I had the good fortune of having this happen to me in the subway and not in an elevator which is a million times worse. I was standing up by one of the subway doors listening to my music when I let one go that I definitely felt but I had no idea how loud it was. I never found out, and I don’t think it was a smelly one so I’m guessing no one noticed. Had I been sitting down it would’ve been that much worse so I got off easy.