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4.2 Acoustic Treatment Panels

Acoustic treatment panels absorb sound and cut down on echo. Installing them can make your space much easier to work in for both recording and editing. In this lesson you will learn where to position acoustic panels for a neutral-sounding recording.

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4.2 Acoustic Treatment Panels

Acoustic treatment panels absorb sound and cut down on echo. Installing them can make your space much easier to work in, for both recording and editing. In this lesson, you will learn where to position acoustic panels for a neutral sounding recording. When it comes to acoustic panels, a lot of people think of foam. You've probably seen foam panels in pictures, and sold in music instrument retailers recording department. The problem with foam is that it doesn't offer any meaningful absorption below one kilohertz. Using foam for sound treatment is not effective because you will still have an issue with low frequencies. A better material to use is rigid fiberglass insulation or mineral wool. I prefer mineral wooll because it offers very similar if not better absorption properties. It's less irritating and it's more cost effective compared to fiberglass. Mineral wool, also known as mineral fiber, rock wool, or stone wool is a product that is made from molten rock that is spun into a fiber in a process similar to making cotton candy. It looks similar to fiberglass but is more dense. Two-foot by four-foot rigid mineral wool and fiberglass boards are the two most common types of materials used for commercial sound absorption panels. Most of these products are frames made out of wood or metal that go around the outside of these boards. The frame provides a place to attach hardware for wall mounting. And then these panels are wrapped in fabric for a nice finished look. These panels are quite easy to make, and you can check out a few tutorials that I created on for more information on how to make your own. The panels can be made for a fraction of the price of commercial panels, but I understand that the DIY solution is not for everyone. Before you figure out where to place your panels, you wanna make sure that you are positioned at the optimal spot in the room. The listening position should be about 38% back from one of the short walls, and centered between the two long walls. If you can't get your listening position exactly at 38%, just make sure that it's not at the 25, 50 or 75% positions, because at these positions you will experience huge peaks and dips in the low frequency response. Once you settle on a listening position, your next task is to create a reflection free zone. The reflection free zone, or RFZ, is a pretty simple concept. The idea is to prevent early reflections, also called first reflections, from interfering with the direct sound from the speakers. This interference happens when the sound arrives at your ear at more than one time. One of these sounds comes directly from the speaker, and the other comes from the sound of the speaker bouncing off the walls and hitting your ears at slightly different times. You might not think that this makes a huge a difference but it can be very dramatic. In order to determine where the RFC is, get into the listening position and have a friend take a mirror and hold it up to the wall. Any place that you can see either part of the right or left speaker needs to be treated. The ceiling is also part of the RFC and should be treated as well. You can find the position here by using the same method, but this can sometimes be a little bit difficult. Instead, you can hang the panels just above the listening position, or along the same axis as the side panels. When I mounted these four panels in my room, I noticed an immediate improvement in the sound. Everything coming from the speakers sounded tighter, clearer, and the imaging between the right and left speaker improved tremendously. Outside the RFC, you also need absorption. Depending on the size of your room, this can as much as 50 to 30% of the untreated wall space. Smaller rooms will need more. The panels should be spaced evenly in the room and offset so that the panel on one wall is pointed at the space between panels on the opposite wall. This will help to prevent a flutter echo between parallel walls. Some rooms are going to be a little bit more complex than your average rectangle. And you will have various challenges in placing your panels, but the idea is to be prepared to add enough panels to make the space work. Just treating the RFZ and adding a few more panels is going to make a huge difference in the way the room sounds. Like I mentioned before, the benefit to treating the room is that now it sounds much better for editing and mixing and recording. Let's say that you did some room treatment, but you were still hearing a little bit more room reflection than you wanted to. Here are some options. If you have any panels left over, you can take a panel and rig it up so that it is positioned just behind you when you are recording. As long as your panels are not super heavy, a photographic light stand would work well for this, as they are pretty strong and lightweight. Alternatively, you can take a few moving blankets and hang them just behind you when you record. To hang them, you could get a sturdy piece of PVC pipe, or even a shower curtain rod, and clamp the blankets to the pipe. To support a large rod with a fairly large curtain, you're going to need a pretty beefy stand. I like to use a C-stand with a grip head and boompole hanger, to hold the shower curtain rod. With a sandbag or two on the bottom, this is a very stable and safe solution. If you position this a few feet behind your recording position, it will make a big wall of sound absorption. It may not work very well in the lower frequencies, but as long as you are a few feet away from any walls, this should work very well. Now that you understand the basics of treating your space for editing and recording, you are ready to move on to the next chapter in this course. In the next chapter, you are going to learn how to prepare, set up, and record your voiceovers, so check that out coming up next.

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