Even the greatest roommate sex-overhearing relationships can get tired. So mix it up once in a while: When you lean against your wall to hear your roommates' grunts and moans better, try leaning in a new position!
Chocolate sauce or mango slices can be a great way to reinvigorate your senses while you eavesdrop. Or try alternating sips of ice water and hot water while you listen to your roommates intimately pleasure each other.
Light some candles, make a playlist, and make a night of it. Tease yourself, slowly getting closer and closer to your roommates' door until you feel like you're going to explode. (But make sure you're still far enough away that if they came out of the room, you wouldn't seem creepy.)
Dirty talk can be a sexy way to heighten your enjoyment of your roommates' sex life. Verbalize what you'd like your roommates to do to each other. If you suddenly get nervous that they've heard you, loudly play a pop-up ad on your computer so they think you're just watching porn.
Experiment with roleplay! Pretend that the sex noises are coming from your room, and that you are a person whom literally anyone else is attracted to. Let your imagination run wild as you fantasize about having the kind of incredibly vanilla sex your roommates are having just so you can experience human contact. Then cry for a while.