An unintended—and unpleasant—consequence of installing a good quality surround-sound system in a new home is the transmission of that sound throughout the house through walls, floors, joists, studs and beams. Some builders plant a big-screen TV display and a moderately good sound system into a family room and call it a home theater, which it is not. Then the homeowner finds that when junior is watching a late-night movie on HBO HD, the whole family gets to partake in the experience, like it or not.

The primary offenders are subwoofers, although sounds in the mid- and high-frequency ranges are also picked up and transmitted through the structure. This can be a problem with whole-house audio systems as well. Music may be on in one room, and, depending on the quality of the installed speakers, some of the sound can be heard—and felt—clear across the house.

Up to now, mitigating the problem of sound leakage from room to room has been the complex and expensive construction of a “room within a room.” Walls, ceilings, and floors are built within a room and isolated from all structural components with a sound absorbing material such as rubber. This is how high-end home theaters are built.

Two companies with new home builder track records offer relatively simple and low-cost ways to deal with sound leakage. The simplest is sound-deadening drywall from Quiet Solution LLC, a Sunnyvale, Calif.-based company that specializes in sound management ( Its QuietRock 525 drywall, used in place of standard drywall, decreases sound transmission by roughly 70 percent, in terms of what the human ear actually hears. The QuietRock is a combination of gypsum and a ceramic cement in a constrained layer damping system. “It doesn't want to vibrate,” says Kevin Surace, the company's CEO. “You just put it up and screw it into the studs.”

Varying quality grades in QuietRock's line progress up to a THX-certified product that, when properly installed, renders a room almost soundproof. Most practical for production builders might be the 525, which can be installed in place of drywall, with no other structural modifications for up to $3 per square foot, depending on volume purchased. This compares with 30-to-60 cents per square foot for standard wallboard, depending on locale. It can be scored, snapped, screwed, and taped just like drywall. And it can be specified for only certain walls.

The wallboard can also be used on ceilings, and it is more effective when used on both sides of the wall or with staggered-stud construction. Still, it can not address sound transmission through the floor. The company does offer floating floor systems that do, but these are not practical for most production home building.

Another product, Acoustiblok, from Acoustiblok, Inc. in Tampa, Fl., ( does claim to be able to handle floor transmissions. Acoustiblok is a heavy mat material that is hung on wall studs and wrapped around floor trusses and beams to isolate them from wallboard, ceilings and flooring. It weighs about the same as lead, according to Lahnie Johnson, president and founder of the company and the inventor of Acoustiblok, “it will do as much sound stopping as 12 inches of poured concrete.”

Cost for Acoustiblok is about $2.40 per square foot. The company also is readying a new ceiling tile that Johnson promises will complement Acoustiblok installations, and will carry the highest sound absorption rating of any tile on the market.

Either product should provide production home builders with the wherewithal to at least mitigate sound transmission through the structure of a house. Although neither comes close to room-within-a-room construction, both can help avoid complaints from new homebuyers for a reasonably moderate upfront cost.