Percussion and Real Time Computer Sound Transformation
by Lawrence Casserley

This composition will consist of seven movements, which can be arranged into various orders by the performer, following a clear set of criteria. The seven movements will be: "Bellbuoys 1", "Bellbuoys 2", both scored for various bells, "Cyclone", for drum, large metal bars and large woodblocks, "Navigation", for seven varied instruments chosen by the performer, "Foghorns", for bowed cymbals, "Waves", for various shakers, and "Deep", for gong.

"Deep" asks the player to choose sounds on a large gong that best articulate the graphic score, which can be arranged in a number of different ways; the player is encouraged to make versions for different gongs, and up to three versions may be played in any performance. "Cyclone", which is always the central movement of the piece, consists of several pages, which may be arranged in different ways for each performance. "Bellbuoys 1" and "Bellbuoys 2" always start and end the piece, but the player may choose which is the start and which is the end; this choice affects the ordering of other movements in each performance. The core formal elements of the composition are set out in "Navigation", which is based on a set of rhythms based on sevens, and a different bell source, the patterns of Grandsire Triples, one of the many forms of the English change ringing tradition of church tower bells. The forms of the other movements are developed from these elements.

Throughout the piece the performer is asked to choose the instruments, and in some cases the playing techniques that best articulate the score. This is not a frivolous option; there is a huge variety of instruments available to modern percussionists, and an equally huge variety of playing techniques, so the precise possibilities will vary greatly from one performer to another. I have sought to construct the work in such a way that allows it to adapt to the particular capabilities of each player. At the same time, I hope to challenge and stretch these capabilities, so that the player also adapts to the piece. It is from this variability that the other choices in the score have grown.

The real time computer sound processing expands, elaborates and transforms the sounds generated by the percussionist. Live transformation of instrumental sounds has been my speciality for over forty years, and the techniques have grown in sophistication over that time, especially since the great increase in computing power in recent years. The transformations in this work reflect both the new capabilities of computer processing and the simpler techniques I have been using throughout my career. The techniques used will include complex dynamic delay systems, pitch shifting and spectral convolution. The sounds will be articulated over a multi-speaker ambisonic surround sound system.

The original inspiration for Bellbuoys comes from my memory of lying in my bedroom at our summer house by the sea in Sorrento on Frenchman Bay, Maine, and falling asleep to the sounds of the Sorrento Harbor Bell, the waves lapping on the beach and the wind in the trees. I have expanded these thoughts to ideas of the many different navigation aids and their characteristic sounds, and allied these to the sounds of the environment around them. Add to this a very long love of the sounds of bells of all kinds; it is from these beginnings that the work has evolved.

Lawrence Casserley February, 2013