Soundproof Your Studio

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Over the years of teaching people about soundproofing there is one topic that causes the most fear and that is the dreaded Triple Leaf Effect. However, it is really not something to fear and in this article I will go over what it is, how to avoid it and a couple tricky situations you might encounter during your design and build. 

To understand soundproofing and the triple leaf effect you first must understand how a soundproof system works. The foundation of soundproofing is that you have a barrier like a wall, ceiling or floor and you use a mass spring mass system in that barrier. 

What is the mass spring mass system? It is a physical property that works to block sound more efficiently than just mass. Say you have a solid concrete wall. It is massive and will reflect a lot of sound, but if you were to tap on it with a hammer the sound would fly right through the wall. For this reason we need two walls and an air gap to increase the sound isolation. 

In the prior example if we add another concrete wall with say 8" between the walls then we will have mass (concrete wall 1) spring (the air gap) and mass (concrete wall 2). This creates a much better sound isolation system than just one massive wall. 

Now if we decrease the air gap in half to 4" then the isolation will be worse. Why is that? The spring in this case is air, but it behaves like any normal coiled spring we can see. If you stretch out the spring it is looser and vibrates freely and easily up and down like a slinky. If you compress the spring it becomes rigid almost like a solid object and does not vibrate easily or move up and down. It behaves more like a closed slinky. 

Here is the main and very important point. The looser the spring, aka the bigger the air gap, the more isolation you will get because sound will dissipate from the vibration of the air molecules and convert into heat. The tighter the spring, aka the smaller the air gap, the less isolation you will get because the sound travels through the spring more easily transferring to the other wall. 

Simply put: loose spring good, tight spring bad. Big air gap good, small air gap bad. 

In the above diagram the wall on the left would be more soundproof than the wall on the right because the spring is twice as wide meaning twice as loose, which leads to more transmission loss in the spring. 

So now that we understand the mass spring mass system we can now tackle the triple leaf effect. If we are building a wall with wood and drywall then we can encounter a counter intuitive problem. In the diagram below you can see that the two walls side by side with drywall on both sides of each wall only gets you an STC rating of 40. Wow! that doesn't seem to make sense right? 

Then look at if you remove one layer of interior drywall, you get an STC of 50. If you take those two interior layers and put them on the outside of both walls, you suddenly get an STC of 63. That is a huge jump in soundproofing. 

You now understand why this happens. The spring (air gap) increases when we remove the inner drywall layers, thus increasing our sound isolation. 

The triple leaf effect is when you add a mass layer, in this case drywall, between your double wall system and therefore decrease the air gap making the spring more rigid and less efficient at converting sound waves into heat. 

As a side note, the pink insulation in the wall diagrams increases the isolation as well and works to convert sound to heat through the vibration of the tiny fibrous strands as sound passes through the web of fiberglass or mineral wool. 

Now that you understand the mass spring mass system you have a much greater understanding than most about this triple leaf effect. As long you have an isolation system that gets you to your desired STC or sound isolation needs you can build walls within walls within walls. 

For example, let's say you want to avoid using the exterior walls of your garage because they are very flimsy and have almost no mass. Instead you want to build a new double wall system in your garage and never attach it to the exterior wall. 

As you can see in the diagram above, you have three walls. Many people would call this a triple leaf effect and say it is bad. They would be wrong. The reason is that you still have a double wall system that gets you an STC of 63. If you add more walls around that system it will only increase the isolation. The garage wall doesn't have enough mass, so it is easier and cheaper to build a new wall away from the garage wall. This happens all the time with garage doors. 

You could leave the drywall off of the inside of the garage wall, but it may reduce the mass, which would be bad. If the air gap is already big enough than why reduce mass for the sake of adding more air. You can see that the triple leaf effect is not so simple and that understanding the underlying mechanics of the mass spring mass system gives you much more freedom in your designs. 

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If you walk into any professional studio you will see large studio monitors built into the front wall. This is known as flush mounting and incorrectly termed "soffit mounting" as well. In this article I will go over the pros and some cons to flush mounting your speakers so you can decide what is best for your situation. 

