The musical materials play a central role in The Angel of Death in that they occupy a crucial perceptual and cognitive function in relation to the form of the piece, and were the subject of a great deal of conceptual effort on the part of the composer in defining and refining their nature and their distinctiveness. Given that they were conceived, composed, and recorded early in the whole timeline of the project, there was the opportunity to explore them experimentally and analytically while the full piece was yet to be composed. The recording of these central components of the work early in the project was of course necessitated artistically by their use as the basis for the computer component: edited, they became the sonic source materials that were subsequently processed by the computer to obtain the ten computer images that comprise the electroacoustic layer.
The Composition Stream has described the palette of resources that were predetermined in terms of pitches, number series, and proportions that then shaped the thematic materials. Reynolds described the 18-note disjunct pitch row that was then elaborated into a 56-note conjunct pitch sequence, both being used in various transpositions. He also described the multiple roles of numbers as norms and consistencies that underlay the evolving sense for a listener of what is probable within the universe of a given piece. For, of course, this sense of the probable will be necessary in order to grasp and be affected by what is occurring in the piece. Log series are used as proportions, a feature of Reynolds' music that the Analysis Stream examined and determined to be a unique and crucial part of his temporal and textural aesthetic.
The five thematic textures were conceived in graphic and verbal terms and are associated with specific resources to create separate thematic identities that are crucial from a perceptual standpoint. This perceptual dependency exists because the thematic materials are the sources of everything else in the piece. The textures themselves are therefore conceived to have a specific identity globally. There is also a range of variability within each one, since each is conceived as a complete musical entity in and of itself. As demonstrated in the Perception Stream, a strong rhetorical structure, in interaction with the perceptual properties of its musical surface, gives rise to a unity across the musical variability within each theme. More abstract judgments concerning the belongingness of theme subsections and their temporal orientation depend on factors such as surface similarities and having previously heard the full theme, respectively.
The Composition and Analysis Streams discussed how the themes were each conceived to some degree in pianistic terms, drawing from a history of pianistic gestures, but also how they had to be translatable into their parallel orchestral versions. All of the thematic materials had to be composed for both instrumentations due to the bipartite conception of the form of the piece. Balancing between self-similarity within a theme and the need for enough variation over its constituent subsections to make it musically compelling created a range of perceptual possibilities in terms of similarity relations within and across themes. The Perception Stream has shown how such relations depend primarily on musical surface features such as melodic and rhythmic texture, articulation, gestural properties, and timbre. Timbre plays a particularly prominent role when one examines differences in the network of similarities among theme subsections across piano and orchestral versions. In addition to basic perceptual properties, similarity relations were also rated on the basis of the mood evoked by the thematic subsections, particularly in the case of the orchestral versions. The similarity relations create interesting possibilities for ambiguity of thematic identity, but the analysis based on the perceptual data demonstrates that the composer avoided such potential pitfalls when juxtaposing thematic materials in the derived (Transition and Combination) regions of the piece.
From this point, you may again choose to follow any one of the streams: Composition, Perception or Analysis. The Composition Stream will now elaborate how the thematic materials were developed in the Sectional part of the work and how they were used as source materials for the computer component of the piece. The Perception Stream will study the effect of instrumentation change (between piano and orchestra) on the recognition of thematic materials. The contemporary materials from The Angel of Death will also be compared with tonal materials from a symphonic poem by Liszt. This stream will then explore possible interactions in memory between original thematic materials and their computer transformations. The Analysis Stream will parallel the other two streams by examining the derived instrumental materials as they occur outside of the thematic areas themselves, as well as the role played by the computer component in the work.