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Step 4: Build a Better Wall A typical 2 x 4 wood-stud wall with fiberglass insulation has an STC rating of 38. But a quiet media room requires special construction techniques. Double-stacking 0.625-inch drywall on both sides of a 2 x 4 wall increases the STC rating to 43 to 45, while staggered-stud construction increases the rating to 46 or 47. A double wall with an air gap in between produces a rating of 56 to 59. "Floating" the sheetrock on a resilient channel can dramatically decrease sound transmission. Also, installing dense acoustic matting material such as Acoustiblok beneath the sheetrock can give a standard 2 x 4 wall a rating of 52. Quiet Solutions' QuietRock claims an STC rating up to 80 and meets THX's certification for sound isolation.

Step 5: Windows and Doors Windows let in light, are highly reflective, and provide another way for sound to get in and out. If you must have windows, seek out specially constructed ones designed with sound treatment in mind. Your room needs to have a door, but buying the right one will make all the difference. Select one with solid-core construction that sits in a specially designed frame and threshold that seals sound in. For the ultimate in sound control, build a dual-door system - like an airlock - that can keep nearly all sound from escaping through the door.

Step 6: Minimize Penetrations If there are any cracks or gaps in your walls, sound will leak through them. Any penetrations in the walls or ceiling such as recessed lights, HVAC registers, or electrical outlets also create pathways for sound to escape. Make sure any penetrations are properly sealed. In-wall/ceiling speakers need to be installed in specially designed acoustic enclosures that not only improve their performance but keep sound from blasting into other areas. If the theater shares a wall with another room, make sure there aren't penetrations on both sides in shared stud bays.

Step 7: After Construction Once the walls for your theater are built, your sound-treatment options are more limited. Thick padding and carpeting can help to soak up sounds, and sound-deadening mats underneath the flooring are especially helpful for keeping sound from leaking into any rooms below. Thick drapes will also absorb some sounds, but mainly in the mid to upper frequencies. There's only one real cure for boomy bass heard in other rooms: Lower the volume.

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