Theoretically, everything in the universe vibrates. So, it makes sense to Ed that when Irene falls into his arms on the DC Metro he hears her music. In Ed's world, the harmonious vibrations created by the various elements making up a person create music. He then takes this one step further and when he hears the music, he assigns a familiar song to it. Since a person's composition changes over time, so does their song. But, you have to be paying close...