Chance for String Quartet
One day in mid 2024 while considering what was possibly my most original work, I settled on "Three Chance Pieces Plus One" for piano (No. 47). I thought, if I were to extend the ideas of this work, it would be most interesting to use them for a string quartet. I decided to do this using the same "cells" and form which I had used for the piano piece:
The number of notes in each cell and the content of all 6 cells were determined by chance. Then these were transposed to the 12 steps of the chromatic scale.
At first I planned to use the same rhythmic and register patterns I had used for the piano pieces but since I was now able to use a computer instead of a die I could have chance operations with different probabilities (as 1-6). My adaptation of the earlier plan now looked like this:
Register refers to the pitch regions (high, middle, low) of the instruments in pairs: 2 Violins (top) as one pair and Viola and Cello (bottom) as the other. There are 8 register diagrams showing lines in regions high or low or of lines depicting movement from one region to another. The 8 Register diagrams have equal probabilities.
Then there are 8 rhythmic shapes and since 2+3, 4+5, and 6+7 are all equal pairs the three different shapes have a probability of a quarter while 1 and 8 each have a probability of one eighth. However after an early trial I decided to delete rhythmic shape number one and double number eight, so in the end number eight also had a probability of one quarter. The colour scheme corresponding to the Rhythmic shapes is explained below the next diagram.
At this stage I wrote to Rod Harries about the project and he agreed to design me a computer program which would produce a diagram of the complete movement. The text of this program will be published here at a later date.
I wanted the piece to be made of 50 bars of irregular lengths. These would be shown on the diagram as "boxes" and would have durations in seconds using numbers from the Fibonacci series: 1, 2, 3, 5, 8, 13. These "boxes" would occur with different probabilities: durations 1 and 13 would each have probabilities of 0.1 and the durations (2, 3, 5, 8,) of 0.2 each. My wish was to have as much information as possible on this diagram. Rod set aside the left of each "box" for four numbers, plus two numbers in the middle, another above and two beneath. Taking "box" 16 as an example I have labeled these "box"-numbers a, b, c, d, e, f, g, h, i (in red) and described them below. At the top and bottom of the "boxes" are groups of 2 or 3 "coloured blobs", (marked with red square brackets). These are to show how the quavers in this "box" are to be grouped in 2s and 3s.
The colours of these "blobs" are used to show the Rhythmic patterns. Since there are now just 4 different Rhythmic patterns only 4 colours are needed and it is unimportant whether the blobs are "filled or empty".
Black: 8. Red: 2 or 3. Green: 4 or 5. Blue: 6 or 7.
Another important principle is that of a surprise. Since so much of the sound material is quaver movement, the need for a surprise is great. To this end there are two sorts of "contrasting boxes": one marked orange where the quavers are replaced by tremolandi and the other green where we hear loud glissandi.
I let the program run several times and then chose the following diagram to realise in musical notation:
The next job was to transfer all this information onto the score. This "working score" contained 4 extra staves, two for the Pitch Cells (top and bottom pairs of instruments) and two more for Register (also top and bottom pairs) and Rhythmic shapes:
Although so much was determined by the chance system of the computer program there was still much that I could decide myself. The most obvious parameter which has not yet been mentioned is loudness (dynamics). I also allowed myself to include extra rests and occasionally longer notes. Tempo and tempo changes were determined later as was timbre (arco/pizz.).