If I have something I'm interested in and really need to focus on it, I am almost immune to distractions like this. If someone bumps into me, however, they just might get a defensive response completely out of proportion from the 'offense' of bumping into me.
If I'm just waiting my turn or something and there's nothing to keep my attention away from the personal space invasion, I can get very impatient and it causes quite a bit of stress to try to contain that emotion. Standing in line is like this, I really hate it.
I see people in crowds all touching each other and rubbing past each other. I really don't want to to play that alien game either. It's not the hideous orchestra of disgusting smells either, because I'm usually doing an internal stim, grinding my teeth or sucking them dry or something, to alleviate or at least block most of that. I don't want to give up the control I try to keep over my own body. If you're in a crowd like that, no one is in control of anything.
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It's just music for me. The other stims don't work.