Artemis MoroniIA/CTI
Jônatas ManzolliNICS/UNICAMP
Fernando Von ZubenFEEC/UNICAMPRicardo GudwinFEEC/UNICAMP
An Evolutionary Approach
Applied to Algorithmic Composition
http:/ /www.ia.cti.br/~artemis/voxpopuli
BRAZIL
VOX POPULI is WINNER of
The International Competition Dream Centenary Computer Graphics
in Aizu, Japan
http://www.ia.cti.br/~artemis/voxpopuli
VOX POPULI, what is it ?
Ø an end-user interface that allows real time parametric control of sound events;
Ø an interactive environment in which Evolutionary Computation is applied to AlgorithmicComposition;
Ø uses genetic algorithms to generate and evolve a sequence of chords played as MIDIdata.
In VOX POPULI…
Individuals of the population are defined as groups of four voices.
These voices are randomly generated on the interval [0…127], which corresponds to MIDI events:
pitch is represented by the MIDI note table;
duration depends on the rhythmic genetic cycle;
loudness is related to MIDI velocity table;
timbre is given by the General MIDI instrument definition.
Ø In each generation, 30 chords are produced and evaluated;
Ø They are internally represented as a chromosome with 28bits, composed of 4 words with 7 bits:
1010111 1100110 1100111 1110001
http://www.ia.cti.br/~artemis/voxpopuli
Rhythmic Genetic Cycle
REPRODUCTION
CROSSOVER
MUTATION
FITNESS1010101 1011101 0000101 11101011011111 0001101 1101101 00001011010001 0111101 1100111 0101101
1011111 0001101 1101101 0000101Current best chord
interface
Voices Range Criterion
Consonance Criterion
Co(N1, N2) = Intersection(N1, N2)
Musical Fitness
•Octave FitnessO = Max(Oc(xi ))/4, i = 1, 4;
•Melodic FitnessM(N1, N2, N3, N4) = Max[CId(Nj)],j = 1, 4;
whereCId(Nj) = Co(Nj, Id).
•Harmonic FitnessMax(Co(N1, N2), Co(N2, N3,), Co(N3, N4), Co(N4,
N1)
Musical Fitness
F(O, M, H) = Octave Fitness +
Melodic Fitness + Harmonic Fitness
Interface and Parameter Control
Melodic ControlOctave Control
Biological ControlRhythmic ControlOrchestra Control
Interactive Pad Control Red Curve
Melodic ControlOctave Control
Blue CurveBiological ControlRhythmic Control
Fitness Displays
• Notes fitness, on the top;• In the middle, a bar graph shows the four voices
(bass, tenor, contralto, soprano) and their value• The last shows the melodic, harmonic and octave
fitness plot.
Sound Examples
We would like to thank our fellow student Leonardo
N. S. Pereira for developing the
routines to evaluate the consonance criterion. This
work was supported by FAPESP (São Paulo State
Research Foundation, process no. 95/08479-3),
CTI (Technological Center for Informatics), and CNPq (process no. 300910/96-7).