When you share a space with roommates, putting up with each other's noise—much like having your food mysteriously disappear from the fridge—is just a fact of life. But there are still ways to drown out roommate racket without living in headphones 24/7 or taking on pricey renovations that'll ding your security deposit.
A reader recently sent in a two-step tutorial to Apartment Therapy for an easy way to keep sound from coming in—or going out of—your bedroom, all for a price tag of $40 or less. It works like this: order a vinyl top threshold with aluminum casing that matches the width of your door (you should be able to pick this up on Amazon or at your local hardware store), and wedge it into the bottom of your door frame—it should stay put without any extra glues, screws, etc. Once that's in place, take half-inch-wide adhesive weather strip and stick it around the remainder of the door frame. This way, when you close your door you'll be sealed in tight against outside noise.
The reader reported a difference of 40 or 50 decibels with this method (as compared to having the door wide open), and hey, in the battle to stay sane while living with roomies, every little bit helps. Now, if only it were this easy to get them to remember to buy toilet paper...