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Tip of the Day: Sound Isolation For Your Home Theater

by September 05, 2014

If you’re an Audioholic, odds are that from time to time, you like to listen to music or movies at “spirited” levels. Unfortunately, family members in another room might not be so enthused about your hobby if they’re trying to sleep, read, or perhaps get a little work done. What’s the answer to this dilemma? Sound isolation. 

Sound isolation involves a combination of techniques designed to limit the sound that enters as well as exits your theater. Think of it like wearing a pair of closed back "over ear” headphones: you can’t hear what’s going on in the outside world, and they can’t hear what you’re listening to. “I don’t care if people hear what’s going on in my theater” you say? No problem, but if sounds can easily leak out of a theater, they can leak in just as easily. If you’re trying to achieve a reasonably low noise floor (not to mention avoid ticking off your significant other), it behooves you to consider a bit of sound isolation when designing your theater.


Like this, but for your room.

Convinced? Great, so how do you do it? Sound isolation revolves around four key techniques, and together they limit how much sound gets transmitted through the walls, floor, and ceiling of your home theater. These techniques are mass loading, absorption, decoupling, and damping:

1.0 Mass Loading – Simply put, if you make your walls heavier, it is harder for that wall to move/vibrate, making it more difficult for sound to travel through to the other side.

2.0 Absorption – When you beat on a hollow drum, it makes more sound than beating on a drum filled with sand. The same principle applies to your theater walls: when you fill those walls with insulation, it again cuts down on the sound transmitted to the other side.

3.0 Decoupling – If you can create a ‘gap’ between two surfaces, it makes it harder for the sound to ‘jump’ from one surface to another, again improving sonic isolation.

4.0 Damping – If you’re able to use material to directly damp the vibrations of your walls, that is a big plus for sound isolation. One such material is called Green Glue, which is physically applied to your drywall and works to dissipate vibrations caused by sound waves travelling through the wall.

Green Glue

Green glue is applied to sheets of drywall, and serves to damp their vibrations.

As you might guess, the most successful sound isolation systems combine all four techniques. However, it should be noted that none of these are designed to address the sound in your room beyond potentially reducing noise. For that, you’ll need to turn to actual room treatments.

Credit: forum member diyhometheater


About the author:
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Steve Munz is a “different” addition to Audioholics’ stable of contributors in that he is neither an engineer like Gene, nor has he worked in the industry like Cliff. In fact, Steve’s day job is network administration and accounting.

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