Live Program Notes Presented at the Concert

Very little is written or understood about the ideas behind Bohor, and even Xenakis claims to have forgotten how the piece was created in 1962. For the first time, Xenakis's publisher has kindly made available the composer's own sketches for the work and these formed the basis for the following attempt to clarify the ideas underlying Bohor.

Found among the sketches were these hand-drawn contours (image 1, at right). Each corresponds to one of the four sound sources used to create Bohor, as indicated by Xenakis in shorthand toward the left margin of this slide: a Laotian mouth organ, prepared piano, Iraqi and Hindu jewelry, and Byzantine chant. These diverse sources were transformed and assembled into a seamless sound continuum, anchored by a heavy drone derived from the Byzantine chant and Laotian mouth organ, and clothed by percussive sound patterns derived from the prepared piano and bell-trimmed jewelry.

Since no score exists for Bohor, this sketch worked as a guide for analyzing the work. It traces the evolution of the 4 distinct layers, but due to the unconventional nature of this musical notation, it was not clear how they should be interpreted. After running Bohor through a computerized pitch and amplitude tracking algorithm, it was found that the first four contours represented the amplitude for each source, while the bottom graph represented the composite course of pitch for each track. More information about this analysis is available at the online site for this event.

Though Xenakis strives foremost to arouse the imagination of his listeners, the composer has likened Bohor to the experience of listening to a large bell from its interior. Xenakis expressly stated that Bohor "needs space" in order to be heard properly and made careful speaker designations(image 2) for each realization of Bohor, taking into consideration the dimensions and acoustics of its various performance spaces. Tonight's performance follows a projection plan in which each of the 4 sources are fed through a pair of speakers diametrically set apart, creating a circular configuration of 8 speakers enveloping the audience, as shown here, a design that Low Library accommodates nicely. Molding a unique amalgam of sounds in this habitat, Xenakis creates an atmosphere that seems both profoundly sacred and industrial at the same time.

A video was created to accompany tonight's performance, based on Xenakis's pitch and amplitude sketches shown earlier (image 3). Four video tracks in different hues were derived from the 4 distinct audio tracks, so as to create a visual representation of what is heard. The video tracks were mixed according to the same intensities as the audio tracks, while the waveforms of the sound were used to create all visual elements. In order to create a visual continuum, the waveforms were transformed and overlaid on top of each other by a predefined library of mathematical transformations. The form of these transformations is the only artistic license taken in the production, however a connoisseur of Xenakis's work will recognize the ideas of polytopes in the relations between the lines. This polytope (image 4) served as the inspiration for the Phillips Pavilion, where the first piece on the program, Poème Électronique, was premiered.You will also see Xenakis's score sketch, as well as others, displayed on top of the video tracks, not only to serve as a reference for the audience but also to illustrate the stunning resemblance between the macrostructure of Bohor and its constituent microstructures, as shown by the transforming waveforms.

Bohor was called a "huge firecracker," by one of its early critics on account of its remarkable surges of volume. The 23-minute journey through Bohor might be said to be a gradual progress from sound to noise--the last 5 minutes feature an increasing distortion of sound until it steals away into an abrupt silence. While Bohor's magnificent clamor, which contracts and flails about at hefty volumes, may yield an all-too-vivid metaphor of bells ringing in our ears (even after we go home tonight), Bohor is a landmark work, for it invites the audience into the interior of sound, into a realm of close-range listening to which we are not often privy.