mp3 players while riding, especially on busy roads, are not recommended. when you're plugged in, you won't be able to hear the traffic around you. and that can be quite dangerous. also, you might get caught up in your music and lose concentration.
remember, we are sharing the road with cars, and you know how malaysian drivers can be. and since we are almost invisible to motorists' eyes, it helps to be as alert as we can.