One of our modules required us to code a Processing sketch using sounds and visuals all inherent to Processing (ie: no external audio files or images). My program played a series of random notes within a scale and displayed a random size bubble in sync within a certain region of the screen depending on what note is played. There is also some interactivity, as you can clear the screen, pause it or click to play a chord. Here is an excerpt of the code and a very short video demonstrating the app in play. Processing Musical Bubble