The mouse position (when clicked) gives a Supercollider Synth object a fundamental frequency, and then creates a SmileyFace object and sounds one of the four types of triads (major, minor, diminished, augmented).
The screen is divided into quadrants: the upper-left gives a “happy” major triad, the upper-right a “sad” minor triad, the lower-left a “neutral” augmented triad, and the lower-right, a “scared” diminished triad.
To run the sketch, open the processing sketch and Supercollider. Copy the SynthDef tab from the Processing sketch to the Supercollider window. Run the code in Supercollider, then start the Processing sketch.
Here is a little video of the sketch working.