Time, place, and the associations of music in our psyches and who we are, who we were and who we will be. I had the experience this afternoon of hearing a song I hadn't heard in awhile, and it brought me right back to the teenage mindframe that I had developed, nurtured, known and loved.
Now people have beaten this "music is the soundtrack of our lives" (thanks "Dick" Clark) horse to death a long, long time ago, so all I can do is pitch in my two cents (sense) and see where it goes.