There are numerous benefits to flush mounting your speakers into the front wall. Here is a list of what we will go over in more detail. 

- Eliminate Diffraction At Speakers Edges

- Eliminate SBIR on Front Wall

- Increased Low Frequency Efficiency 

- Improved Stereo Imaging 

The acoustical term diffraction refers to how sound interacts with edges of furniture, partitions and in this context the edges of your loudspeakers. The mid to high frequencies coming from your loudspeaker spreads out the front in 180 degrees. When those waves meet the edges of your loudspeakers they immediately propagate outward in a new direction. As Philip Newell states in his book Recording Studio Design, " 'diffraction' is particularly problematic at the sharp edges of small loudspeaker boxes, where the edges can act like independent sound sources." (Philip Richard Newell, 118)

The term independent sound source is very important because you can almost imagine diffraction as having new little speakers on all of your speaker edges pointing towards your front, and side walls. This leads to more phase issues if not absorbed properly. 

The picture below from coastalwiki.org is a great example of diffraction in water. Sound and water behave very similarly, so this is a good way to visualize the sound waves bending around your speakers. 

Photo Credit: Google Earth and coastalwiki.org.

This is all to say that if you flush mount your speakers in a rigid and dense wall then diffraction will no longer be an issue in your room. 

SBIR or Speaker Boundary Interference Response is an acoustical term that refers to the soundwaves hitting a surface in a room and reflecting back to the listener. The reflective sound waves arrive after the direct sound waves creating phase problems in the room. 

The biggest issue with SBIR with loudspeakers is the low frequency radiation off the front wall and back to the listening spot. This causes dips and peaks in the frequency response of the loudspeaker which can lead to hearing too much or too little bass in your mixes. This then leads to over or under compensating in the mix or master leading to bass heavy or bass light mixes. All of this is undesirable in a control room.

Flush mounting your speakers in a heavy dense front wall means the bass frequencies are only radiated forward into the room. This means you will hear the direct sound of the bass without reflections (assuming the rest of your room is heavily absorbent at low frequencies) and make accurate decisions when recording, mixing and mastering in your room. This then leads to mixes that translate everywhere and speeds up every part of the production process. 

When you flush mount your speakers you are essentially extending the front baffle of the speakers from the left to the right wall. This leads to an increased efficiency in the monitor system leading to as Newell points out, "greater low-frequency efficiency of between 3 and 6dB compared to the same loudspeakers free-standing." (Philip Richard Newell, 381)

This means that the less electrical power is needed, which leads to less heat in the voice coils, "which tends to both reduce power-compression and distortion, and improves the transient response of the system at high SPLs. (Philip Richard Newell, 381)

Although, this is a very technical benefit, it nonetheless is important to mention since better efficiency of the system leads directly to a more accurate monitoring environment. 

Newell finally states that flush mounting your speakers in very heavy rigid boxes inside a heavy rigid wall will reduce any speaker movement due to high SPLs of low frequencies. I will be honest, I can't imagine this happens on smaller home studio monitors, but I could be wrong. Nonetheless, it is another benefit to flush mounting your speakers. 

Not everyone should jump right into flush mounting your speakers. Below is a list of reasons not to flush mount your speakers. 

- You have low quality near field monitors

- You have not addressed low frequency absorption in your room

- You don't know how to properly flush mount your speakers

- You plan to move soon and want to take your studio with you

Not all monitor speakers are built the same and many entry level monitors in the 300-1,000 dollar range probably should not be flush mounted. First, near field or close field monitors are built to be placed on a desk or speaker stands close to your listening position. They are not designed to be flush mounted in a wall. Second, because these speakers are entry level they do not have the fidelity and accuracy that higher quality monitors have. This means they are great for getting started, but are not worth keeping once you are ready to upgrade. If you are thinking of flush mounting your speakers you should also be producing, mixing and mastering at a high level or at least have the budget for high level speakers and room acoustics. 

I would recommend using mid field or far field monitors for flush mounting and making sure they are the best you can afford. Three way speakers that go down to 20-40 Hz are a must and they should have little distortion and a flat frequency response. You should also love your monitors because once they are in a wall you cannot easily swap them out. 

