I'm not when it's normal noises, made by non headphone wearing people.

Normally people are conscious about the sounds they make and restrict them a bit. If you're coughing in a group, you try to do it softly, or you leave the room. Things like that. When people wear head phones this kind of subconscious self control seems to be a lot less effective.

I'm certainly not the only one to have made this observation.

I sometimes start audibly breathing with headphones on. Something I never do without them. So I won’t wear them around others when I can avoid it.

That’s aside from tapping I might not realize is making noise with headphones on, or a particular motion in my chair that’s making it squeak and I don’t know it because headphones, et c.

Loud breathing is one of my biggest concerns when wearing noise-cancelling headphones around others. Partly because I dislike hearing it from others and don't want to subject them to that, and partly because I don't want to sound like a smooth-brain mouth breather.