From When bugs sing:

By applying auditory display techniques to computer programming we have attempted to give the bugs that live in software programs their own songs. We have developed the CAITLIN musical program auralisation system (Vickers and Alty, 2002b) to allow structured musical mappings to be made of the constructs in Pascal programs. Initial experimental evaluation [Interacting with Computers (2002a,b)] showed that subjects could interpret the musical motifs used to represent the various Pascal language constructs.

For audio samples, see CAITLIN: Implementation of a Musical Program Auralisation System to Study the Effects on Debugging Tasks as Performed by Novice Pascal Programmers. My favorite is track 35, titled "Program A2 Normal".