
My father once used to joke that to him all music sounded the same--of course that wasn't true and he enjoyed listening to classical, jazz, and rock (Robert Mapplethorpe's famous photo of Patti Smith hung above his desk for years). But his comment does raise an interesting point--why does music sound different and have produce different reactions in people? For example, the theme from Titanic made many cry, it made me want to run from the room screaming. My mother loved to play the recordings of Broadway shows, and most of that has no effect on me.
Of course some of it may be what we associate a certain song with in terms of when we heard it playing. The sound track of the Sound of Music reminds a close friend of the day her little sister threw up in a theatre when they were watching the movie (How Do Solve a Problem Like Maria ? has that effect on me on matter what) and if you ask myself or three high school friends what they think of when we hear the song Freebird, we would immediately say "Star Wars!" (before our first time seeing the movie, the theatre screened a short tribute documentary about the then recently deceased members of the band Lynyrd Skynyrd).
But our reactions to songs are much more complicated than that. A field of study called music cognition seeks to answer this and other questions. Ohio State University has a department devoted to this area. It hopes to discover how humans process music as well as the impact music has on a person. While this may just seem interesting it could down the road have serious applications. If music can indeed heal a person, then it would be regularly incorporated into a patient's therapy (for example, Congresswoman Gabrielle Giffords has been singing simple children's songs in order to help her regain speech. Information about her therapy can be found here http://www.telegraph.co.uk/news/worldnews/northamerica/usa/8349351/Gabrielle-Giffords-How-music-therapy-is-helping-her-recovery.html )
Aside from looking forward, another area of research is taking a look back to the origins of music. Using notations on stone tablets as well as period art, ancient songs are being uncovered. Its exciting to think that there are songs unheard for centuries just waiting to be heard again.