i don't really notice the sound of people chewing ever. the quieter noises usually don't bother me. at one point i had this problem with my dad tapping his feet though.... when we watched tv he would tap his feet really softly on the floor, and it drove me insane.

yeah, i have headphones in at all socially acceptable times, including driving - drive a motorbike. people have said it's not safe to drive like that, but i get more distracted by the different noises when i'm not listening to music. music feels like calm noise.