[Rediscovered Treasures]

A column by Eldad Tsabary about works from the past that he has recently revisited: an appreciation of both the “classics” and lesser-known works.

Iannis Xenakis — ST/10 (1962)

by Eldad Tsabary

Iannis Xenakis — ST/10 (1962), for 10 instruments
Première: 24 May 1962, IBM-France Headquarters, by the Ensemble de musique contemporaine de Paris.

Like Metastasis in the last column, my Rediscovered Treasure this time around is a stochastic piece by Iannis Xenakis.

Similar to Metastasis, this piece is crafted from a combination of individual glissandi and many individual sonic events. It is one of seven pieces Xenakis composed in 1962, including ST/48 — 1,240162 for 48 instruments and ST/4 — 1 ,080262 for string quartet, using his stochastic music computer program ST, which he developed 1956–62 on an IBM 7090 computer. All seven pieces used identical concepts and processes and I select ST/10 out of a personal preference and because it is available for listening in a flac format on AGP (see below). Similarly to the program used by Lejaren Hiller in creating the Illiac Suite (1957), ST/10 provides textual data that needs to be transcribed to musical notation by the composer, who is required to make a variety of compositional choices. However, ST/10 controls a much larger number of parameters than Hiller’s Illiac program, including pitch, duration, instrumentation, instrumental technique, dynamics, glissandi, and more. The defining stochastic aspect of all ST pieces is their structural organization into sections — or movements — of different average densities. In other words, the probability distribution of the sonic events is the main subject of an ST piece, and all the stochastic choices made by the computer are related to it. The naming convention Xenakis chose for these pieces is descriptive of the features of each ST composition: For instance, in ST/10 — 1,080262 “ST” stands for Stochastic, the number 10 for ten instruments, the number 1 for version one, and “080262” is the date of data generation by the computer, in this case 8 February 1962. This piece is constructed with three dense sections, separated by two sparse ones. The sections‚ average densities computed by ST are between 0.11 and 50 sonic events (note onsets) per second. The stochastic process allows for variation in each section’s density as long as the mean is maintained. Though the construction of the overall structure from individual events is non-linear by nature, the glissandi and long tremolo notes provide the temporal glue that holds all the pieces together.

Listen to it on the Avant Garde Project website.