I commute through downtown Seattle every day & wear headphones. It's not very evident when you're in a car, but the wind in your ears is very loud. Loud enough that you can't use your ears to hear the cars behind as they approach. I've found a mirror to be a much more effective way to be aware of approaching traffic from behind.
The headphones I wear are not just some ear-buds -- they are seated in my ear & block out most ambient noise. I wear them to preserve my hearing.
Personally, I enjoy my rides more not having the sound of thundering traffic rolling past over the roar of wind rushing past my ears. I'm quite aware of the traffic around; I can still hear them as much as I would if I didn't have the headphones in. But it's much less intimidating (not to mention the music makes things even more enjoyable).
My experience is the opposite...hearing is so useful that I typically don't run the radio in my car and I like to drive with the windows cracked. I can often tell if another car is in my blind spot just by hearing it. I find this actually gets easier the faster I'm going.
I think it depends on personal experience. I had a car without a radio for years (stolen, too expensive to replace), so I got used to hearing the traffic around me. For the short period of time I bike commuted this translated really well. But if you're not used to using your hearing that way I can see how it would seem useless.
The headphones I wear are not just some ear-buds -- they are seated in my ear & block out most ambient noise. I wear them to preserve my hearing.
Personally, I enjoy my rides more not having the sound of thundering traffic rolling past over the roar of wind rushing past my ears. I'm quite aware of the traffic around; I can still hear them as much as I would if I didn't have the headphones in. But it's much less intimidating (not to mention the music makes things even more enjoyable).