I'm also very sensitive to and easily annoyed by repetitive sounds (which I'm fortunate enough to be able to avoid for the most part). Things like whistling, drumming one's fingers on the table, tapping one's feet, chewing, etc...I can't stand it. I either have to ask the person to stop or I get up and leave the room. The same with loud, discordant noises. Drop a pan on the floor and you're liable to give me a heart attack (a slight exaggeration, but you get the idea. Scares the heck out of me and gives me palpitations). I often wondered why this was since I don't have any traumatic experiences associated with noise that would condition this sort of response. Then I read about Highly Sensitive People (HSP), which I definitely think I am. Apparently misophonia is fairly common among HSPs.

Ironically I love blasting loud music in my car as well. People are surprised to hear that I'm a heavy metal fan but can't stand seemingly benign noises like whistling. I think a lot of that has to do with choice and control over the situation. I choose to listen to music. I can turn it off whenever I want. I can immerse myself in the loudness of a concert because I know to expect the noise and enjoy the music already. With the other sounds, I'm at the mercy of other people's behavior and/or situations that I did not specifically seek out. That seems to be the difference for me.

(And just because I love heavy metal doesn't mean I want to hear it all the time. Even as a metalhead I prefer to spend most of my day in peace and quiet. )