I think I covered this above.

My view is that you are reducing the chances of you being able to protect yourself a bit from someone else doing wrong. Doesn't mean you will get hit if you ride with, nor that you won't get hit if you are headphone free. possibly a tiny fraction of a change from very very very unlikely to happen to very very unlikely to happen.

The discussion about pace lines I find really odd. I ride without headphones and do 5 hour solo TT rides some weeks, or in a group others. When we ride as a group there's not a lot of chat for much of the ride, but throughout the person at the back will call out 'car back' to let riders up front know there's a car approaching so be mindful to keep to the side, not peel off. And that person isn't riding along looking back, they are using their ears. Sidenote that it used to be a lot easier to know there is a car behind - on descents now then with slight wind noise from helmets and modern cars being so much quieter, you can have a family SUV or saloon behind you and not realise. Again, headphones may impact some people some occasions, but won't impair everyone all the time. This isn't a simple binary situation like tubs/clinchers or disk or rim. (#pink)