Play around with the sliders and see how it affects the visuals and sound. You're hearing two sine waves, with their frequencies multiplied by the two sliders in the corners. The shape on the screen is those same two sine waves, with one representing the x value and one representing the y value. At the bottom it also shows the ratio between the two frequencies in simplified form. Simpler ratios produce more pleasant sounds. 2:3 is a perfect fifth, 4:5 is a major third, etc. Complex ratios like 16:15 sound pretty bad. I've also noticed that by changing the phase, the shape appears to be 3 dimensional. To be honest I'm not really sure why.
