Focusing specifically on microtonal pulse modulation, Chaser is the fourth in a series of works based on sine-pulse phasing. The work consists of two parts that take a look at two different solutions to rapid continuity over ever-changing backgrounds. 

One movement (with the soloist on glockenspiel plus various subsidiary instruments) focuses on oscillation and is based on a small repertoire of mallet patterns with rapid movement in tremoli or rapidly changing chromatic figures. At tempo 60 bpm, the music moves up a minor tenth in fourteen isochronous sections as the ensemble gradually extends its range downwards. Followed by a harmonic transformation, the second movement (which includes the soloist on marimba and bass drum) takes the same formal procedures as the first, but transforms them into ascending heptatonic scales, gradually moving down over a chromatic octave and, at the end, exhausting the full set of possible scales. The work plays a little game with tempo changes, initially starting at tempo 60, then adding tempo 61 as the ensemble drops to tempo 58. The title derives from the soloist’s relentless pursuit of the microtonal pulse modulations as the ensemble follows: anticipating, following or consolidating but also pursuing the pursuer. 

Peter Adriaansz