8 : glissandi contraries
There are two types of this last basic sound. The first one consists in playing a double stops and doing a glissando in the opposite direction on each string, ascending on one string, descending on the other (example of the third section). The second one consists to play in double stops one fix note and do the glissando on the other string. In this case, like in the example of the first section, Xenakis counts the battements by second between the frequences of the two notes.
The basic sounds : the Nomos Alpha's sound universe :
The conception of the path A of Nomos Alpha is based on these eight basic sounds. They are the original material of the sound universe of Nomos Alpha. Furthermore, we are going to find again many characteristics of Xenakis language : the glissandi, the notion of clouds of sound or the "granulation" of the sound. Consequently, the basic sounds participate to the piece's coherence. On the other hand, as we have 18 sections in path A, so we're going to hear 18 different versions of these eight basic sounds. All versions in each section are different (different durations and intensities), so the basic sounds participate too in sound renewal during the piece. We're going to develop this aspect of the constant renewal of the sonorities in the part relating to the organization of basic sounds. But now, we will focus our attention on what concretly are the basic sounds.
Firstly, we are going to try to describe, to define each of them. To illustrate this point we are going to compare the two first "versions" of the same basic sounds, in the first section and in the second section. In second time, we're going to do a short comparative analysis between of this "versions". We will attenpt to understand how Xenakis uses this base materials to compose, and why he sometimes makes an exception to the "rule".
7 : Atom represented on a cello by interferences of a quasi-unison
(Or sound sustain with or without battements)
This basic sound is often made of with hold notes: on one note or in double/triple stops, like in the first section. The sound could be smooth or with granulation as in this to first section. In Nomos Alpha the quater-tones are very frequent, notably here used in this triple stops to create the granulation, the interferences.
To create sound masses, the ataxic concept is dear to Xenakis. Indeed, we can be related the ataxic concept to the stochastic music. In this case Xenakis uses probability calculations to conceive the sound. For this basic sound, we have two different versions in the first two sections: in the first one it's a point, one note. In the seconde one, it's a cloud with several notes. In this two examples we can notice that Xenakis uses the pizzicati certainly because it's percussive and illustrate well a point.
3 : Pizzicati on one note
The description of this basic sound seems very clear and simple and the second section is a good illustration, just on note. However, if we examine the first section, we find that Xenakis wrote, not pizzicati, but col legno, and not on a single note but three different notes. There could be several explanations: I think he chooses to use the col legno rather than the pizzicati for artistic reasons. Indeed, this basic sound in the score is just after the number 2 (Pizzicati ascending or descending), so that it could normally be two basic sounds in successive pizzicati. Xenakis, in his search of new sounds, wishes to contrast. In addition, pizzicati and col legno are both percussive playing techniques. As we saw in the first part, Xenakis conducted research on the global perception of sound. Here, he works on the granulation of the sound, as if he wanted to give a material to the sound. In my opinion, that's why he uses three notes, like an improved trill.
6 : Glissandi ascending or descending
Once more, we can observe the importance of the glissandi in Xenakis' language. In the first version, Xenakis works on the speed of the slide.During three first half notes the slide speed is: one quarter tone by half note, and from the fortissimo until the end of the basic sound the slide speed is one semi-ton by half note. If this passage was written on a graph we could see two different slopes. In addition, Xenakis writes dynimics - (mf) crescendo fff descrecendo p-. In theory there is only one dynamic for this basic sound -fff- but here he moves around it.
4 : Ataxic field of sliding sounds (Or sound sustain with granulation or battement)
Here again we'll find the idea of the granulation and the global perception of the sound. Especially in the version of the first section, Xenakis wants to create a cloud of sound and makes a three-dimensial sound with this trill in double stops.
As we have seen, the glissandi are very current in the Xenakis language, especially in a piece composed from a graph. It's the basic sound who starts Nomos Alpha, and the first at the beginning. It's not an ascending or descending pizzicato,but a hold note during one bar and one quarter note, before an ascending line. Staying on just one note is not a mistake, because in Xenakis's mind an holding note is a glissando with a null slope. On graph, this passage would be a horizontal line.