Before you flush mount your speakers you must also have a plan for properly treating the rest of the room. You need to have absorptive walls and ceilings that goes down as low as possible. This means building custom diaphragmatic acoustic walls or using thick insulation panels with big air spaces behind them. It also means treating all surfaces of the room especially corners. 

If you are still working on getting your room acoustics right then flush mounting should wait too. 

If you search "flush mounting monitors" on the internet you will get a lot of answers. I have read almost all of Philip Newell's books, but he does not give his secret away on how to flush mount speakers. This means there is an element of DIY when it comes to wall mounted speakers. Be prepared to do research and design a plan before you jump into flush mounting. You can always hire a studio designer as well. 

The beauty of home studio design is that much if not all of the room acoustics can be moved from room to room. Acoustic panels, free standing speakers and free standing bass traps all mean you can load them up when you move. If you flush mount speakers you will leave a big gaping hole in your wall when you leave. The next owner will have to have your same speakers or tear down the wall. This might be the biggest reason not to flush mount your speakers. So many of us want pro results, but we are in home environments. We can get great results with basic home acoustic principles and a lot of times that is where you should stay. 

I will be honest, I am really interested in flush mounting my speakers and building a Philip Newell style control room. In fact, my next home studio will be just that. However, like many of you I am stuck in where my knowledge was when I built my first studio. I could try flush mounting my speakers, but I wonder is it worth the cost, how long will I own this house and what would the resale value be. On a deeper level I think all of us are constantly torn between wanting better results in our home studios and reality of home studio limits. 

If you are building a professional studio that needs to compete with the best studios in the world, yes definitely flush mount your speakers. If you have great monitors and a great room and want to take it to the next level, yes flush mount your speakers. If you are curious and just want to see what happens, yes flush mount. 

But, if you see the cons as outweighing the pros then maybe wait and keep working on tweaking your listening position, tweaking your room acoustics and saving up for better monitors that you will never have to sell. 

“File:WaveDiffraction.jpg - Coastal Wiki.” Www.coastalwiki.org, www.coastalwiki.org/wiki/File:WaveDiffraction.jpg. Accessed 15 Mar. 2024.

Philip Richard Newell. Recording Studio Design. New York ; London, Routledge, Taylor & Francis Group, 2017.

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Home recording studios are notoriously small in acoustic terms. These small rooms tend to have big problems with the low frequencies and not enough space for proper diffusion. 

In this article I will explore why we need to be careful when adding diffusion to our home recording studios. 

Before we can jump into the discussion of diffusion we first need to define what a small room is in acoustic terms. Acoustic terms means how sound experiences the room not us. Sound needs much more space to "feel comfortable" in a room and sound pleasant to our ears. This is why professional studio tend to be very large in comparison to home studios. 

A small studio defined by F. Alton Everest and Ken C. Pohlmann in "The Master Handbook of Acoustics" states that a small room is 1,000 cubic feet, a medium room is 3,400 cubic feet and a large studio would be 8,000 cubic feet (28.3m3, 96.3m3 and 226.5m3)

A small home recording studio in this example would have an 8 ft ceiling height (2.43m) a width of 10 ft (3m) and a length of 12.32 ft (3.7m). This size is very typical of a home recording studio. 

In professional studios there is always a live room and a control room. It is very difficult if not impossible to blend the two perfectly. However, I am a fan of recording in one room and more and more music is made this way. So, the first question you should ask yourself is how you want to use your room. If it is a live room than diffusion could be useful. If it is a mixing room then you probably want to address the low modal frequency problems with absorption before adding diffusion. 

If you are recording and mixing in your room than you have to decide if you value a live room sound for recording or a flatter response for mixing and mastering. I personally love an accurate stereo image and a tight sounding drum kit and acoustic instruments. For this reason, I would lean towards making my room ideal for mixing and the recordings would also sound tight and even. 

However, if you like a huge drum sound or a big piano sound you may want to give the instrument lots of space. A small room will sound small, but diffusion can make the room sound bigger than it really is. 

