Managers who deliberately create environments where headphones are mandatory should be brought up on charges.
Basic rule of thumb: If your headphones are loud enough to block out ambient conversation, they're damaging your ears. In 20 years, deafness is going to be associated with programmers in the same way we associate black lung with coal miners.
Also, I'm happy for you that your brain is only derailed by particularly loud ringtones or people tapping you on the shoulder, you lucked out on that one! But my brain is different: https://en.wikipedia.org/wiki/Misophonia