How?

I wanna know how people tune others out while being in social situations? I'm a social butterfly and love being in a crowd of people and going to church and being out and about but occasionally I'd like some quiet time while being out and about without people bugging me. I've tried having my earphones being in my ears, rocking out and people obviously know I'm busy but for some dumb reason people don't get it. How can I do that without being a jerk.