Computer-generated music
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Computer-generated music is music composed by, or with the extensive aid of, a computer. Although any music which uses computers in its composition or realisation is computer-generated to some extent, the use of computers is now so widespread (in the editing of pop songs, for instance) that the phrase computer-generated music is generally used to mean a kind of music which could not have been created without the use of computers.
We can distinguish two groups of computer-generated music: music in which a computer generated the score, which could be performed by humans, and music which is both composed and performed by computers.
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Computer-generated Scores for Performance by Human Players
Many systems for generating musical scores actually existed well before the time of computers. One of these was Mozart’s Musikalisches Würfelspiel, a system which used throws of the dice to randomly select measures from a large collection of small phrases. When patched together, these phrases combined to create musical pieces which could be performed by human players. Although these works were not actually composed with a computer in the modern sense, Mozart uses, though in rudimentary form, the same algorithmic techniques that composers now often use with the electronic binary digital computers in existence since the Second World War.
One of the first composers to write music with a computer was Iannis Xenakis. He wrote programs in the FORTRAN language which would automatically produce scores to be played by traditional musical instruments. An example is ST/48 of 1962. Although Xenakis could well have composed this music by hand, the intensity of the calculations needed to transform probabilistic mathematics into musical notation was best left to the number-crunching power of the computer.
Computers have also been used in an attempt to imitate the music of great composers of the past, such as Mozart. A present exponent of this technique is David Cope. He wrote computer programs that analyse works of other composers to produce new works in a similar style. He has used this program to great effect with composers such as Bach and Mozart (his program Experiments in Musical Intelligence is famous for creating "Mozart's 42nd Symphony"), but also on his own pieces, combining his own creations with that of the computer.
Some critics claim that computers are unable to produce music of the same quality as the great composers, though others would ask whether or not this is really the point of producing music in this way.
External links
- Samples of David Cope's music:
- http://www.spectrumpress.com/cope-mp3.html
- Roll over Beethoven (http://www.music.gla.ac.uk/~tfowler/articles/Computer.html)
- Charles Fox's computer cross-breeding of Bach with the Spice Girls: http://www.charlesfox.org.uk
- Marc Fraser - composer of fractal-generated MP3s http://www.soundclick.com/bands/4/marcfrasermusic.htm
Music Composed and Performed by Computers
Later, composers such as Gottfried Michael Koenig had the computers generate the sounds of the composition as well as the score. Koenig originally produced algorithmic composition programs which were similar to Xenakis', in that they translated the calculation of mathematical equations into musical notation which could be performed by human players. His programs Project 1 and Project 2 are examples of this kind of software. Later, he extended the same kind of principles into the realm of synthesis, enabling the computer to produce the sound directly. SSP is an example of a program which performs this kind of function. All of these programs were produced by Koenig at the Institute of Sonology in Utrecht, Holland in the 1970's.
Procedures such as those used by Koenig and Xenakis are still in use today. Since the invention of the MIDI system in the early 80's, for example, some people have worked on programs which map MIDI notes to an algorithm and then can either output sounds or music through the computer's sound card or write an audio file for other programs to play.
Some of these simple programs are based on fractal geometry, and can map midi notes to specific fractals, or fractal equations. Although such programs are widely available and are sometimes seen as clever toys for the non-musician, some professional musicians have given them attention also. The resulting 'music' can be more like noise, or can sound quite familiar and pleasant. As with much algorithmic music, and algorithmic art in general, more depends on the way in which the parameters are mapped to aspects of these equations than on the equations themselves. Thus, for example, the same equation can be made to produce both a lyrical and melodic piece of music in the style of the mid-nineteenth century, and a fantastically dissonant cacophony more reminiscent of the avant-garde music of the 1950's and 1960's.
Other programs can map mathematical formulae and constants to produce sequences of notes. In this manner, an irrational number can give an infinite sequence of notes where each note is a digit in the decimal expression of that number. This sequence can in turn be a composition in itself, or simply the basis for further elaboration.
Operations such as these, and even more elaborate operations can also be performed in computer music programming languages such as Csound, PD and Max/MSP. These programs now easily run on most personal computers, and are often capable of more complex functions than those which would have necessitated the most powerful mainframe computers several decades ago.
Another 'cybernetic' approach to computer composition uses specialized hardware to detect external stimuli which are then mapped by the computer to realize the performance. Examples of this style of computer music can be found in the middle-80's work of David Rokeby (Very Nervous System) where audience/performer motions are 'translated' to MIDI segments. Computer controlled music is also found in the performance pieces by the Canadian composer Udo Kasements (1919-) such as the Marce(ntennia)l Circus C(ag)elebrating Duchamp (1987), a realization of the Marcel Duchamp process piece Music Errata using an electric model train to collect a hopper-car of stones to be deposited on a drum wired to an Analog:Digital converter, mapping the stone impacts to a score display (performed in Toronto by pianist Gordon Monahan during the 1987 Duchamp Centennial), or his installations and performance works (eg Spectrascapes) based on his Geo(sono)scope (1986) 15x4-channel computer-controlled audio mixer. In these latter works, the computer generates sound-scapes from tape-loop sound samples, live shortwave or sine-wave generators.
External Links
- Csound: http://www.csounds.com/
- PD: http://www.puredata.info/
- Max/MSP: http://www.cycling74.com/
- ChucK: http://chuck.cs.princeton.edu/