  A) Distance From the Diffuser

The main issue with diffusion and specifically quadratic phase grating diffusers is that they need space to fully form a diffuse field. The other problem is that to diffuse at low frequencies the diffusers also need to be very deep, which takes up floor space into your already small room. 

Now how much space do you need. Great question and I have heard a few different answers. Some online forums such as the Arqen step diffuser website say that you should use the 3x rule. This means that your listening or recording spot should be three times the distance of the lowest wavelength diffused. 

If your diffuser goes down to 300 Hz then the wavelength for 300 Hz is 1,130 (speed of sound) / 300 = 3.77ft. Three times 3.77ft = 11.3ft from your diffuser. In a room that has a 12 foot length that would be impossible. 

Well, why do you have to sit so far away? Another great question. Quadratic diffusers and prime root diffusers all scatter energy evenly back in the room, but it takes distance for the scattering to fully diffuse. Before that ideal distance the diffusion will sound out of phase and you will get a comb filtering effect. All that means is what you hear will not be what the sound really is coming from your speakers or instrument. You wouldn't want to listen near in a space that has comb filtering. You may want to record there if you think it sounds good, but it won't sound accurate to the instrument being recording just different. 

What about polycylindrical diffusers? These diffusers can work differently from phase grating diffusers like a QRD or Prime Root diffuser. A polycylindrical diffuser will simply scatter energy back in an indirect form so there should not be phase issues. These could be a better option in smaller rooms, however they take up space and would need to be filled with insulation to increase low end absorption. 

  B) Low Frequency Modal Issues

Smaller rooms suffer from serious low frequency modal issues. This means that the low end from 20Hz - 100 Hz will not sound accurate when listening to your speakers or when recording low frequency instruments like bass, drums, and even voice. 

To remedy this issue you need to absorb as much low frequency energy as possible. In a small room that is not soundproof a lot of the low frequency energy may travel through the walls, which is a good thing for your room acoustic, but could be bad for your neighbors or roommates. If you have soundproofing then the low frequencies will be trapped and bounce around your room, worsening the low end problems. 

All this is to say that in small room you probably should cover all your walls and ceiling with absorption that is at least 5" thick. A common theme in home studio design is to put diffusion on the back wall. However, the back wall is where some of the worst low frequency issues occur. So if you diffuse down to 300 Hz on the back wall then all the low end reflects right back to your listening spot. Instead I recommend using absorption on the back wall to at least absorb down to 125 Hz. Bass traps in the corners and the upper corners where your wall and ceiling meet will also help absorb the low end in your small room. 

To support my argument here is a quote from Philip Newell, one of the most respected and great thinkers on studio design: "In small rooms absorption is the only solution, for whilst diffusion may in some circumstances maintain the stereo imaging over a large 'sweet area,' it nonetheless returns considerable energy to the listening position, and this will colour the sound (Newell, 390). 

  C) LEDE Myth

You may have heard of a control room design called the Live End Dead End or LEDE for short. This design says that a control room should have a fully absorptive front end and an entirely diffuse back wall. The problem with this philosophy is that for the back wall to work as intended you need to diffuse well into the low frequency range. This requires very deep quadratic diffusers to properly diffuse down to 20-100Hz and even then it is difficult. Small room simply cannot give up enough space for proper low end diffusion. 

Small rooms are challenging in many ways and acoustics may be the top issue. My recommendation for home recording studios in the 1,000 - 2,500 cubic foot range is to focus on absorption. Diffusion could be fun to experiment with on the back wall, but they are hard to build and expensive and you may waste money or get sub par acoustics in the end. However, I am not one to discourage experimenting, because at the end of the day it is your studio. 

A good point to remember too is that a flat listening monitoring experience is not what you may want. If you do not plan to mix or master your work, diffusion may add life and a joy to the listening experience. In fact listening rooms often use diffusion for this purpose. 

However, if you want an accurate response when listening back then diffusion may not be the way to go. 

