I occasionally get e-mails asking about cheap and easy ways to soundproof a listening room. Readers want to minimize the amount of bass and sound leaking into neighboring apartments or rooms in a house from their home theater.
Bona-fide soundproofing is neither cheap or easy. Anything short of building a "floating" (isolated) recording studio type listening room won't totally soundproof a room. You see, a floating room's ceiling, walls, and floor are acoustically and structurally isolated from its surroundings. Prices vary, but plan on investing at least $10,000 for a professionally installed floating room. After the floating room construction techniques, you can attain more limited success with double sheetrock on the walls. That is, install new double sheetrock walls with an air gap between them and the original walls. Double sheetrock can make a big difference, but it's still far from a cheap or easy solution.
A friend put a layer of lead sheeting under his apartment's finished wood floors to reduce bass transmission to the floor below. It worked, but I'm not so sure about the health concerns from living around that much lead.
But I do have a few tips to reduce sound leakage from one room to another, or between floors of a house or apartment that won't break the bank.
Before we go any further, let's define our goals: sound isolation isn't the same thing as improving room acoustics (I'll cover that in another blog).
Sound is transmitted from one room to another either through structure borne vibrations (wall, ceiling, or floor movement), or through the air. Thick carpets or wall pads won't do much in the way of soundproofing, but they may improve sound quality in the room.
I've used weather-stripping foam tape around the top and sides of a doorframe to create a better air seal that will limit the amount of sound that comes through a door. On the bottom of the door I've attached a plastic "door sweep." You'll need to set the sweep to just barely brush the floor as it closes to reduce the size of the gap between the door and saddle. The foam tape and door sweep will reduce the amount of sound that leaks out through the door; the better the seal, the less sound will leak through. Installed with care the sound reduction will be significant from those two tweaks.
The above tweak also works in reverse: it will block sounds from outside your room.
Bass is harder to soundproof than higher frequency sounds. To reduce the amount of bass a subwoofer transmits through the floor, try placing it on a 1- or 2-inch thick foam rubber pad. This technique won't work miracles, but it might help a little. For late night listening, try turning the subwoofer's volume down or off. Plan B: don't use a subwoofer at all; buy speakers big enough to produce plenty of bass on their own.
I have one other cost-effective solution guaranteed to stop your hi-fi or home theater's sound from annoying neighbors or family members: listen to headphones.
If you have any ideas on soundproofing, please share them in the Comments section below.