I have another piece of fishtank software which has little bubbles going up, making sounds as they go. It's not on Newgrounds, though. I used to have sound on this one. The farther a swap operation, the deeper the tone. It sounded like elektroplankton.
I got the idea for this when I got the idea for a huge screen wall, like 15 feet wide and 7 feet tall. Then I thought "it's going to need something for when it's not running." That's where this came from. Sticking to that original vision, I have removed sound from the movie. I did that because, well, it'd be annoying to have "beep, boop, beep" going on and on.
But you're right, it should have some sort of granular synth or something behind it which changes depending on how sorted it is.
Also, it *is* sorting numbers, but the numbers are represented in the height of a rectangle. The taller a rectangle, the bigger the number.