Acoustic Treatments

No matter your space, the microphone will always capture the room. You might use specially designed microphones to mitigate this and capture as little of the room as possible, but the reality is that you can't entirely remove the room from the equation. Let's discuss how to turn our bad-sounding rooms into better-sounding rooms by adding acoustic treatments.

Let's start by identifying what the issue is. Sound from your speakers does not travel in a straight line. They travel in an omnidirectional pattern, spreading sound waves in 360 degrees. Of course, your ears pick up the signals directed towards your head, but they also pick up reflections from the walls. These reflections create various problems, each requiring specific solutions.

The following chart identifies the most common problems experienced in rooms. Note that this room is rectangular, and if your room has angled ceilings and non-parallel walls, you might require more research to figure out how to tackle your room's issues.

Let's clarify why delayed sound waves from the walls create a problem. To understand this complex problem, we must understand the phase relations of delayed signals. Sound waves can interact with each other to create sums. This is actually how music works. When you listen to a song, you only hear a single sound wave, yet your brain can decipher this signal to different parts, such as the instruments and vocals. The result is a louder signal when we add the same signal to itself. But, if one of the signals is delayed, we get strange results. There is a limit to how much delay there can be in the signal before the original signal completely cancels out. Think of it as adding a positive integer to its negative ( -8 + 8 = 0), and the following graphic depicts this issue.

The signal that bounces off the walls mixes with the original signal as it arrives in our ears. This doesn't cancel the original signal altogether but cancels some of the frequencies, creating a new, false signal. If any music is mixed in a room with reflections like this, the engineer will think they are going crazy because some frequencies will sound so much louder than others, and some will practically not exist. These mixes sound horrible in any other space because the engineer mixed the music to their room rather than mixing in by using truthful sound signatures.

This is such a detrimental issue that we recommend you attack this first. The points (A) from the above graph, depicting reflections, should be treated before anything else. You can have a friend put a mirror on the wall between your head and the speakers and move it until your eyes meet the center of each speaker. Once you can see the speakers, mark those points on the wall. That is where you should place your acoustic treatments. Be sure to read until the end of this article because we will cover what types of acoustic treatments to get.

An equally important issue present in many rooms is the flutter echo from the back walls. This doesn't happen in every room, but there is a good likelihood that you might have heard this before. You can clap your hands loudly to see if you hear any echoes right after. It is called flutter echo because it happens very quickly after your initial clap. If your room has this issue, I recommend you also put some acoustic treatments on the back walls. Even if your room doesn't suffer from flutter echo, you will still benefit from this treatment because the bass frequencies tend to bounce off the back wall and come back to your ears, creating a sense of extra bass in the room.

This bass topic leads to points (C) and (D) on the reflections diagram. Corners are notorious for collecting bass frequencies. I can't explain why and how, but the corners of your room can make you think there's more bass, leading you to cut bass in your mixes, making your mixes sound thin. Point (D), right behind your speaker, is another major issue. Ideally, you would put your table and speakers in the middle of the room, but no one has that much space. So, the bass frequencies from the speakers collect and reflect from the back walls, again creating a sense of the abundance of bass, leading you to cut back the bass frequencies in your mixes. We highly suggest moving your speakers away from the walls, placing proper bass traps on the corners, and placing acoustic panels behind your speakers.

Your ceiling is also problematic. Sounds reflect from your ceilings, just like the side walls, creating phase cancellations and comb filtering. We suggest you hand some acoustic treatments from your ceiling to mitigate this. We will recommend some products at the end of this article. It is easier said than done but trust us; it makes a huge difference.

Something many engineers tend to ignore is the reflections from your table. Your table is a flat surface, just like your walls, reflecting sound waves off of it, delaying the signal and creating phase issues. We recommend tilting your table towards the listener by about 6 degrees. Doing this makes the table reflect the sound waves at such an angle that the delayed signal passes under your head. You can put some folded paper or cardboard under the far legs of your table. Just ensure you don't tilt it so much that things start falling.

There it is. We've made it. I don't want to cover diffusion in this article because we don't recommend diffusion for most rooms as it can create more problems than it solves, but also good ones are expensive. We will cover that in another post.

Let's talk about what types of acoustic panels to buy now. What is worth it? I will tell you right away that you should avoid the thin acoustic foams sold on Amazon and other retailers. Foam is an expensive material. For acoustic treatment to be viable, it needs to be thick. Thin acoustic treatments only absorb high frequencies, not low frequencies. The majority of the rooms don't have issues with high frequencies. Low-frequency absorption requires thicker treatment options, at least 2 inches, but ideally 4 inches. The material used in most acoustic treatment panels is Owens Corning or glass mineral wool. Other materials are out there, but these are the most common ones. They are cheap and effective. For the walls, we recommend you get 4-inch thick panels. For the corners, you will need large and heavy bass traps. I would say get the biggest ones you can afford and fit in your room, but that would be bad advice. To ensure you are treating everything correctly, you can use a microphone and this incredible, free software to find the problematic frequencies in your room. Every time you install a new treatment in the room, you should rerun these tests to make sure you are moving in the right direction.

There's so much more to acoustic treatments than we covered in this article, including room modes. These complicated topics deserve their own posts rather than being squished into this article. Look out for more in the coming weeks.

If you are in the market to buy acoustic panels, we cannot recommend GIKAcoustics enough. They are reliable, effective, affordable, and helpful. They can help you pick the right panels for your room via their personalized shopping guides. They will match you with a pro who will recommend what kinds of treatments will be the most effective. Click here to purchase your new acoustic panels and help us with a small kickback.