Music. We are surrounded by it; MP3 Players, Radios, Bands. Music played at public places is usually pagan except around Christmas time. The first time you hear anything about music is, I believe, Genesis 4:21. The people at my orthodontist's office were playing the most horrendous screeching-singing music that I've heard for a long time.
I mainly listen to Christian (and instrumental) music. But I don't really care much for, Casting Crowns, even though what they say is (mostly) great. I personally like Christian Hip Hop (CHH) like 116 Clique, Lecrae, Flame, etc.
Casting Crowns and Lecrae are both Christian, but have different styles. They both reference the same faults/needs of today's culture. For example: environmentalism.
Casting Crowns in While You were Sleeping says "United States of America ... save[s] the trees and kill[s] the children..."
Lecrae in Blow your High says "... worshiping a tree instead of worshiping the King..."
I like the style of rap, but I like rock too, some other styles are cool too.
Music can be something people listen to way too much, or not the right kind. It shapes how you feel as you listen, and maybe for long periods of time; sort of how certain lighting makes a movie creepy, and if you watch too many creepy movies it does not help how you act.
If I listen to Relient K, Sanctus Real, Switchfoot, Skillet, and the like, for about 0.75 hours or more, I start getting a bit depressed, dreary, and quite sick of it. If I listen to one style for 1.5 hours or more I get really sick of it.
I think the music you hear might change you more than you'd think.