4 instruments (and bass drum ad lib.)
Ripple Marks (1999) is based on a melodic theme that develops on the first instrument (3 notes, then 5, then 7, then 9, then 5 and finally 3) while the second instrument plays a pattern consisting of the same notes as the theme of the first, but written in regular values (sixteenth notes) in the high register.
The regular eighth notes of the third are the same motif, but in retrograde movement, and the fourth plays a single pedal note (low E) in irregular long values punctuated by the bass drum. Slow and collected, the ensemble gives an impression of polymetry due to the staggered accents of each instrument.
Clarinettist Ronald Van Spaendonck has made a superb recording in a version for clarinet and bass drum ensemble.