The title Clang is an homage to Arnold Schönberg's compositional technique Klangfarbenmelodie (tone color melody). Traditionally, the term 'melody' implies a change of pitch over time. Tone color melody, on the other hand, results from holding the pitch constant and instead changing timbre over time. In Clang, pitch, represented as a MIDI key value, is held constant, but each new note is preceded by a MIDI program change, meaning that each note is played using a different instrumental, vocal, or percussive sound.
In Clang there are anywhere from one to eight "clang generators" running at any given time. Each generator chooses its pitch (MIDI key value) and timbral palette, of which there are three: an extensive collection of instrumental and orchestral sounds, including sound effects; a collection of basic vocal phonemes as recorded by two linguists, male and female; and a large collection of wooden drums, played with the hands. The basic decision that each generator makes from one note to the next is the specific sound to choose from its palette of sounds. It makes this decision based on the output of an iterated non-linear dynamical system called the Standard Map, a textbook example of a chaotic system.
Corresponding to each timbral palette is a specific graphical representation of the decisions made by each generator. For the vocal palette, each note is represented as a horizontal or vertical bar arranged around the inside of a square. The bars are grayscale colors from white to black, on a red background. For the instrumental palette, the bars are arranged radially in a circle around a central point. The bars are secondary colors on a blue-green background. For the drum palette, the bars are arranged along the bisectors of a triangle. They are in tertiary colors on a brown background.
The image generated by Clang is projected onto a double layer of theatrical scrim—a thin, partially translucent material used for special effects in stagecraft. The scrim bestows a parchment-like texture on the visual image, which I find attractive. Here are a couple of examples: