Search one of the following locations to find the corresponding music:

Music #1: Anne-Claire's bookshelf 
Music #2 (Jasper, Bring The Car Around): The piano in the lobby of the 
         apartments where you first meet Charles. Note: Collect it before defeating
         Charles. 
Music #3 (Some Things Man Was Not Meant To Know): Defeat the final Boss. 
Music #4 (A Madman And His Violin): Left-hand drawer on the back wall in the 
         same room as Concept Art #4 
Music #5 (The Eight-Bit Precipice Of Darkness): The lemonade cart as soon as 
         you enter the panel with the FF Prime.