Treating Your Listening Environment

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Article written by Ford Heacock from Fire Breath Records...

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99% of us that consider music either a hobby or slightly more so wind up in less than ideal spaces to conduct our art. We might get stuck in a small, carpeted apartment room, an area with high traffic noise, or we might even have a tiny human crawling around our house whose critiques might be better off unheard. Compromises must be made for great living spaces versus great studio spaces.

When you listen to, play, or create sound in an acoustic space you are simultaneously shooting sound waves in every single direction. Sound waves have a physical length and attribute and these attributes vary depending on their frequency. Low frequencies are longer & wider while high frequencies are shorter & narrower.

WARNING: INTERESTING SIDE STORY

Have you ever been in the shower or kitchen and caught yourself humming a tune (don't be shy)? Did you get really excited and curious when you discovered a certain note in that tune suddenly and mysteriously became 10 times louder than any of the other notes? This is what's known as a standing wave.

It's when the length of a sound wave (a certain note in our minds) exactly matches the length of the two walls we are singing between. The sound wave effectively layers itself, or amplifies, as it's able to repeat it's precise waveform over itself without going out of phase (more on this another time).

Now this is more difficult in larger rooms or spaces as the length of the sound wave needed for a standing wave would need to be longer, thus lower, and as humans, it would be impossible to create (unless you are the lead bass in the Metropolitan Opera).

However, it can be created by our sound systems!

WELCOME BACK TO THE ARTICLE!

While standing waves might be super cool and fun in the bathroom or kitchen, they are super uncool in the studio. The point of having a great studio is to have an accurate listening environment where all frequencies are heard as equally as possible.

This allows us, as mixers / recordists / listeners, to make correct decisions without being fooled by the room's acoustic qualities.

"So, how do I create an accurate listening environment? ? !"

I'm so glad you asked. And how convenient! I'm in the middle of writing an article about this very subject!

Ahem. So if you've ever had a friend who's at least somewhat into recording or have seen pictures of professional studios I'm sure you've seen the crazy shapes and materials thrown up on their studio walls.

These shapes and materials vary drastically but, for the most part, boil down to two types of treatment: diffusion and absorption.

ABSORPTION

I will start with the hands-down most common and least expensive way of treating your room, and that is acoustic foam. To summarize how acoustic foam works, as well as it's overall purpose, we can look to the wonderful Wikipedia for a quick synopsis:

"Acoustic foam is an open celled foam used for acoustic treatment. It attenuates airborne sound waves by increasing air resistance, thus reducing the amplitude of the waves. "

"The objective of acoustic foam is to improve the sound quality by removing residual sound in any space. This purpose requires strategic placement of acoustic foam panels on walls, ceiling and floors, effectively eliminating all resonance within the room. "

Experiment time! Walk around your room and clap. Listen for the reverberations and where the sound reflects. I have a high ceiling (13 ft) and when I clap I can hear a small "flutter echo" near the top corner. This is an example of something we want to eliminate (don't worry, it's gone now).

Our basic goal is to deflect and absorb (aka reduce the amplitude) sound waves from our speakers as much as possible. This will help prevent inaccurate reflections bouncing back into our ears during mixing (or listening, you hi-fi audiophiles). Remember, we want to hear our music as accurately as possible and NOT be tricked by our room.

Acoustic foam is also the most varied of materials and can range from ½'' to 4'' (or thicker) as well as egg-crate shaped to waves and to swirls. The point of acoustic foam is to 'absorb' stray sound waves that may have otherwise reflected off of walls, back into your ears.

The thicker the foam, the more absorption you will get and the more effective it will be. Typically, thicker foam will mean absorption that reaches more broadly across the frequency spectrum. Thicker foam can also help with lower frequencies, which tend to be the most difficult frequencies to tame. Remember when we talked about sound wave sizes? Lower are LARGER.

"We're gonna need a bigger boat. . . err. . piece of foam. "

Once your foam gets really big and thick, you start getting into the world of bass traps - but that is a little more advanced than what we want to talk about right now.

