I may be in the minority here but I've always been nervous when around drivers, walkers, joggers and bikers who wear earbuds & headphones on trails. As a result, I always approach these folks with extreme caution, pass at a snails pace and never use any product which covers my ears.
I apologize if this hijacks the OP's post but I had an incident yesterday while riding a local rail trail that I feel is appropriate to mention. I approached a middle aged man walking the trail while texting and wearing earbuds. A perfect storm of inattention! He did not respond to my bell, horn & shout as I passed at walking speed. Sure enough, he suddenly stepped sideways into me, knocking both of us to the ground! Luckily, there was no serious injury or damage. We both learned something from the accident, although he more than I.
From what I've read, pedestrians ALWAYS have the right of way in situations like this and I was in the wrong. The trail was 6' wide with a steep slope on one side and a high bank on the other which went on for over a mile. He was walking fairly fast and it would not have been possible to pass while walking my bike. Short of not being there at all, I don't know what I could have done to prevent the incident. Still, I would have been liable for any damage or injury.
In many states, driving a vehicle while wearing headphones is illegal:
Donning headphones while driving? Laws differ by state and some have more complex rules.
www.statesman.com
California Vehicle Code 27400 recently extended this ban to include cyclists and earbuds as well.
It is your responsibility as a driver to pay attention while operating a motor vehicle in California. Get your legal questions answered here.
theryanlawgroup.com
I'm not a fan of any regulation like this since it is overly restrictive and difficult to enforce. I think the problem would be better addressed through educating the public about the dangers involved while using restrictive hearing devices in public.