But I had a pesky problem with my earbuds pulling out of my ears at times. Totally irritating. So I took one of my safety pins used to pin on my race numbers, and tied a loop in my headphone cord to hold it - see photo. Then I simply pin my cord to the back of my collar. Works great for listening and works great when you pull your earbuds out to talk to someone. They don't end up in your spokes.
Just make sure you still have enough safety pins left to pin your numbers on - so they don't flap. And no, don't wear the mp3 in a race.
When you are wearing the mp3, remember you can't hear what's happening near you. So learn to shoulder check obsessively and instinctively. Avoid unpleasant surprises.
Also, a piece of old inner tube makes a nice light, cheap, sweat-proof cover for the mp3. My custom unit cover has worked perfectly for years.
Keep on ridin'.