Zombie cyclists

Just a quick note to say the head phones you get with iPods are shit and therefore you can use them safe in the knowledge that you'll be able to still hear outside noise, buses, trucks, cars etc and the music will be a faint hissing beside it

Doesnt it also depend on the type of earphones you use?
I know that you can get cheap/expensive total block out (passive)/noise cancellation (active)/expensive external noise (opposite to the block out ones)

I may probably be wrong but if you have cheap ones or the ones that let ambiant noise in, you can still hear the noises around you. Blocking out sound may end up cacooning you in your own world.

This is right, I reckon. I've pretty much always listened to music when cycling, unless I'm specifically wanting to think about something I'm working on. But when I bought some new earphones and they were inadvertently those cancelling-out-noise type, I got a bit freaked out by the diminishment of my peripheral hearing, and went back to the shit ones. Safe in the knowledge that I can have them up as loud as they can go and still hear anything going on perfectly adequately.

My Dad's deaf, and he's a keen cyclist. I don't think, when listening to music, that I 'compensate' any less than he does when just riding about.