Works Cited:

“DIY Sound Diffusers FAQ.” Arqen.com, 14 Dec. 2013, arqen.com/sound-diffusers/faq/#:~:text=This%20corresponds%20to%20a%20safe. Accessed 6 Mar. 2024.

Everest, Frederick A., and Ken C. Pohlmann. “Acoustics of Small Recording Studios.” Master Handbook of Acoustics, McGraw-Hill, New York, 2015.

Philip Richard Newell. Recording Studio Design. New York ; London, Routledge, Taylor & Francis Group, 2017.

FREE Soundproofing Workshop: https://www.soundproofyourstudio.com/workshop

This is a great podcast for those looking to install soundproof door seals. You will see what I did right...and what I did wrong and get my final take on what door seals I recommend for your soundproof doors. 

FREE Soundproofing Workshop: https://www.soundproofyourstudio.com/workshop

This is a question someone in our community asked me on youtube. Well, I made a video to answer that exact question. 

In this video I will go over: 

In conclusion you will find out if my studio soundproofs drums and what I would do to increase that isolation in the future. 

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This is part two of my series on Philip Newell's control room design. In this podcast I will go over the acoustic interior system. We will cover: 

- How much space room acoustics use up

- Ceiling Isolation System

- The Acoustic Ceiling System

- The Ceiling Wave Guide Panels

- Back Wall Acoustics 

- Side Wall Acoustics

- Front Wall Acoustics 

-Room Liveliness Vs. Anechoic 

- Final Thoughts on how this is all relevant to your own home studio design and build. 

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It's time for another reaction video, this time I am reacting to one of Acoustic Fields video's on the "half truth" of the double wall system. 

In this video I go over: 

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We can't all build professional control rooms, but we can learn a thing or two from how they are built and hopefully apply it to our own control room design. This will be a multi-part series in which I go through a control room design by world renowned studio designer, Philip Newell. 

Professionals would never build a studio in an unsuitable location for recording. In this design the building was already inside a concrete shell. The concrete floor ceiling and block masonry walls were an excellent starting point for a high level studio.

The space was also massive. The control room had 7m x 7m of floor space to work with and 8m of height! That is roughly 23' x 23' and 26' tall ceilings. That is unheard of in the home studio word. Ironically, over 50% of that space would be used for isolation and acoustic control of the room. 

The first step in designing the professional control room is to design the isolation walls. Newel used a concrete block or cinder block filled with sand for his interior isolation wall. In his design he angled the walls slightly, but he states in his book, Recording Studio Design, that both angled isolation walls and room ratios are not of much importance because they will not greatly fix low frequency modal issues. However, angled walls in the acoustic wall can be helpful for the reduction of flutter echo. 

The isolation walls are built with a 5cm-10cm gap from the exterior walls of the building. That is roughly 2-4" of space between the walls. I don't think he added insulation between the walls, but this would help with some added isolation, however the extra cost and labor would probably not add a noticeable difference in the isolation of this structure. 

Lastly, the isolation walls for this design were 4.5 meters tall or roughly 14.7 feet. Remember, when the studio is finished much of that height will be lost to acoustic control. 

Because this mix room is not the main floor of the building and it will share a foundational floor with a tracking room, Newell is using a floated concrete slab. For home studio, I usually urge people not to float floors due to cost and expertise, but again this is a professional studio with millions of dollars in investment and profits at stake. 

The first layer of the floor is a 10cm 70kg/m3 (4" 4lb/ft3) layer of mineral wool. This is the spring that will isolate the concrete slab. You can use isolation springs, but they are more costly and difficult to use. I believe Newell felt the isolation would be adequate for this design. He also states that this method could lead to better isolation because of the damping of the structural floor beneath the mineral wool. 

After the mineral wool you need to add a layer of plastic to prevent the concrete from soaking into the mineral wool. After that he added two layers of overlapping OSB took prevent the mineral wool from getting trampled by the workers laying the slab. 

Lastly, they poured a 10cm concrete slab (4") over top of the OSB sheathing. 

To keep the concrete from touching the isolation walls they added a vertical layer of mineral wool between the isolation floor and the isolation walls. This ensures that concrete never reaches and connects the interior walls with the interior floor. 

