I will assume in this text that the reader is already familiar with the possibilities and characteristics of the Ligeti Hall (see On Research/The Lab) as well as with the underlying project ideas.

The whole Topoi setup comprises twenty-four from the thirty-three hemi-speakers at the Ligeti Hall, nine flying speakers on stands and two large sub-woofers on the floor, plus six from the eight sky-subwoofers on the ceiling, the whole sky-top (thirty-six) and another four sky-wall speakers. Not all of the sky-top speakers are used in one single performance, but they can be used, since the mapping of output speakers follows an algorithmic choice in some sections.

The process of constructing and polishing this setup has accompanied and, we could say, has been part of the composition of the piece. The initial idea, as already stated, was that of having different, well-defined, "places" where several sound-objects could dwell and flow.

The first three figures, beyond the initial picture, used here as portico to this entry, show the setup from different perspectives (front-right, back and back-left).

1. I was naturally basing myself as first approach on my previous experiences with "triangles" of speakers and in this case I was searching for a double constellation of three hemi-speakers. These constellations should be distant enough in space to discriminate easily between them, though not too distant to permit communication, and also be as similar as possible. Each one of them, on the other hand, was to be ample enough but not exceedingly so. Let me remind, at this point, that the position of the hemi-speakers is fixed in the hall.

Figure 04 shows the best configuration I could discover. As you see the size of the triangles is almost identical, and the distance between the two groups allows to separate them perceptually in the Hall. The triangles have a side length of around 4 meters, and the distance between the centre’s of the triangles is about 8 meters.

To this first double-triangle I added a second double triangle, this time with sky-top speakers, almost on top of the previous. Figure 05 shows a double perspective of this configuration.

With this set of twelve speakers I could already experiment with the idea of building bodies delimited by surfaces, and, very important, to work with the combination of several coexisting sound-entities. As you may deduce from the figure, the three lower speakers are oriented to the inside of the triangle. This first setup enabled me to compose a short test-study. The result was promising, though the different qualities of the lower and higher "surfaces", and the fact that the sky-top triangles were pointing downwards, implied some difficulties.

2. The next step was taken some time after, and included adding another double set of three speakers. This time I was using speakers of the same type as the hemi's, and placing them on stands on the floor at precisely defined positions. This is shown in Figure 06. This new configuration was much more powerful, controllable and implied a much larger vertical breadth while still assuring energy enough all along its height. I think it was at this time, that these speaker-structures got the nickname of trees, and the evolving study-case became familiarly known as the Two-tree (later Three-tree) piece.

3. The idea of enhancing the boundaries between these two first structures, but also of favouring potential links and movements, of extending the possibilities through combinations of different type of sound-entities, led to the idea of a next intermediate surface, different and similar, by using four more hemi-speakers as in Figure 07. This very interesting new element, developed naturally further complementary extensions. First by adding a lower surface, as seen in Figure 08, with three more flying speakers, of the same type as the hemi's, on the floor. Later a higher surface, Figure 09, this time composed of four sky-top speakers reinforced with one central hemi-speaker looking upwards to add further consistency to the higher surface. As you see in this last figure, the nomenclature of the tree structures follows historical rather than geographical reasons.

This complex structure has proved to be a rich potential basis for research and for the composition of music with the types of sound-structures I wanted to work with. The exact design of heights, tilts, orientations and, wherever applicable, positions, has been a long process, searching to avoid certain reflections, looking for coherence and also to potentiate and enhance the multi-functionalities that each sub-structure would have to fulfill, evolving with the musical ideas. Figure 10 shows the exact heights and tilts at the final setup. Figure 11 (Tree 1), Figure 12 (Tree 2) and Figures 13 & 14 (Tree 3) show pictures of these structures in the Hall. It is really difficult to photograph the speakers in the Ligeti Hall, so in order to give some impression of their relative positions and orientations, at the time of taking the pictures I had to slightly lowered down the hemi-speakers, while keeping tilt and orientation.

4. Bound by the fixed positions of the hemi-structure, the 'Three-Tree' setup is imposing a diagonal direction across the hall. I decided to underline this characteristic, first by positioning the floor large subwoofers following this diagonal (though the reason for this was more visual than aural), and later on by adding two more structures of speakers at the corners of the Hall, as shown in Figure 15. This extension, about which I will briefly talk later on, was followed by another symmetrical dual set of hemi-speakers at the sides of the Hall, as shown in Figure 16.

5. The first extension I just mentioned, the two sets of speakers at the corners are composed of a mixture of hemi, sky speakers and sky subwoofers. In Figure 17 I have isolated these double structure and added the lower third Tree, which serves as a transitional 'place". With this setup I could play with the idea of a pendulum across the Hall, which can be listened to at minute 07' 00" in the piece. It is impossible to photograph with any clarity this structure.

6. The second extension, the dual symmetrical structure at the sides of the Hall as represented in Figure 18,  has had its own research path. You may see in Figure 19 a picture of one of these structures, and as you may observe the idea was to attempt through the orientation of the different speakers to create an "internal" surface close to the wall, something like a "thin" film of sound in the space defined by the entire Hall. My nickname for these configuration was the Rosaces (Rose-windows), and arises from the idea of designing patterns of movement and colours varying in their "inside". Much caution had to be taken with the unavoidable reflections that this setup was producing. The orientations at this height depicted in the picture,  force first reflections to be rather neutralized. This was a really interesting experience, working with different sound-structures, different qualities, different spatial behaviours.

Again, the possibility of having sound-objects move between the two of them, led finally to different configurations, as shown in Figures 20 & 21, were, either Tree Three or Trees One and Two would serve as linking bridge-places between the two Rosaces.

7. This whole setup of speakers was complemented with the sky-top speakers, addressed in different ad-hoc constellations. Figure 22, shows the whole structure of speakers (with only a choice of top-speakers for comprehensibility).

