If the song "It's a Small World" has ever driven you bananas, then you've got an idea where this story is going.We've all had tunes stuck in our heads. Some of them remind us of childhood friends, places or events.A new study backs the obvious notion that a song can evoke strong memories. It also reveals that you don't even have to hear a song for the past to come flooding back. In fact, most people have an amazing ability to effectively hear songs that aren't even being played. Word powerThe new study involved 124 people, average age 19, who...