like driving with a blindfold on.
This guide is split into 6 sections. We’ll start by taking a look at the acoustic problems your room presents, and then move on to different types of acoustic treatment and areas of your studio that will substantially benefit from acoustic treatment. I'll show you how you can optimize your studio’s acoustic’s using room calibration software before debunking some classic acoustic treatment myths. Finally, we'll take a look at how you can build your own professional quality acoustic panels for just $25/panel.
- Common Acoustic Problems
- Types of Acoustic Treatment
- Critical Treatment Zones
- Optimizing Your Studio’s Acoustics
- Acoustic Treatment Myths
- How to Build Your Own Acoustic Panels
1. Common Acoustic Problems
There are some common acoustic problems that you’re going to face regardless of the room that you’re in. These issues include comb filtering, flutter echo, room modes, and excessive decay time.
Mixing music in an enclosed space provides many challenges because of the way sound interacts with the room that you’re in. Unfortunately, working in an open field is not practical, which means it’s better to attempt to work in, and control, the acoustics of an enclosed space.
I’ll be providing the following acoustic problems with some more context throughout this guide, so if they feel a bit arbitrary as you’re reading about them, just hang tight.
When a direct sound is combined with its reflection, something known as a comb filter is created. It’s characterized by the notches introduced to the frequency response of the resulting sound. The location of the notches within the frequency spectrum is dependent upon the delay time between the direct sound and the reflected sound. Comb filtering is the effect flangers introduce to an audio signal, and it’s not something you want your listening environment imparting on your perception of a mix.
The following video demonstrates how reflections created by a white board interact with the direct sound coming from a speaker to create a comb filtering effect at the position of a microphone.
An acoustic problem known as flutter echo may occur when a sound reflects back and forth between untreated parallel walls. If the time between reflections is large enough, your ears will perceive these reflections as an echo, rather than sound that's diffusing throughout the room. This effect is strengthened by the regularity of the echoes, making it potentially quite audible to the human ear. The echo will eventually fade away due to the natural absorptive properties of the walls, but flutter echo can be detrimental to the effectiveness of a critical listening environment.
The following video demonstrates a 7 second flutter echo created by hard parallel walls in a large hall. This effect may not play out to the same degree in your studio, but it's important to know how flutter echo manifests itself.
Room Modes, Standing Waves, Nodes and Anti-Nodes
The sound-pressure level in a room will be different at various positions and vary based on frequency. This is due to the way the sound produced by your speakers is reflected off of boundary surfaces like walls, floors, your ceiling, and even your desk. The issue that arises is that certain spots in your room will potentially be more resonant within specific frequency ranges than others; these resonances are referred to as room modes.
Room modes, standing waves, nodes, and anti-nodes are the main culprits responsible for why you have trouble setting the level of your low-end properly. If you’ve set up your mixing position at a standing wave’s node, you’ll hear a lack of bass, and if you’ve set up your mixing position at a standing wave’s anti-node, you’ll hear an abundance of bass. In either situation, the level adjustments you make to compensate for your perception of the low-end will cause your mix to suffer when played back through a different speaker system. Read “The Reason You Always Mix Your Bass Too Quiet/Loud” for an in-depth look at room modes, standing waves, nodes, and anti-nodes (with pictures and animations).
Imagine what it sounds like when you yell in a gymnasium; the sound is “lively.” There’s a clearly audible “tail” to the sound that slowly decays over time. Now imagine yelling in your car with the windows rolled up; the sound has a much more “dead” characteristic to it, and the decay time probably isn’t very long.
Striking a balance between a “live” room and a “dead” room is important and also subjective. A “live” room will allow the sound produced by your speakers to interact with it to some extent before it decays, while a “dead” room will absorb the sound almost instantly.
A room that is too lively can interfere with your perception of the sound produced by your speakers; it does this by highlighting a number of the issues already mentioned, whereas an entirely dead room can sound unnatural. It’s ok for sound to interact with your room to some degree, but it’s essential to control how these interactions occur. Acoustic treatment is all about managing chaos.
