The ” headLamp” consists of “about 300 leds soldered into a metal colander (like you use for straining noodles)” and are “wired to a circuit and controlled by the [computer’s] parallel port”. Video demonstration after the jump.
The iTunes plugin is written to accept sample data from iTunes when a song is playing, which takes the form of an integer between 0 and 128. The plugin operates under the assumption that a rhythmic beat is likely to send a higher value, around 120. If a sample value over 120 is sent, the plugin changes the lamp’s state based on preprogramed patterns like rotations, buildups, etc.