Now the exterior ceiling of this room is at 8m and is a concrete ceiling. The second wall to complete the isolation shell is made of huge reinforced wood beams. The beams are made of two 20cmx5cm (2x8) boards glued and nailed together. Then a 10cm x 5cm (2x4) added on the top and bottom and finally two 25mm (1/2") plywood sheets glued and nailed to each side. See the diagram below. 

I put these beams at 16" OC, but for construction of this nature it would be wise to have a structural engineer on your team to verify loads and make sure you are not over sizing or undersizing your beams. 

Below is another image of the finished beams attached to the inner isolation wall. You may be wondering if this short circuits isolation. I wondered the same thing. My thinking is that Newell knows the acoustic shell will be also helping with isolation and the need to decoupe the ceiling a second time is probably not necessary. Plus, the isolation cap, as he calls it, is far below the true ceiling of the room. This will also help with isolation. 

Now I am not going over how the isolation ceiling is finished, because that will happen last after the acoustic shell ceiling is finished. We will go over this next week in part 2 of this series. 

Home studio soundproofing and pro studio soundproofing may look very different. If someone gave me a big enough budget I would use Newell's design, but for most of us mere mortals we must use the best materials we can within our budgets and space constraints. 

This said, using concrete sand filled blocks and choosing a suitable location for your control room will always put you in some of the top designed studio in the world, at least in terms of what you are starting with. 

My hope is that this helps you learn more about how the pros design studios so you can glean some wisdom from this approach. 

Works Cited - 

Philip Richard Newell. Recording Studio Design. New York ; London, Routledge, Taylor & Francis Group, 2017.

By The Book (affiliate link): https://amzn.to/4b7zyxd

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One of the least sexy topics in soundproofing is fire stopping. Okay there may be no sexy topic in soundproofing, but this one is not fun, but important. In this article you will learn what firestopping is, why we need it and how to incorporate it into your soundproof wall system. 

Fire stopping is a construction technique where you use a fire retardant barrier to block a cavity so fire cannot spread through that cavity. In soundproofing this is important in our double wall and double ceiling cavities. 

In normal wall framing our walls have bays with insulation. If a fire were to break out inside of one of the bays it would not be able to spread easily to the next bay or to your ceiling. See the diagram below. 

Notice how fire cannot escape the through the bottom, sides or top of a typical stud wall. However, with a double stud wall there is essentially a chimney in between your two walls. See below: 

This gap at the top means a fire could easily spread to your ceiling and throughout the inside of your wall system without you even knowing. For fire safety it is important to seal that opening at the top of the wall, but how do you do that without bridging your two walls and negating all the benefits of a double wall system? 

I learned this fire stop technique from Rod Gervais in his book, Home Recording Studio: Build It Like the Pros. He says to use compressed rockwool or any rigid insulation batt to decouple the fire stop from the inside wall. See the diagram below: 

Here is a side view section of a design I am working on for a client. Notice the rigid batt insulation sitting on top of the top plate. This insulation could be 3lb/ft3 of Rockwool, Thermafiber or any similar brand. In this diagram it is 2" thick and is compressed 50% to 1". This compression is what keep the isolation intact. We don't want to compress the batt 100 percent because then the drywall would touch both walls. 

On top of the insulation batt is 1/2" drywall that is cut to span the gap between the two walls. It should be screwed in to the inner wall top plate on top of the insulation with as few screws as possible or you could use contact adhesive to minimize the connection points. Then you should seal between the rockwool and 1/2" drywall with fire caulk to create an airtight seal.  

Below is another diagram with a perspective view of the fire stop around two walls. 

Notice how the firestop seals the gap around the entire room making it much more difficult for fire to spread up into the ceiling. 

Although this adds extra cost and labor to a build it is, nonetheless, an important part of the double wall design. It is always good to keep fire safety in mind when we are building a typical structures for sound isolation. 

Work Cited

Gervais, Rod. Home Recording Studio: Build It Like The Pros. 2nd Edition, Course Technology Cengage Learning, 2011.

