Being a regular cyclist every day that doesn’t heavily rain or snow, I’m shocked when I see fellow cyclists ride around wearing earphones in both ears. It was nice to read this article in Slate about why it’s stupid to do so, especially missing the cues about vehicles that are not in your line of sight that only come from hearing.
But even a burbling sonata can prevent you from picking up on subtler cues, and cyclists need all the cues they can get. Cars have air bags and crumple zones. Bikes do not. Cars have side and rearview mirrors. Most bikes don’t. Cyclists must crane their necks and look backward constantly. If your head and your front reflector aren’t pointing in the same direction, then auditory signals are essential to staying upright.