No matter how good your system, if you put it in an environment that's not geared toward good sound quality, even the best audio system will sound horrible. The room's construction, furnishings, and window and wall treatments have a massive impact on the quality of sound from your home theater.
Your biggest enemy is vibration. Just about everything - the walls, the ceiling, ductwork, suspended light fixtures - can vibrate. When a subwoofer produces its strong low-frequency acoustic energy, that sound wave travels through the room, hitting walls and ceiling surfaces. It's absorbed by the walls, which vibrate in reaction to this energy. This vibration then is conducted through any solid surface that it's in contact with it, including studs, joists, and flooring. From there, it travels up through the framing of the house, and you end up with a shaking house, making a special noise of its own. That's where you need sound planning (pun intended).
You want to try to control two major types of sound distortions:
- Intrusive sounds from outside your home theater (and, to be fair, sounds from inside the home theater that seep into the house)
- Sound reflections and refractions from the audio system itself
If you're building a new home from scratch or renovating, you have the opportunity to address the acoustics of your home theater at the architectural level. You essentially want to create a room within a room so that you can isolate and control the impact of the sound system's signals on the room itself. Seek to isolate your inside walls, ceilings, and floors from the rest of the house as much as possible.
Even if you don't plan to redo your entire home theater, you may want to add some interior sound treatments to deal with the sound in the room.
The following list gives you some ideas on how best to go about getting the acoustics of your home theater just right:
- Place studs appropriately, double your drywall, and insulate for sound. Avoid having the studs of two adjacent walls touching each other. By keeping studs from touching, you cut off a primary means for sound to travel between the room and the house (in both directions). You can also dull vibrations by adding a second layer of drywall.
- Apply soundproofing between studs and drywall. Consider adding a layer of soundproofing material between the studs and drywall. This material serves not only to suppress sounds going back and forth, but also as a vibration trap between the drywall and the studs themselves - further reducing unintended effects from your sound system.
- Apply soundproofing to the floor. Think about a floating floor, which is a multilayered floor designed to isolate your home theater from the rest of the house. For example, the topmost floating layer might consist of tongue-and-groove chipboard bonded to a layer of plasterboard. That in turn would be laid on a spongy layer made of some sort of mineral fiber. You could then glue the spongy layer to the existing floor or even mount the whole thing on its own joists.
- Apply a soundproofing system to the finished drywall. Adding specialized sound control panels to the walls can help control unwanted reflected sounds. (This reflected sound could cause a blurring of the sound image and lack of intelligibility.) Sound treatments also reduce the overall sound volume in the room, enhancing low-level dialogue and environmental effects delivered over today's high-quality audio systems.
The cost of the materials for soundproofing a home theater fluctuates, depending on what you decide to do. You can spend a few hundred dollars or upwards of $35,000.
Remember that your cheapest first line of sound defense is simply securing everything in the room and listening for things that add noise. Subwoofers can definitely shake things up; if that problem rears its ugly head, get some inexpensive isolation pads for the subwoofer's feet. Projectors can make a ton of noise, too; consider a special mounting for the projector that keeps the projector's noise contained.