2. Types of Acoustic Treatment
Before moving ahead with acoustic treatment, I recommend that you optimize the listening position of your room. This will allow you to minimize acoustic problems, making the application of acoustic treatment easier, cheaper, and more effective. The primary forms of acoustic treatment I’ll be covering include absorption, reflection, as well as decoupling and isolation.
Energy can neither be created nor destroyed, but it can be changed from one form to another. Absorbers convert sound, which is the vibratory energy of sound particles, into heat. There’s no need to worry about sound burning your studio to the ground because the amount of heat that absorbers generate is insignificant.
When a sound wave comes in contact with an absorptive material, its energy is reduced. In practice, some of this energy will likely continue propagating throughout your room, but you can think of absorbers like stop signs that tell sound to slam on the brakes. Dense, porous materials work exceptionally well as absorbers; sound enters through the pores, gets trapped inside, and is then converted into heat.
Common types of absorbers include porous absorbers, panel absorbers, and volume or resonance absorbers. Porous absorbers do an excellent job of absorbing high frequencies, whereas panel and volume absorbers are more suited for low frequencies.
When a sound comes in contact with a reflective material, its energy is redirected. In practice, some of this energy will likely be absorbed by the material the sound wave comes in contact with, but most of the energy will be focused into a new direction. Hard, organic materials like wood do a great job of reflecting sound. Reflectors also tend to be unique in their shape, often with jagged designs meant to diffuse the energy of sound waves throughout rooms.
Sound reflections do a lot to help us, as humans, make sense of the space around us. We can’t see with our ears in the same way that bats can, but we are able to make sense of our surroundings to some extent. If you close your eyes and clap your hands, the sound of the clap interacting with the room you're in will give you a sense of the room’s size, shape, and potentially even the material the walls are made of.
If you’re trying to minimize the impact a room has on the music you’re producing, why not just scrap the reflectors/diffusors, and grab a ton of absorbers? Rooms like this exist, and they’re called anechoic chambers, but they’re expensive to build, and you can begin hallucinating if you stay in them for too long.
It’s ok for your room to sound like a room, but you should do your best to deal with issues that are going to cause you to make poor mixing and mastering decisions. By adding too many absorbers, you may deaden your room to the point where it sounds unnatural. One workaround for this is to use reflectors/diffusors in place of some absorbers to keep the room sounding lively, while simultaneously dispersing sound throughout the room to avoid issues like flutter echo and standing waves.
Decoupling & Coupling
The sound waves your speakers produce are the result of a membrane vibrating back and forth. A speaker’s enclosure can actually cause playback inaccuracies if it vibrates in addition to the vibrating membrane. Two common ways of preventing enclosure vibration include decoupling or coupling your speakers with the floor of your studio.
Decoupling involves reducing the amplitude of vibrations that pass from your floor to your speakers (and vice versa) by making use of either damping pads or damping feet. These damping devices work like absorbers in the sense that their purpose is to convert the energy of vibrations into heat. If your floor is made of wood, and it's responsive to footsteps or the rolling around of your studio chair, decoupling your speakers from your speaker stands, and your speaker stands from your floor, can help prevent jostling the enclosure of your speakers.
Coupling attempts to join your speakers with your floor using speaker spikes. You’ll only want to use coupling for dense floors made of materials like concrete that have a large mass. The large mass of the floor is what will allow you to dissipate vibrations from your speaker enclosure effectively.
3. Critical Treatment Zones
When your speakers produce sound, there are three distinct stages in which you perceive it. First, you hear the direct sound coming straight from your speakers, then you hear the early reflections that have bounced off boundaries like your desk, walls, floor, and ceiling. Finally, you hear the sound’s reverberant field, which is a complex network of reflections created via the original sound interacting heavily with your room.
The four most problematic areas in your studio include the ceiling above your desk and the walls to the left and right of it, the corners of your room, the parallel walls to the rear of your room, and the back wall of your studio. Applying appropriate acoustic treatment to these critical positions can significantly reduce acoustic problems.
