The Ultimate Acoustic Treatment Buyer’s Guide 2021


So you’re wondering which acoustic treatment you should buy. In this comprehensive buyer’s guide, we’ll go through everything worth considering before you make any decisions about any acoustic treatment.

If you’ve found yourself asking, “which acoustic treatment should I buy?” this extensive resource is for you.

Please feel free to jump around this article and read all additional resources I have provided links to.

With that, let’s get into this comprehensive acoustic treatment buyer’s guide to help you in your next acoustic treatment purchase!

Related article: Top 11 Best Acoustic Treatment Brands For Home & Pro Studios


Table Of Contents


What Is Your Acoustic Treatment Budget?

The first thing to consider when making any purchase is your budget. Money can be a touchy subject for some, and so I’ll keep this section brief.

I would never advise anyone to overspend on any audio equipment. Know what you can realistically afford, and do your best to stay within those limitations, whatever they may be.

Acoustic treatments range significantly in price. The market is rather large, and so there should be a good selection for any budget.

Note that some retailers offer payment plans, which could be an option.

Consider the cost to benefit ratio of the purchase of the acoustic treatment. For example, if the treatment is needed for business, perhaps stretching the budget is more appropriate. On the other hand, if you don’t plan on making money with the treatment, perhaps a more conservative budget is appropriate.

Also, consider any additional accessories or upkeep that may be required for your acoustic treatment.

Only you can determine your budget. All I’m here to say is that you should consider it.

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Absorption

Acoustic absorption is the process of sound wave energy being absorbed by a material. Certain materials will be more absorptive than others, and soft materials tend to absorb more sound wave energy than hard materials.

Ceramic tile, concrete, plaster, metal, glass, hard plastic and even wood are more reflective than absorptive. Sound wave energy will bounce off the surfaces, causing echo, reverb and even build-ups of resonant frequencies within the room.

Common absorptive materials include fibreglass, rock wool, and foam. The materials are much less reflective than harder surfaces and act to absorb sound wave energy. These relatively porous materials “absorb” the energy of vibrating air molecules (due to sound waves) and turn it into heat through friction. 

It’s critical to note that, when it comes to absorption, longer wavelength sound waves (lower frequencies) are less absorbable than shorter wavelengths (higher frequencies).

Acoustic panels (and acoustic foam) effectively absorb mid and high-frequency sounds, while bass traps are typically required for bass frequencies. We’ll discuss this further in the section on bass traps.

Note that acoustic panels are generally made of acoustic foam in a proper frame. Acoustic foam and acoustic panels largely produce the same result of absorption. You may come across the term “ceiling cloud,” which is effectively an acoustic panel made specifically for the ceiling.

To reduce flutter echoes and general mid-range muddiness due to reflections and reverberation, acoustic panels are used. These are relatively thin and cover more space with less material. They’re typically made of a frame and a certain thickness of absorptive material.

Acoustic panels are typically placed on the wall, though they can also be used on the ceiling. They’re rarely ever used on the floor, as floor space is typically vital in rooms, and we wouldn’t want to step on these panels either.

In absorbing mid and high frequencies, these panels also reduce resonances in the room.

Note that the thicker the acoustic panel, the more absorption/attenuation will take place. Additionally, thicker panels will absorb deeper frequencies.

Note that thick curtains, carpet, and studio furniture can act to absorb sound energy within a room. However, proper acoustic panels can truly make a difference in the acoustic treatment of a room.

Use absorption with diffusion to achieve the best results in acoustic treatment.

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Diffusion

As the name suggests, diffusion happens when a sound wave hits an uneven surface and is reflected in multiple different directions. This is different than sound reflections at smooth surfaces, where the reflection angle is strictly equal to the incident angle.

By spreading the reflected waves, diffusion keeps standing wave resonances from forming and greatly reduces the flutter echo of the space. The various weaker reflections (as opposed to the stronger single reflections) all interact and largely cancel each other out within the room.

Diffusers can be purchased to achieve this effect, though full bookshelves and other uneven surfaces can also provide diffusion within the room.

Use diffusion with absorption to achieve the best results in acoustic treatment.

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Bass Traps

Bass frequencies can cause severe issues with room resonances (modes), where certain frequencies resonate and are amplified within an acoustic space.

The long wavelengths of bass frequencies are difficult to tame with standard thin absorptive acoustic panels. These long wavelengths are more difficult to attenuate since they move air molecules over longer distances. Thinner panels are less effective at handling these longer wavelengths.

Furthermore, bass frequencies tend to accumulate in the corners of the room. The interference of bass frequency reflections will cause varying bass responses depending on the listening position within the room.

The solution to these bass issues comes in bass traps, which are large absorptive blocks typically placed in the corners of the room. They are thick enough to absorb the long, low frequencies effectively and help clean up the bass of the room and the variety of bass responses throughout the room.

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Control Rooms Vs. Live Rooms

Control rooms are the room where the engineers and producers monitor, mix and master the recorded audio. Live rooms are the rooms where the music, voiceover, etc., is recorded from.

So, how should the acoustic treatment strategy change between these two environments?

Acoustic Treatment In Control Rooms

Control rooms should usually be pretty dead with little to no character. The goal is to monitor the audio in the most accurate way possible, and any room acoustic characteristics will affect the way in which the sound waves are heard.

That being said, a bit of liveliness won’t ruin the monitoring environment.

50-80% coverage is typical in control rooms, with a focus on absorption. Some TV mix rooms and those where jazz and classical music are mixed are a bit more lively with 30-60% coverage and a good amount of diffusion.

After all, the final “consumer” of the audio will likely be listening in an acoustic environment (unless they listen through headphones), so it’s useful to have a room that offers some acoustic reflection. Of course, the less character, the better, and control rooms should practically always be treated more than live rooms.

