THE ELECTRONIC WORKS OF GYÖRGY LIGETI AND THEIR ...

discrepancies here. There is 1 step where the difference between units is 4, 1 step where
the difference is 3. The next two groups are then reversed–there are 3 units where the
difference is 2, and 2 units where the difference is 1.5. Then Ligeti skips the number 5,
and proceeds with 8 units where the difference is 1. This kind of modified additive series
also occurs in later sections, such as Section B, as well, and helps create a feeling of
growth in the short and long range rhythmic design of the piece.
Section A.
Section A (0-40") presents a clear trajectory in which material steadily increases,
first in density and then in register. The material for this section is entirely 20 Hz filtered
noise, and thus recognizable points within Section A are achieved by changes in density
and register, and also by the direction of glissandi. I will divide this section into three
events, the first from 0" to 12", the second from 12" to 30", and the final event from 30 to
40". These are shown below in Figure 2.3.
Event 1 employs upward-moving glissandi and establishes regular pacing. Bands
of 20 Hz noise are grouped in spectra with approximately 9 bands, which extend from
around 50 Hz upwards to around 1200 Hz, where they are filtered out with a low-pass
filter. These bands enter at 0, 6 and 9 seconds and again at 12" with the beginning of
Event 2, establishing units with a common base of 3 seconds.
This pacing also creates the impression of certain bands in the second group being
the continuation of lower bands in the first, an effect Ligeti describes as a “permanent
wave” in his sketches. In fact it is likely that some of these glissandi may have been
43