I haven't read everything, but thought I'd give my 10 pence worth anyway
If you want to listen to music while cycling...
then this is for you! Get a bike speaker! I have a DIY version, which was great for my commute. Not only can you still hear the road...you can share your fantastic taste in music with other people!
On the 'deaf people can cycle' argument. I believe that when you loose a sense, your other senses become more heightened? As the person is used to not being able to hear anything, they will be more aware in other ways. From experience, if I listen to music while walking I don't make as good judgements, or at least can't judge things that well (in a very similar way to how I felt while using a mobile phone while driving - did it once to see if it was distracting, hated it...I couldn't even work out if it was safe to pull out at a junction, so hung up after about 10 seconds).
Now, iPod earphones are so rubbish that you can probably still hear a lot. Probably a lot more than you could hear in my Dad's Jag, with the radio on a sensible volume.
I have also seen car drivers and bus drivers with earphones in, so this is far from a cycle only issue.
I bet a lot of the injuries are caused by cyclists who would have caused when anyway, due to their lack of road sense...they just happened to have music in at the time.