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”Volcano Brass - Shock and Awe”

Title Volcano Brass - Shock and Awe
ComposerF.G.J. Absil
Instrum.Studio Orchestra (Brass, string bass and percussion)
Date2011 (orchestral score: 2014)
StyleFilm Music
KeyAtonal (Pitch-Class Sets)
Tempo120 BPM


A musical score excerpt
  • Horns in F 1-2-3-4;
  • Trombones 1-2-3, Bass Tuba, Contrabass;
  • Timpani, Bass Drum.


This short cue is part of the collection Preludes for a Well-Tempered Nature, produced for the Semaine du Son, Brussels, January 2011 event. The score was created afterwards, to illustrate the compositional process with atonal pitch-class (PC) sets.

The mood of the pieces is thrilling, suspenseful and supports the natural sounds, recorded at the Hekla (Iceland) and Kelauea (Hawaii) volcanos. The instrumentation is for brass section, supported by timpani and bass drum rolls. The string contrabass is doubling the bass tuba.

The source sets are shown at the end of the score as two sketches. The PC sets are labeled F0(x-xx), where F is the form (O: original, or I: inverted), 0: the root (0-11, C-B), and (x-xx) is the PC set number. See the interactive Pitch-Class Set Analysis tool on the website (under Archive) for more information. Here is the description of the compositional process:

  • The largest 8-pitch set is PC set (8-24), used in 2 transpositions O0(8-24) and O2(8-24). Note that the overlap between these two sets yields a whole-tone scale. This property is already suggested by the Interval Vector: [464743], which shows a maximum of 7 major thirds, 6 major seconds and 3 augmented fourths between pairs of pitches in the set. Aim for such characteristics, when selecting the initial set.
  • We use subsets from this set complex: PC sets (4-20), (4-21), (4-22), (4-24) and (4-26). Why four-part structures? Well the orchestration has a 4-piece horn and low brass section. We look for the transpositions and inversions of these sets with maximum (i.e., they are subsets) and minimum overlap (for zero overlap, they are the complement of the original set). E.g., O0(4-24) is a subset of O0(8-24), whereas O7(4-24) is its complement. Inspect these properties for the other subsets. Decide on when to introduce new subsets with their interval vectors for tension control.
  • Next comes the vertical distribution of the sets, i.e., the instrumentation. There is careful positioning of the resonant (brass!) consonant intervals, i.e., the perfect fourth and fifth and the highly dissonant intervals of the major seventh and the minor ninth (minor second in close position). This is illustrated in the modified sketch.
  • When creating the score, serendipity strikes. I hit a wrong note, but like the total sound, and obviously keep it (this happened in the opening measures 1-4). The mathematical rigidity helps in starting-off the creative process, but the ears will be the final judge.
  • Then there is control of the overall rhythm and tension. Most note attacks are non-coincident, creating a sense of counterpoint. Note how the lead horn part is ascending, while the bass part is meandering and gradually descending. The result is contrary opening motion, contributing to the cue tension as do the dynamics (ending in fortissimo). Check the voice leading for each individual part; this is particularly important if the cue has to be played by real musicians.

Find the mp3 demo under the menu Audio and look for the title 'Shock and Awe'.