DISCLAIMER: TREATING YOUR ROOM WITH ACOUSTIC FOAM DOES NOT MAKE IT SOUND PROOF. WE ARE NOT SOUND PROOFING HERE, FOLKS. WE ARE 'ACOUSTICALLY TREATING'. Sound absorption is NOT able to significantly reduce sound transmission through a wall between two adjacent spaces; it is intended to improve sound quality and reduce noise levels within the room that they are installed.

While foam is very popular, there is a second type of absorption material that is a step up in price but, in my opinion, also a step up in quality sound control. Fiberglass acoustic panels. These panels are typically 4'x2' and are most commonly found in 2'' to 4'' thick variants.

If you use acoustic panels you will typically have to use only a couple on each wall. The equivalent sound treatment in foam could be 10-15 foam squares. In my studio I use acoustic panels on each wall and then fill in spaces above and below with foam. You can also get creative and make fun designs. Consider this revenge on that art project you failed in third grade. . .

While pre-built acoustic panels tend to be more expensive, if you are a handyman or handywoman, there are plenty of companies that offer DIY materials that you can build for pretty cheap!

DIFFUSION

Now that we've covered the world of absorption, I'd like to briefly cover a more advanced technique of acoustic treatment. Diffusion! I will now harken back to our good friend Wiki for an explanation much better mine:

"Diffusors (or diffusers) are used to treat sound aberrations in rooms such as echoes. They are an excellent alternative or complement to sound absorption because they do not remove sound energy, but can be used to effectively reduce distinct echoes and reflections while still leaving a live sounding space. "

As Wiki mentioned, the important difference with diffusion is that diffusion KEEPS the sound energy in the room. Unlike absorption, which reduces a sound wave's amplitude, diffusion scatters a sound wave to prevent echoes and standing waves and is a good way to treat a room who's natural characteristics you'd like to preserve.

I have 4 diffusors on my back wall as a means of treating my room without completely deadening it. I track in the same room I mix in and I wanted to keep a little bit of its natural sound. You'll have to experiment with your situation and see what works best for your room.

I've found that varying your arsenal of acoustic treatment works out in the end as they all wind up working together. Remember, I have high ceilings and wooden floors and already have a pretty "live" room sound. Each situation is different.

There are very detailed articles out there that go into detail about how to measure your room as well as figuring out what frequencies are more problematic in your space.

PLACEMENT

Now that we've covered both absorption and diffusion, we will now talk about the importance of placement. Without getting too detailed and nerdy on you, I will share a very easy and very simple manner to figure out where you should place that treasured acoustic treatment.

Our primary area to treat is the 'first reflections zone'. This is where your speakers are directly pointing and where the most energy will be focused. To find this spot, hold a mirror on the wall and slide it across until you see the slightest bit of cone from your speaker/monitor.

Do the same on the opposite wall. This will be the most significant help in treating your room at it is the most direct culprit of reflections.

Now as you should probably know, speakers do not shoot lasers and thusly, the energy dispersed from them goes everywhere; therefore treatment has to be everywhere (for the most part). Since we've covered the 'first reflections zone' we will now move onto the next most important area to treat. The back wall!

If you have a decent amount of treatment, this is where you should focus your energy after the first reflections are taken care of. The back wall is almost as important as the first reflection zone as it is what sits directly behind your ears. This is where you should place diffusers if you have them but foam and panels will do just fine.

Your next goal should be to treat the wall in front of you, or behind your speakers. Believe it or not but speakers emanate quite a bit of energy behind them as well. Try to keep your speakers at least one foot from the wall as any closer can risk low-end build up and more inaccurate sound waves.

Last but not least, if you are incredibly proactive with your sound treatment, aim to make a 'cloud'. As the name might suggest, an acoustic cloud sits about your head in the listening space and takes care of reflections off the ceiling.

Now in my case, I had to forego using a cloud because my ceilings are way too high (13ft!) for me to even attempt hanging anything from them. Clouds are also very tricky to get correct and require a decent amount of ingenuity with wires, screws etc.

Don't feel obligated to have a cloud; many great studios don't have them. But if you can, go for it! The sky is the limit. Heh.

That's it for now on acoustic treatment, hope this helps get your room into working order! Thanks for reading, always.
 
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