Why this title ?
In greek Nomos could have several meanings:
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“The rule”, “the law”: this understanding refers to the use of mathematics for the conception of this piece, acting as a rule governing the whole work.
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“Mode” or sometime “special melody”: this aspect is less obvious than the first one. But as we have seen in chapter on the context of the genesis of Nomos Alpha, we know that during the period of the composition, Xenakis had a special interest for the demonic music -the ancient greek music- and more especially for the working of the scale system. Using the sieves theory is for him a method to create many scales -modes- in its own way.
In this preface we find some important notions to understand the piece, that we are going to develop. On one hand the “extra-temporal architecture” and on the other hand two main concepts - “rules”- of Nomos Alpha: the “theory of groups” and “theory of “sieves”".
Nomos Alpha (1965-66), analysis presentation
Source:Fernand Vandenbogaerde,
analysis of Nomos Alpha of I.Xenakis
A-/Initial contact with Nomos Alpha: listen to it!
As we have seen above, the perception of sound and the experience of the listener are very fundamental elements of Xenakis' music Therefore, I invite you to listen to the first part of the piece with the score before talking about the analysis of Nomos Alpha. Recording of Christophe Roy
1 ) The macro-strucure : the Paths
Nomos Alpha is comprised of six parts. We just heard the first of them which is the first line of this table. To compose each part, Xenakis uses two Paths :
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the Path A: the principal one, 6 parts each comprising 3 sections
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the Path B: 6 intermezzi between the Path A sections.
Each path has his own conception. The path A is the first "type of music", energetic and fragmented, composed with micro-events. In this path, all the parameters are formalized and calculated. Whereas the path B is the second type of music, in a more "free" conception. Xenakis usually uses in Path B long notes and explores the extremities of the cello registres.
Now we are going to look at the group theory in the next part: The organisation of the basic sounds: the group theory
To compose the path A, Xenakis uses eight basic sounds and organizes them with the theory of the groups: he uses here the 24 cube-transformations onto himself in the space. The eight basic sounds correspond to the eight apexes of the cube, and each transformation gives to Xenakis an order of appearance different from the basic sounds. In a same way, this process is used to organise the intensities, the durations and densities of the sounds. We will see later how these cube-transformations work. Now, we are going to look on the eight basic sounds.
The eight basic sounds:
The basic sounds are the “atoms” of the piece,sincethey are the ones who give Nomos Alpha his special sonorities and his indentity. We can find more informations about the creation and the transformations of these basic sounds on the page The basic sounds : theNomos Alpha's sound universe. Here is a list of the eight basic sounds with their symbols:
Comments: In this first part, we heard two very contrasting types of music:
- The first: very energetic and fragmented, with a lot of rests between the different sounds, the Path A.
- The second, just at the end: more continue and soft with very long notes, the Path B.
Now let's see how these two "types of music" are organised in the general structure of Nomos Alpha
Path A is constructed as a juxtaposition of micro-events that are in fact the different basic sounds, which produces a very fragmented music. This is accentuated by the presence of a lot of long or short rests between these micro-events. Therefore it's easy to see in the score the delimitation of each of them. You'll find in each section the eight basic sounds in the order given by the cube-transformation. When the eighth is played, a new section from a new cube transformation start.
1 : ataxic cloud of sound-points
2 : Pizzicati ascending or descending
3 : Pizzicati on one note
4 : ataxic field of sliding sounds
(Or sound sustain with granulation or battement)
Comments about the basic sounds organisation:
- the order in the first section is: 2314 6758
- the order in the second section is: 5687 1243
5 : relatively ordered ascending or descending field
of sliding sounds
6 : Glissandi ascendin or descending
7 : Atom represented on a cello by interferences of a quasi-unison
8 : glissandi contraries
Example of Path B. Xenakis combines the two extremities of the cello's registres. On one side, very high with the harmonic sounds, and one the other, with the C string tuned one octave below.
Symbols abstract to : Fernand Vandenbogaerde,
analysis of Nomos Alpha of I.Xenakis2
Table abstract to : Fernand Vandenbogaerde,
analysis of Nomos Alpha of I.Xenakis3