I'll be referencing products from GIK Acoustics for those of you looking for store bought acoustic treatment solutions. This post isn't sponsored by them; they just happen to have a comprehensive range of acoustic treatment products.
The direct sound from your speakers will arrive at your ears before any of the room’s reflections. This initial wavefront is the most unhindered version of your mix. It's in your best interest to create a clear separation between the direct sound generated by your speakers, and the early reflections created by your room.
Early reflections arrive at your ears soon after the direct sound, with the first early reflections bouncing off the walls to the side of your desk, as well as the ceiling above it. Early reflections can end up reflecting off the back wall of your studio too. Depending on the orientation of your desk and speakers, you can also experience early reflections bouncing off the flat surface of your desk.
When a sound is produced within a space, it's possible to measure the impulse response that's generated. A room's impulse response consists of a few different components. There's the pre-delay, which is the time between when your speakers produce sound, and when the direct sound reaches your ears. There are the early reflections that arrive slightly after the direct sound, and then there's the reverberation network that forms after the early reflections. We'll take a look at the software capable of measuring impulse responses a little later on.
You want to apply acoustic treatment to your room in a way that creates a clear distinction between the direct sound and early reflections. This will help reduce comb filtering. A popular method of dealing with early reflections is through the use of absorbers.
You can use a mirror to find the early reflection point along a side wall by sitting in your listening position, and having a friend slide the mirror along the wall until the acoustic axis of your speaker is in view; this is the spot where you’ll hang an absorption panel. The 242 Acoustic Panel works well for treating early reflections.
To deal with early reflections from your ceiling, you can suspend a large absorption panel halfway between your listening position and the speakers. Mounting bracket kits that are used to suspend acoustic panels are pretty cheap, and installing these ceiling panels, or ceiling clouds, is a rather simple undertaking.
Room modes end up in corners, so this is where bass builds up. Placing bass traps in the corners of your room helps to convert this low-end energy into heat.
Bass traps come in either the form or panels or wedges that butt up into the corners of your room. A common place to install bass traps is where your walls meet one another, but some people also choose to apply bass traps where the walls meet the ceiling, and/or where the walls meet the floor.
The acoustic treatment in the following 3D image is what I consider to be the minimum number of bass traps that you should apply to your studio. Foam wedges from Amazon don't work well as bass traps because they aren't dense enough to absorb low frequencies. For a better solution, check out Tri-Trap Bass Traps.
Exposed parallel walls, like the rear sidewalls in your studio, are something that you want to avoid because they can cause flutter echo. Installing reflectors/diffusors like the Q7d Diffusor in this critical zone will scatter the sound that hits them, and prevent flutter echo from occurring.
If you find that your studio still sounds too lively with reflectors/diffusors in this position, you can try installing absorbers instead. However, if the absorbers don’t deal with the flutter echo, you may want to take a look at hybrid diffusor/absorber options.
The back wall and the front wall in your studio are also parallel with one another, so flutter echo is a potential issue yet again. On top of this, standing waves are of particular concern. Having moved your desk around, you should have already minimized the effect of standing waves to the best of your ability, but there is acoustic treatment you can apply to the back wall of your studio to further reduce the adverse effects of standing waves.
Your back wall is where you’ll definitely want to make use of thick hybrid acoustic treatment like GIK Acoustics' Monster Bass Traps. Absorption will reduce the energy of bass frequencies, significantly lessening the adverse effects of standing waves, and reflection will help with diffusion, effectively dealing with flutter echo.
Some people choose to apply acoustic treatment directly behind their computer monitor, which is fine, but I would argue that treating your back wall is of a higher priority. By the time sound travels to your back wall, and reflects back to the front of your studio, the damage has already been done; untreated low-end frequencies will have already created standing waves, and your perception of the bass in the music will already be skewed.
