Music in Fellowship Scene

In the scene where the Fellowship is camping out in the forest of Lothlorien after meeting with Galadriel, someone, I believe Aragorn mentions hearing music in the forest surrounding them and Legolas mentions that it is the Elves mourning a loss. It's an extremely beautiful piece of music but as far as I can tell, it's not on any of the three soundtracks.

Does anyone know what this piece of music is or if I'm just missing it on one of the soundtracks?