Computer music

7 Algorithmic improvisations for guitar and/or computer

ICT Improvisation 1 (6 min. 51. Sec.)
The computer starts with an empty memory. As the guitar plays several successive rule bases of the computer are filled with rules derived from the guitar improvisation. In the first part of the piece a flute, an Aah-voice and a xylophone melody develop randomly. In the second half the xylophone has to follow the guitar. Later the restrictions for the xylophone are relieved and the piece develops in to a rich sound-world of random interactions between the instruments.

ICT Improvisation 2 (2 min. 22 sec.)
The piece starts with a background of melodic material learned from improvisations on the theme of a sailor's dance. Against this background the guitar programs a rule base for a slow synthesizer melody.

ICT Improvisation 3 (3 min . 12 sec.)
The working title of piece could be 'Teasing the violin'. A violin is allowed to improvise freely on a Bach grammar, but only as long as the guitar does not play. As soon as the guitar sounds the violin has to conform to the melodic material of the guitar. The result is quite funny. This is an interesting form of algorithmic anti-improvisation made possible by grammar induction techniques.

ICT Improvisation 4 (2 min. 34 sec.)
Rule bases for several percussive instruments are filled with material from very fast dance melodies. These instruments are forced to follow the melodic material of the guitar. The setting of the ICT is such that the original melodies are not reproduced but instead a fast random repetition of notes is generated. In this way the guitar is transformed into a percussive instrument. Under each note a random rhythmic pattern is hidden. I imagine that Conlon Nancarrow (1912-1997) would have loved these new possibilities for improvisation.

ICT Composition 1 (1 min. 20 sec.)
An example of pure algorithmic composition constructed with ICT. The instrument grammars are derived from the first movement of the second Brandenburg Concerto by Bach (1685-1750). The chorus structure of the piece is based on a composition by Orlando di Lasso (1532-1594): Mon coeur se recommande à vous. The combination of the two leads to a completely new piece.

Delay Improvisation 1 (5 min. 43 sec.)
Delay is one of the simplest algorithms that can be applied to the sound of an instrument. Yet the possibilities are almost limitless. In this piece the rithmic possibilities of delay are explored. The guitar is a 1975 Howard Robberts Ibanez stereo guitar with a piezo element and a humbucker. The signal is first transformed by a delay box and then fed in to a male-female voice distortion program.

Sequencer Improvisation 1 (3 min. 39 sec.)
I always like to improvise on a simple drum pattern. A sequencer program generates the drums. The improvisation is done on a Godin Multiac midi guitar fed in to a Roland GR-09 synthesizer with a mix of base guitar sound and the normal acoustic sound of the guitar itself. The mixed signals give a rich percussive sound that blends well with the drum patterns.