It might be interesting to observe that until a certain moment there was never a thought about an audience coming to listen to the music with this setup. The whole design process had been evolving following exclusively the needs of research and composition. Guests had obviously passed by and listened to preliminary studies and even to the whole piece or to excerpts of it, but sitting down even a small audience had not been a consideration. The setup, or I should rather say the music composed with it, makes full sense when listening to it from the 'outside' : the (thick-)plane formed by the diagonal Tree structure being external to the auditor. Indeed the listener will always be inside, because there are many speakers-structures used along the piece, but they should certainly not be place in the diagonal of the Hall. Figure 23 shows a picture of one of the seat-plans, this one designed for the first public concert. After that first experience, I was able to design other, more extended seat-plans, but never really large.

This is probaly one of the most unpractical pieces of music ever done. It can only be listened to at the Ligeti Hall of the Mumuth, and only by a few people at a time.

One important thread of tests and experiments along the project has been concerned precisely with the idea of a choreography of sound objects. Designing strategies of placements and displacements; polyphonies of bodies –sound entities with different qualities– performing spatial movements across the network of places that the setup was providing.

From this perspective the need of a corporeal (bodily) perception is paramount, and therefore, this line of research was greedy of developments in the search for the plastic sound object, becoming an important active demander of perceptual qualities and functionalities.

Tests with one ‘body’ were important in order to work out and polish the perception of placement and the smoothness of inter-place movement. Almost every different quality, and each different type of movement requires a special particular attention, as it were, a different strategy. And then, of course, as music knows well enough, one thing is to deal with one voice, one object, and quite another one to deal with a polyphony of objects. Qualities that mask others, gestures, spatial or otherwise, that get intensified or diminished because of other ‘parallel’ behaviours.

I built several short studies with such a scenario, some were dull and very study-like, others were really curious and in some case even providing some humorous aspect. Although the spirit of movement in space is present all along the piece in one way or other, I was searching for a special moment where the idea of a coreography would be particularly in the foreground. Nothing seemed to fit, however, into what I felt that the Topoi discourse was requiring. Like so many other times when confronting a problem, there is a struggle to find a solution, apparently getting defeated until one day out bursts the idea apparently coming from nowhere.

A spatial counterpoint, a spatial double canon in four ‘voices’. A discourse built of musical gestures incorporating a spatial behaviour in its essence. Starting at 09 minutes 59 seconds, in section IV, the four main qualities perform a contrapuntal dance across the six-place space defined by the ‘3-Tree structure’. Figure 01 shows this spatial universe with its six possible places.

Once the essential idea was clear, the process of composition of this part of the piece became indeed an interesting pursuit. Building the music for a choreography or the choreography for the music; sonic matter to listen to, but to be perceived through its movement in space at the same time. The relationships between the movements of different ‘bodies’, the relationships between different ‘voices’. The idea of a canon, of counterpoint, and its very special requirements. Articulation in time, essential for the canon and fundamental for the perception of sound in space.

It might not be uninteresting to comment that I had to ‘invent’ several different representations, in order to build and control the development of the whole. One of these auxiliar representational tools was a sort of tachygraphic notation of the spatial gestures, thanks to which I could express in a simpler way the moulds (the canon subjects) and all further ‘transpositions’ and variations.

Even if essentially performing a same structured gesture, every different object requires particular polishing details in its design in order to bring forth the idea. The syntax of the software-score to handle this type of spatial objects is, on the other hand, very powerful but bulky and relatively complex, since there is only a simple hierarchy of representation in its spatial notation, so a compact representation, a simple syntax hiding all special nuances –essential but ‘secondary’–, allowed to write a software score which was more legible and hence easier to manipulate and retouch. The mandatory individual treatment for each of the different sound-objects, the needed adaptation and adjustment for each one of them and the ‘surface’ refinements added to each sound gesture being worked out later as another layer in the working process.

An altogether different representation was a graphic one, as shown in Figures 02 & 03. This representation allowed me to visualize the spatial distribution and, as I humorously put it, helped me to avoid ‘parallel trees’. Rather than the awkward final result, it was the process of building these sketchy representations, of which I did many, what helped me to have an overall idea of spatial-movement relationships and global energy distribution.

Figures 04 to 08, show an schematic drawing of the spatial movements conforming the first ‘subject’. Figures 09 to 12, show that of the second ‘subject’. These figures have not been part of the auxiliar representations with which I worked during the composition, they have been done expressely for this documentation, as a useful representation to transmit more clearly the global idea by helping to visualize the elements of which the ‘subjects’ are composed.

The first of these elements, Figure 04, is a simple gesture which remains in one place. It does so through an arch gesture of opening and folding back, turning slightly, rising and descending, with a dynamics and colour inflection contour following a parallel strategy. It is sound in space conceived as one gesture as a whole.

The second element, Figure 05, describes a movement upwards. This is a subtle movement, because we remain on a same vertical. To underline the movement the sound object marks clearly its position on the lower ‘place’ before going up and exploring partially the higher ‘place’. It is rather delicate to explore the higher ‘places’, as a contrast to the lower ones, because the top-most speakers (sky speakers) are very different from all the rest of the speakers. Solely through the sky-speakers the sound quality would be differently coloured, and this affects more some qualities than others, as it is natural. So one has to deal with all these different aspects when constructing the flow.

Movements across ‘Trees’ are most dramatically clear, vertical movements are subtle and include almost always the perception of an internal temporal articulation, as a slur, so to speak. Some of the sound objects are more agile, and their movements can be faster and crisper, while others define better the places they dwell in, but their movements are stately as if imbued of a weighty essence.

Colour, weight, matter, bodies, movements in space. And yet, counterpoint, canon, sound.