4. Optimizing Your Studio’s Acoustics
I don’t want you to think that the acoustic treatment applied to the 3D rendering throughout this guide is the only way to treat a room; it’s not. Everyone’s studio is unique in its size, shape, and materials. I hope that you’ll take the concepts covered in this guide, and use them to make your own room treatment decisions.
Once you’ve applied acoustic treatment to your studio in a way that theoretically makes sense, the next step is to refine your set up using room analysis software. This process can be a little bit time consuming, but Room EQ Wizard (REW) is free software, and the only expense is a room calibration microphone, which sells for anywhere between $49-99, depending on whether you purchase the condenser microphone or USB microphone.
REW looks like an archaic Windows 97’ application, but the data it provides is what is of importance. This software includes tons of different acoustic-focused modules. The two that I find to be of particular importance when applying acoustic treatment are the room simulator, which can help you predict where it’s a good idea to use acoustic treatment and the real-time analyzer (RTA) that will provide you with visual feedback regarding the frequency response of your listening position. REW also allows you to measure impulse responses.
I’m not going to dive too heavily into how to use REW within this guide since there are plenty of resources available online, but data analysis is a critical part of acoustic treatment. Tossing up acoustic panels and hoping for the best isn’t enough. Every studio is different, so what works for one studio may not work for another.
Once you’ve optimized your studio to the best of your ability, you can use software like Sonarworks’ Reference 4 to remove unwanted coloration from your studio speakers. This program uses its own dedicated microphone to analyze the frequency response of your listening position. It applies corrective EQ to your audio output in an attempt to achieve a flat frequency response. Reference 4 can help make up for the deficiencies in your room that you’re having trouble dealing with through the use of acoustic treatment.
If you don’t trust yourself to work through this optimization process yourself, or simply don’t want to, companies like GIK Acoustics offer free acoustical advice. They’re able to recommend certain acoustic treatment products based on the dimensions of your room, along with what you intend to use the room for. For example, they may recommend different setups based on whether you’re planning to use your studio for recording, mixing, or mastering purposes.
5. Acoustic Treatment Myths
The black foam acoustic panels that you can buy bundled on Amazon are painfully ineffective. Using them is better than working in a room with exposed drywall, but they're useless for mid to low-end frequency absorption; this is because they simply aren’t thick or dense enough to provide broadband acoustic treatment. In the same vein, stapling egg cartons to your walls won’t do much to help with room acoustics either.
Hanging moving blankets on your walls is another popular acoustic treatment option, but if you’re going to use them, you need to make sure that you find thick ones with extra padding. Online pictures can be somewhat deceiving, so make sure to take a look at their size, along with their weight. The heavier they are, the better; having said this, moving blankets aren’t going to do much to absorb low-end either. At best, they may help treat your mid-range.
6. How to Build Your Own Acoustic Panels
I understand that everyone is looking for a way to save money, and I’m the exact same way. Building your own acoustic panels isn’t that expensive (around $25 per panel), and the quality of the panels you end up with is extremely high.
Two of the more popular materials for building acoustic panels include Rockwool, which is a non-fiberglass insulation material, and Owens Corning 703, which is a fiberglass insulation material. Buying these materials in bulk from Home Depot will drastically deflate the cost, so consider looking around for some other producers interested in building their own acoustic panels; you can split the cost of insulation with them.
The following acoustic panel build by VO TECH GURU is one of the best acoustic panel tutorials I’ve found online. You can purchase all the supplies you need for this DIY build here.
Investing in acoustic treatment may not be as flashy or fun as getting new plugins, but it has a tremendous impact on the quality of music that you’re able to produce. Mixing and mastering music in an untreated studio is a poor option, and is shattered by the effectiveness of studio headphones; especially in conjunction with the headphone version of Reference 4.
If you can’t create an acoustic environment that allows you to perceive your mix more accurately than the mix produced by your headphones, you’re better off just using headphones. Unfortunately, there’s no middle ground. If you’re going to head down the acoustic treatment path, you need to go in guns blazing and make sure that you follow through with the most essential step of the process; room analysis and optimization.
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