Music for Piano and Computers
Christopher Dobrian

Artful Devices
Published by the Electronic Music Foundation

  1. Entropy
  2. Unnatural Selection
  3. Line/Phase Minutiae
  4. Unnatural Selection*
  5. Degueudoudeloupe
  6. There's Just One Thing You Need To Know*
*Daniel Koppelman, piano

Produced and engineered by Christopher Dobrian at the Gassmann Electronic Music Studio, School of the Arts, University of California, Irvine.

The performance by Daniel Koppelman on this disc was supported in part by a research grant from the UCI School of the Arts.

Tracks 1,3,4, and 6 feature the Yamaha Disklavier computer piano. The Disklavier was graciously provided by the Yamaha Corporation of America.

Compositions and computer programs copyright Christopher Dobrian.

This disc presents experimental music in which most of the composition and performance is done by computer programs. The intention is not for the programs to emulate traditional musical behavior, but rather to explore new musical possibilities implicit in certain paradigms of computation or computer decision-making.

Entropy was largely inspired by the following passage from The Open Work by Umberto Eco:

Consider the chaotic effect (resulting from a sudden imposition of uniformity) of a strong wind on the innumerable grains of sand that compose a beach: amid this confusion, the action of a human foot on the surface of the beach constitutes a complex interaction of events that leads to the statis-tically very improbable configuration of a footprint. The organization of events that has produced this configuration, this form, is only temporary: the footprint will soon be swept away by the wind. In other words, a deviation from the general entropy curve (consisting of a decrease in entropy and the establishment of improbable order) will generally tend to be reabsorbed into the universal curve of increasing entropy. And yet, for a moment, the elemental chaos of this system has made room for the appearance of an order...
The composition was conceived as a vehicle with which to explore ideas of information theory and stochasticism in an artistic way. It explores the perception of randomness and order (entropy and negentropy) in musical structure, and demonstrates the use of stochasticism not only as a model for the distribution of sounds in time, but also as a method of variation of a harmonic "order".

You can hear a brief excerpt of Entropy in MP3 format.

The notes of this piece were all chosen by a computer algorithm written by the composer. The algorithm takes as its input a description of some beginning and ending characteristics of a musical phrase, and outputs the note information necessary to realize a continuous transformation from the beginning to the ending state. Such a transformation can take place over any period of time desired by the composer (in this piece anywhere from 3 to 90 seconds). The input description is stated in terms of relative probabilities of different musical occurrences, thus allowing the com-poser to describe music which ranges between totally predictable (negentropic) and totally un-predictable (entropic), and which can transform gradually or suddenly from one to the other. The piece is performed by a Macintosh computer playing a Yamaha Disklavier piano.

Unnatural Selection is performed by an improvising computer program inspired by the computation technique known as a genetic algorithm, which takes a set of possibilities and generates new ones by recombining aspects of the old ones. The notes played by a human performer become a population of possibilities from which the program derives its musical material. The program "learns" the music on the spot, at the moment it is played by the human performer, and joins in with a synthesizer accompaniment it improvises based on the music it receives.

The first version is a recording of the premiere concert performance. The program receives data from a MIDI guitar played by Christopher Dobrian; however, the volume of the guitar is turned off, so all that is heard is the computer's response to that data. Thus, the human performer has the ability to influence the computer's composition in real time, but cannot wholly determine it.

You can hear a brief excerpt of this version of Unnatural Selection in MP3 format.

In the second version, pianist Daniel Koppelman improvises freely on the Yamaha Disklavier piano. The data from the Disklavier is interpreted by the program, which derives information about the pitches and rhythms being played, and produces a closely related accompaniment. Since the accompaniment is composed at that moment, the performer has never heard it before and is required to interact with this new sonic environment.

You can hear a brief excerpt of this version of Unnatural Selection in MP3 format.

Line/Phase Minutiae was composed for automated performance on a Yamaha Disklavier. The entire piece is an assemblage of sections composed by computer program, each about one minute in duration. The program composed two contrasting types of musical texture. One texture consists of repeated notes at seven different harmonically related tempi, which fade in and out of prominence according to individual curves of probability. The second texture is of rapid florid melodic figures covering a wide pitch range. These melodies were performed by the piano in realtime response to destination points indicated by the human composer.

You can hear a brief excerpt of Line/Phase Minutiae in MP3 format.

Degueudoudeloupe was programmed, composed, synthesized, and performed on a VAX 11/780 computer using the C programming language and the cmusic sound synthesis environment. Based upon parameters provided by the composer (a general description of musical attributes for a given phrase or section), the computer program calculates the complete musical score necessary to synthesize music that will fulfill the composer's description. The program specializes in composing music that includes metric modulations (sudden discrete tempo shifts in which the duration of a specific rhythmic value in the first tempo is ascribed a different rhythmic value in the second tempo).

The piece is a study demonstrating a few of the various rhythmic textures the program is capable of composing. At times the composed rhythms delineate a beat very clearly, and at other times they avoid those indicators which traditionally give a listener a sense of beat.

You can hear a brief excerpt of Degueudoudeloupe in MP3 format.

There's Just One Thing You Need To Know was written for pianist Daniel Koppelman. The piece is composed as a "mini-concerto" for piano, which is accompanied by a Korg Wavestation A/D synthesizer controlled by Max software interacting automatically with the performer in real time. The conceptual and musical theme of the piece is "reflection". The music composed for the pianist requires -- almost without exception -- symmetrical hand movement; one hand mirrors precisely the position of the other hand, albeit often with some delay or other rhythmic modification. Even the music played by the computer is at any given moment symmetrical around a given pitch axis. The human and computer performers also act as "mirror images" or "alter egos", playing inverted versions of the other's musical material, playing interlocking piano passages in which they share a single musical gesture, and reinforcing ideas presented by the other.

The computer plays three different roles in the piece. In one role, it is a quasi-intelligent accompanist, providing instantaneous synthesizer response to the notes played by the pianist. In a second role, the computer acts as an extension of the pianist's body-an extra pair of virtual hands-playing the piano at the same time as the pianist, making it possible for the piano to do more than a single pianist could achieve. In a third role, the computer is an improviser, answering the pianist's notes with musical ideas of its own composed on the spot in response to its perceptions of the pianist's music.

The title comes from a statement made by composer Morton Feldman. "There's just one thing you need to know to write music for piano. You've got a left hand, and you've got a right hand. [gleefully] That's 'counterpoint'!"

You can hear a brief excerpt of There's Just One Thing You Need To Know in MP3 format.