Elementary Sources

 Elementary Sources by Spencer Topel

Music Score (right click, select, "Save Link As..." to download)

Elementary Sources (2011) examines spectral decomposition as a means of extracting timbral components contributing to the identity of an original source. The movement discussed here was written using a two minute audio recording of brass bell-halves.

A central idea in Elementary Sources was to acoustically synthesize a specific audio sample, like the bell-halves, with an entirely different set of sources, such as a string quartet. This is similar to Gerard Grisey’s ideas for his landmark work Partiels, where he describes the concept of using the orchestra for the purpose of Macro-synthesis, where each instrument of the orchestra contributes specific time and frequency behaviors that culminate in an overall synthesis of a spectral profile, rather than distinctive sections and instrumental motives.

Notation example from Grisey's "Partiels".

Two methods were explored to determine how best to have the four acoustic instruments perform the different extracted components. Firstly, a music notation relating to each distinctive component was devised to best articulate the time-frequency(shown below), similar to Grisey's notation (shown right), but with a magnitude-only representation, (i.e. positive values only to indicate changes in dynamics).  Secondly, audio samples were provided for the performers to audition the sounds for themselves to best determine the execution of these components.

With basic elements of the bell-halves translated to the quartet, it was possible to use a combination of live- electronics (e.g. pitch-shifting, reverberation, compression), and re-synthesized component sample playback to achieve a fairly close relationship between the sampled sources and the acoustic instruments. The result was to create an interstitial space between bell samples and their transcriptions, where relationships in the compositional materials were a subsequent outgrowth of the timbres from the original bell-halve sources.The work as a whole is an hommage to Jean-Claude Risset, and his brilliant bell-synthesis model.

Instrumental Writing: 

An earlier work, "Three preludes for Violin and Cello" inspired the string techniques in Elementary Sources. Particularly the use of irregular bowing, and carefully directed glissandi in the first prelude, (below). Further integration of extended techniques in Elementary Sources included combining glissandi with erratic tremolo, strumming, and harmonic glissandi. 

  Prelude No. 1 by Spencer Topel

First Prelude Score


S.S. and M.A. Casey. Elementary sources: Latent component analysis for music composition. In Proceedings of the International Society for Music Information Reitreval (ISMIR), Miami, USA, 2011.

Source Material can be heard here. Recorded by Case Hathaway-Zapeda on 12.04.10. 

D.P. Casal and M. Casey. Decomposing autumn: A component-wise recomposition. In ICMC, 2010.