I hooked up my trusty old Logitech speakers to see if they still worked. They did, so I booted a game and sheepishly turned the volume way down in fear of annoying my neighbors, immediately remembering why I had these stuffed in a closet for almost 10 years.
Even if I lived in a soundproof house in the middle of nowhere I'd still be self-conscious enough to just use headphones instead 
I'm almost forty and still have trouble remember to make sound when I walk around other people. Some childhood survival skills never go away.
Me too. People say "you scared the shit out of me" a couple times a month, and I'm usually not trying.
I had a roommate who almost requested that I wear a bell around my neck.