Most people I know own a subwoofer.
I should clarify. Most of my friends these days live in unattached houses, either owning or renting. I think we all know that having a subwoofer in an apartment creates a problem.
Remember your roommate in college whose computer-attached subwoofer was annoying because it was the only thing you could hear coming through their closed door? I certainly do.
Bass waves behave differently than the rest of the waves you can hear. Bass waves are much, much longer, and because of that they don't reflect off of the walls — they go straight through.
Also, they tend to sympathetically vibrate your walls, which only amplifies the resonances and ringing in bad bass. The vibrating walls even make noise themselves, like giant speakers.The floor can vibrate as well, since the heavy subwoofer rests on it, and if you've got someone living below you, the bass leak may be worst for them.
The bottom line is that in apartment settings, it can be nearly impossible to create an environment where bass doesn't leak out and travel to your neighbor's eardrums. That's the cause of most worries relating to subwoofers, but I also care about the fact that the quality of the bass is ruined in an untreated room, and you always wind up turning up the sub too loud to compensate for leaks and dropouts in the bass spectrum caused by what's called "room modes."
There is hope, my apartment-dwelling friends. It's kind of counterintuitive, which I think is fun. The solution is to add more subs.
You read that right — add more subwoofers instead of acoustically treating your listening room or turning it down.
When you add another subwoofer, you now have two drivers playing the same signal, and you can turn the power of each down by half. You're putting less intense vibrations into the room in a single spot, and you're also addressing the issue of room modes, removing some of the dead areas in the bass.
Now here's the kicker. If you place the subs facing toward you at equal distances, their waves will arrive at your ears "in phase," meaning the peaks and the troughs are perfectly aligned and therefore double up and add 3 decibels to the perceived volume at your position. Which means you get to again turn the sub volume down. It's like when you're wakeboarding and you wait until two waves hit and double up so you can jump higher than you could off of one wave.
Lastly, if you make sure the subs, pointing toward you and equidistant, are placed a little asymmetrically (not in the middle of a corner or the middle of the room), you will further eradicate those pesky room modes, and you might be able to turn down the subs even more.
Best of all, you'll be listening to better bass, and everything else in the music will come out — details and the spatial stereo stuff will be more vivid. And you can say goodbye to the loud banging on the walls from the poor guy next door.