I have been pondering this one for a while now.
I first got a CD player (more recently and mp3 player) because I wasn't interested in hearing the school kids f**k this and f**k that or talk about how they got drunk, or about anything else, whilst reading my book on the tram. It's a nice little insulator, and I can at least feel a little happier I'm using less electricity with the smaller battery.
But think about second hand music noise. One of the other things I never liked pre-music (or when I have flat batteries) is the thump, thump, thump of the souless garbage some people insist listening to with the volume set to 11. I notice recently that Pete Townsend made a plea for people to turn their music down - if anyone knows about industrial deafness, its a rockstar.
This noise can lead to an arms race, I turn mine up so as not to hear yours, and so on. Quite apart from lacking any sense of preservation of the faculties, it can be plain rude. Think about this as you bop along in a public place.
And then there is mobile phones ... I don't want to hear about your business deal, that you are on the tram and are coming home. Why do people tal 10 times louder on the mobile/cell phone? There is no long string at either end, maybe you should just stick your head out of the window and shout to the wife?
Well, I guess technology doesn't make one ruder or more virtuous, just gives us a chance to show off (can you see the irony in this statement! :) )