Chance and selection

Melodies seek their way

In JCself a melody is not fixed in advance. Notes arise one after another and influence which notes become more likely later on. In this way musical lines can form, change and disappear again.

So the composer does not prescribe every note, but sets the conditions under which the music develops. The same settings produce a different piece every time.

Try it

This small browser version shows how JCself calculates. Blue is the current value, red the most frequent so far, green the start frequency. The red line at the top shows the distance between the current and the most frequent value. From it the browser version derives note length, loudness and stereo position – a simplified form of what the program does.

How JCself decides

JCself divides the range into narrow regions. Each region has a weight, zero at first. In every run JCself draws a number of random candidate notes, the population, and rates them by the weight of their region, reduced by a random share. From the best candidates, the selection size, it picks one. This note strengthens its region and, a little less, its neighbours.

The more often a region has been chosen, the more likely it is to be chosen again. The distribution of probabilities therefore only arises while the program runs. In the course of this self-organisation, synergetic structures form: one region prevails and becomes the peak of the distribution, others grow and take its place.

The composer only sets the conditions: range, note lengths, tuning system, the strength of chance and selection, dynamics, voices and sound. After that JCself composes on its own, and differently every time.

From weight to note

Every chosen value is a pitch in hertz. The other properties of the note result from its weight and its position relative to the peak:

• Duration and loudness develop from the interplay of the regions of notes: neighbours support each other, distant ones slow each other down, sounding makes tired, rest restores. Alternatively they follow the weight directly – the more often a note has been chosen, the shorter and louder it sounds.
• Stereo position: if the note lies above the peak, it sounds on the right, below it on the left; at the peak it stands in the centre.
• Voices: at the peak – and at the farthest edge of the range – the most voices can surround a note, at half the distance the fewest.
• Chord: justly tuned chord notes form by themselves. At rest these are octave, fifth and third, with rising tension sixths, at high tension sevenths, the tritone and the major second.

When the main voice reaches a peak for the first time, JCself can react: with a sequence of notes in equal steps, the repetition of a motif or a transposition. An additional melody voice changes its note at these points. In the duet and the trio, several such fields stimulate each other with their peaks.

The piece also shapes its own form: the regions that are played fade away, and it dies down when nothing grows back. On its own excitation it tips between dense and relaxed phases, after every phrase it takes a breath, and a listener who knows nothing but this piece listens along – his surprise and his boredom steer the phases, his ear expects a line to go on, and he recognises a motif that returns. If you wish, you draw an excitation landscape or enter a text whose sentences set the course with their prosody – length, stress, breath; the notes are still chosen by JCself itself. All of this is in the tab “Form” of the manual.

The display

While JCself composes, it shows the weight distribution over the range at the top of the window. It is normalised: the highest value always reaches the full height.

Area

the weight distribution.

Line with triangle

the note just chosen.

Ochre dot

the peak, the point of the highest weight.

Open triangle

the start frequency.

While listening, the display runs along and shows the sounding notes and chords. Alternatively, a three-dimensional view staggers the distributions of the last runs one behind the other.

What JCself produces

JCself writes every piece as a Csound file: a single file with instruments and score for the sound synthesis program Csound, which can be edited further. You can listen directly in the program – with Java’s MIDI sounds, with Csound (sounds built specially, the sound from the composition itself, and orchestral instruments from the recordings of the VSCO library, which play by the values of the composition), with a recording of your own, such as a gong, or with external instruments like SWAM and VSCO. The result can be saved as a Csound, MIDI or WAV file and as sheet music (MusicXML).

All settings and what they do are described in the manual.