Acoustic Treatment In Live Rooms

Live rooms vary tremendously in their shape, size, and acoustic treatment. Some of the world’s finest live rooms are designed with a specific acoustic character and require only the most sparing acoustic treatment.

Live rooms can have less than 20% coverage if their natural acoustics are particularly stellar. However, it’s common to see up to 50% coverage with an about-even mix of absorption and diffusion.

In the worst-case scenarios where the live room is resonant and reflective (like in some home studios), a higher coverage percentage could be required to reduce unwanted reflections and resonances.

Acoustic Treatment In Isolation Booths

Isolation and vocal booths benefit from 80% coverage or more since they are designed to be acoustically dead. These rooms are often small, and any flutter echo could ruin the recordings done within. The acoustic treatment in these rooms is focused on absorption rather than diffusion, and bass traps typically aren’t needed.

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Acoustically Treating The Room

Now that we have a solid idea of how acoustic treatment works and the main components of good acoustic treatment, let’s discuss the practicalities.

As discussed, acoustic absorption and diffusion should be used in tandem, though not necessarily in a 50/50 split.

It’s also worth noting that 50% coverage is often sufficient. As was discussed above, unless you’re opting to treat a vocal/isolation booth, 50% can work in nearly all situations. Sometimes more is needed and sometimes less.

In terms of the key areas for acoustic treatment, left untreated, the trihedral corners will cause the most issues, followed by the dihedral corners, and finally, the flat surfaces (namely the walls and ceiling).

As the name suggests, the trihedral corners are where three surfaces come together (two walls and the ceiling or two walls and the floor). I’ll restate that these areas are prime for bass accumulation and are best treated with bass traps.

In fact, if you have a very small budget, I’d recommend treating these trihedral corners with bass traps before anything else.

Next are the dihedral corners (where two surfaces meet). The floor-wall corners are typically left alone, but the wall-wall and wall-ceiling corners can be treated if need be. Larger bass traps can be used to cover these corners.

Alternatively, we can bend acoustic foam to fit neatly in the corner. Leaving a bit of open air between this foam and the corner can also be left to enhance low-end attenuation.

Finally, the flat surfaces are where acoustic panels and diffusers go to handle much of the mid and high frequencies.

When mapping out your room, consider the current setup. Ask yourself if there is any particularly reflective furniture and how many windows are in the space. Next, determine the objects in the room that are already offering absorption and diffusion.

Listen to the room as it is and try to identify any resonances. Walk around the room with music playing and notice if there are any specific locations where the bass drops out or increases in intensity. When the room is silent, clap your hands and listen for flutter echo.

With the rough idea of 50% coverage, plan what bass traps, acoustic panels and diffusers you may need.

Once you have all the components of the acoustic treatment, take your time to measure and plan their placement. Remember the adage, “measure twice, cut once.”

Use proper adhesive and carefully apply the bass traps, acoustic panels and diffuser into place. Enjoy your newly treated room!

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Reflection Filters & Gobos

Reflection filters and gobos are particularly useful for recording, especially if you plan on recording in an untreated room (like in your rented apartment where you can’t mount/glue treatment to the walls).

A reflection filter (sometimes referred to as a vocal shield) is a physical absorptive acoustic treatment barrier that is generally placed just behind a microphone that typically extends around to the sides of the mic. These filters are best positioned at the same height as the mic.

We can capture a more direct signal by providing an absorptive barrier just behind the microphone and singing/speaking or otherwise directing sound toward the microphone. The sound waves that would pass by the microphone, reflect off of surfaces and return to the microphone capsule are instead absorbed by the reflection filter.

Gobos are essentially portable freestanding acoustic panels. These acoustic barriers are typically used in live rooms to achieve more separation between musicians and their microphones. These gobos have the benefit of improved acoustic isolation without the burden of having different musicians in different rooms or relying on overdubbing. They allow the performance to happen all at once while improving isolation.

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A Note On Soundproofing

Soundproofing is closely related to acoustic treatment in that it will effectively change how sound reacts in and around a room’s environment.

While acoustic treatment is great for reducing echo, reverb, resonance, and overall muddiness in the listening environment, it’s insufficient in soundproofing spaces.

Soundproofing is the process of blocking sounds from entering or escaping an acoustic environment rather than affecting the acoustics within the environment.

Good soundproofing is dependent on two main factors: the density of the room’s outer boundaries (walls, floor and ceiling/roof) and the gaps between the layers of such boundaries.

The denser the material in the walls, floor and ceiling/roof, the less sound will travel through. Note the distinction of density rather than thickness. For example, a thick wall made mostly of insulation will provide less soundproofing than a thick wall made entirely of concrete.

That being said, air gaps between the exterior surfaces of a room also play a role. This is especially true if the gap eliminates any physical connection and resonance between the layers. This factor has made “floating room” isolation booths rather common in home and commercial studios.

These floating rooms are designed to fit within a room without touching the room’s boundaries and to be placed on isolation pads that mechanically isolate the booth from the floor of the outer room, thereby reducing mechanical noise transfer.

So thicker walls and double walls (along with floors and ceilings) will influence soundproofing more than any acoustic panels, diffusers, or bass traps ever could.

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This article has been approved in accordance with the My New Microphone Editorial Policy.

Arthur

Arthur is the owner of Fox Media Tech and author of My New Microphone. He's an audio engineer by trade and works on contract in his home country of Canada. When not blogging on MNM, he's likely hiking outdoors and blogging at Hikers' Movement (hikersmovement.com) or composing music for media. Check out his Pond5 and AudioJungle accounts.

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