You're a movie-and-music maniac with the latest, greatest home theater gear. You've just popped for a bright new plasma display, high-powered multichannel receiver, five (or seven!) speakers, and an earthshaking subwoofer. All you have to do is plug everything in, and it's time to rock, right?

Wrong. Unless you've prepared your room for the high-tech thrills to come, you could be disappointed. Electronics makers would like you to believe that an open checkbook is all you need for great pictures and sound — just move that fancy equipment into an expansive loft and you are there.

It's a compelling fantasy, but the truth is that no home theater system can be separated from the room it's in. Hardwood floors, huge windows, vast stretches of flat white plaster — the bare, spare spaces beloved by ad designers — look incredible as the backdrop for Gen Y sitcoms. They're also the stuff echo chambers are made of. Hard surfaces bounce sound around the room, destroying all the localization cues that movie sound engineers worked so hard to record. View a Hollywood blockbuster in a room like this, and it's Excedrin time.

Lesson One: Build it right
Luckily, there are cheap cures for the acoustical nightmares that are most modern architecture. If you're in the pre-construction planning stages, consider "staggered wall" construction. A simple but obscure building technique, it can substantially reduce transmission of sound from room to room, or house to house — especially bass signals, the bane of neighbors everywhere. Use two rows of studs instead of one, with those on one row offset from those on the opposite row (see illustration). Stuff the bays between the studs and the ceiling joists with standard fiberglass insulation, or acoustical-grade insulation if it's within your budget.

The air gap and lack of mechanical coupling between walls reduces sound transmission between rooms.

Stronger is better: Sheetrock is an egregious sonic offender. It's reflective through the midrange and high frequencies, and transparent to bass frequencies, like a drumhead — exactly the opposite of what you want in a home theater. "Sheer-wall" construction can help tremendously. Required by law in earthquake country, it means screwing plywood to the studs before applying the sheetrock. The result: stiffer, stronger walls that keep the bass in the room where you want it, rather than sending it down the hall and out the door.

You can exploit these two techniques — insulation and sheer-wall — even if you aren't doing new construction. Stripping a room down to the studs, insulating, sheer-walling, and re-sheetrocking are messy, time-consuming jobs, but the materials are cheap and the results rewarding. If you want to go this route, consider the services of a home theater installer to help you run all your cabling while the walls are open. Use flexible conduit with "pull wires" in it for future upgrades.