Picture this: Half of the people riding the train with you are having loud, animated conversations on their cell phones, laughing or arguing with the person on the other end. The other half of the riders are blasting tunes on their music devices. The thought of such a scenario is enough to give you a headache. Which is why loud music and loud chatter are no-no's on a train.
By all means, listen to your favorite tunes. Just use earbuds or headphones. And keep the volume moderate so the person next to you can't hear the music through the headset. (Despite that popular song, it's not all about that bass!)
And try to stay off your cell phone. As scintillating as you think your conversation may be, no one else wants to hear it. If you do need to make a call, make it quick and use your "inside voice." Many people seem to talk louder on the phone than they would in person. To find the right level, move your phone a fraction of an inch away from your ear. This helps you to hear your own voice more naturally without one ear blocked by the phone, and so find a reasonable level for talking. Put the phone back up to your ear when speaking [source: Seid]. Better yet, tell your caller you'll phone her back when you get off the train and set your cell to vibrate.