It has been around for a while as far as I know, I was introduced to the concept back in the '80s. It was called "cat belling." Memory leaks and memory pressure, frame rate drops (it was especially useful for that), texture loads & swaps, game AI processing. We used it for determing if the game was executing correctly by how often it passed certain check points in the code. Also tracking the number of sprites in play vs the number on-screen. You could listen for the rhythm of the various sections of the code, in what was to most people, a cacophony of noise.

After thought: I should probably try and work some of that concept in to my next music track release.