It would take a two-hundred-page book to analyze the whole thing, but maybe I can do the first five and a half minutes (the first section) of the first movement. I have a tendency to be long-winded, but I’ll try and keep it brief (I doubt it).
Looking at the “big picture” form of this opening section, I would personally analyze this as a straightforward additive process, or additive form. If you don’t know what that is, I can try and explain.
Additive forms are usually associated in the modern era with composers of the Stravinskian style, although I don’t think Stravinsky did it that often. And I am not aware of any 12-tone composers using it. In the Contemporary Era it is used quite often in Minimalism as it works extremely well in that style. Jazz/funk and even pop music uses it too.
Anyway, there are two kinds of it. Horizontal/linear, and vertical/contrapuntal. This is what it is. The linear version takes a phrase in a single voice and then repeats it. After it repeats, it adds a new phrase. Then those two phrases repeat one after the other again, in the same order. Then a third phrase appears after that. Then all three repeat (keeping the same order) and the pattern continues: A, AB, ABC, ABCD, or if it were song lyrics it would be:
My name is John….then: My name is John. I like music…then: My name is John. I like music. I am a composer….and so on.
The vertical/contrapuntal version is when there are multiple voices, but they don’t do the horizontal thing above, what happens is this:
Voice 1 plays say, an 8 bar phrase. A.
Voice 1 repeats the same 8-bar phrase A as Voice 2 enters an 8-bar phrase B.
Then Voices 1 and 2 repeat their same phrases assigned to them A and B respectively while Voice 3 comes in with 8-bar phrase C.
And the pattern continues.
A……..A……..A……..
B……..B……..
C……..
The illustration for this would be the Jazz-rock standard Chameleon by Herbie Hancock as covered by a lot of bands. What you’ll often hear is the signature bass line start, then it repeats, but on the repeat, the drums enter, and then those two instruments repeat, but when they repeat, the guitar/keyboard comps the chords, those three repeat their parts together, but then the next time around the cycle, the melody comes in. Sometimes, you’ll hear it do the opposite on the outro. The instruments drop out on all the repeats one at a time until the bass is left on the last repeat.
Three points to keep in mind: this is not a fugue as the parts do not interchange with each other, and also each part must repeat over and over in its own voice (this is not free counterpoint, or a free layering of parts). And when a voice enters, it doesn’t stop and the line doesn’t carry somewhere else. An additive process is a unique thing.
Children’s songs usually use the horizontal version while everyone else, including classical music, usually use the contrapuntal kind. Schnittke is no exception. The section from the piece in question is a vertical/contrapuntal additive process.
So right at bar 1, the chimes at the beginning would be voice 1 playing material A (I will go into actual note analysis at a later time), then as each new voice enters, you see he marks the score with wavy lines of the voices already entered indicating the previous material from the previous section of that instrument is to be repeating/continued over the new material from the new instrument. Then that new instrument gets a wavy line on the repeat, etc., etc. Its an additive process. Note that each line is repeating its own material when each new voice enters and that no lines share material. Also note that when a voice enters, the line doesn’t stop and carry somewhere else. Hallmarks of additive form.
Notice how this was composed with expert craftmanship, if you don’t mind me saying so and shoehorning in my hobbyhorse. What I mean is this. If the goal was to get to the 5 minute texture, because maybe that what he heard in his ear or had in his head, what would have been an audience reaction if you started at the 4:30 or 5:00 mark? It would sound like noise, and wouldn’t make any sense. It’s a mess.
I love how the audience applauds at the end of this section at the beginning of this movement!!! It’s because of what he did. He made it work. What he did was lead up to and progress to the “chaos” or “cacophony” logically and by a pattern, so that a listener can follow it coherently and make audible sense from it. It was the additive form. Each voice did not change, either orchestration-wise (every instrument kept playing to the end), and it repeated its material as each new layer entered. It’s extremely smooth, patterned, with a sense of predictability, yet there’s excitement in what is going on. He is essentially “spoon-feeding” the audience the music so the complexity at the end seems inevitable.
It's like what I always say about taking principles of the past in order to write competent music today. Such as in counterpoint. Counterpoint is similarly used as above. An audience will generally accept almost any kind of harmony, dissonant or otherwise, any kind of tonality (quartal, pandiatonic, even microtonal), if the counterpoint is logical and crafted well (not referring to style). This is what we have learned from the past (i.e., Chopin and others).