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Are you going crazy trying to find a way to absorb low frequencies in your recording studio? Look no further. Finally there is a way to absorb low frequencies using a broadband absorber. Let's dive in! 

If you haven't heard or read any of Philip Newell's books, I suggest you do. He has been building and designing studios for decades and has worked with some of the biggest names (The Rolling Stones). In his book Recording Studio Design 4th Edition he describes a panel wall absorber system that can absorb down to 30Hz. Let's go over the design. 

This is my rendition of Philip Newell's design. He of course does everything in metric and uses cotton waste felt instead of my recommendation of Knauf ECOSE insulation batts. I would love to use cotton waste felt, but I couldn't find any good suppliers in the United States that were cost effective. 

This said, let's dive into the design. A very important part of this acoustic wall is that it is built at least 2" from the isolation wall. 4" is better and one to three feet is even better than that. However, as Newell states in his book many studio owners do not see the benefit of better acoustics at the cost of floor space. For us home studio nuts we also need to find a balance between space, budget and our desire for pro level acoustics. I believe we can find that perfect balance and this design gets us closer to the truth we are seeking. 

After the 2-4" air space we then have a 1" 3lb/ft3 Panel of Knauf ECOSE insulation. You can buy them in 2" panels and then cut them right down the middle for this design. Then Newell says to use a 5kg/m2 deadsheet (1lb/ft2). Now a deadsheet is really another name for a limp membrane having considerable inertia and little stiffness. In the United States we can use Mass Loaded Vinyl (MLV). Then we have another layer of Knauf Insulation. Then a 1/2" thick piece of drywall sandwiched over another layer of MLV and another 1/2" piece of drywall. 

Finally, we reach the stud wall frame. Fill this with R13 Owens Corning unfaced insulation. Then seal the frame wall with a layer of 1 lb MLV and one last layer of 1" Knauf Ecose Insulation. Wow, that was a lot. You might be wondering why we need all these layers. 

Yes, it is more of an acoustic wall although you could build a panel out of this design if you wanted to save money. The key to this system working is the multiple materials working together to stop soundwaves through absorption and damping at different frequencies. Let's take a trip through the wall as a soundwave. Yay!!! 

So we start off hitting the Knauf Insulation. This will absorb our mid to high frequencies from say 500-20K Hz. Then we will fly through a deadsheet and this will dissipate some of the mid and low frequencies through damping. Then we will fly through our Owens Corning Insulation and even more of the soundwave will dissipate as heat. Then the low frequencies that remain will hit the drywall - deadsheet - drywall and get absorbed in the pressure cavity of the mass spring mass system we created with the sealed framed wall. Lastly, any remaining sound would hit the insulation - deadsheet - insulation and lose even more energy. Finally, the sound will hit our isolation wall. Depending on the type of wall (drywall vs mortar) the energy may get absorbed again or reflected back and sent right back through the whole system again. 

Needless to say, the low end frequencies really do get trapped in this system. Hence, it's ability to absorb down to 30Hz. In an ideal studio room you would line all four walls with this system. In a control room or a mix/production studio as is so common today you should use this system on three of the four walls and leave one wall and the floor reflective to keep the live of the room intact. 

Great question! The total wall costs $8.65/sqft if you use the materials I mentioned above. That does not include the cost of the wood frame. To acoustically treat a room that is 15ftx20ft you would be looking at around $2,500 in materials. Yes, that is a lot of money, but honestly insulation panels that only absorb down to 125hz would cost you that much as well if you bought professional ones. We also did not look into the ceiling, that will come in another article, but that will add another 1,000-2,000 as well. However, if you have looked at Acoustic Fields then you know getting this type of acoustic paneling can cost 20-40 thousand dollars, so why not use basic construction materials and get the same if not better results. 

Don't trust me, trust Philip Newell. He is the one who has taught me all these great studio design philosophies. Again, if you are serious about studio design I encourage you to pick up his Recording Studio Design book. 

Work Cited: 

Philip Richard Newell. Recording Studio Design. New York ; London, Routledge, Taylor & Francis Group, 2017.