Teenaged Americans will more readily turn to YouTube to listen to music than they will any other source. This according to a new study out from Nielsen Music 360, which found that, though radio remains the most popular medium for discovering new music, Google's video streaming site is more popular than radio, iTunes, or CDs when it comes to listening. The study also revealed that nearly half of teens have radio apps on their smartphones and that digital music has surpassed physical CDs in terms of perception of value.