Impetus is a six-minute single movement piece for orchestra consisting of 3 flutes (3rd
doubling piccolo), 2 oboes, English horn, 2 clarinets in Bb, bass clarinet in Bb, 2 bassoons,
contrabassoon, 4 horns, 3 trumpets, 3 trombones, tuba, timpani, 3 percussion, harp, piano, and
strings. The title is in reference to the interjections that take place throughout the piece, which
may cause the preceding material to drastically change, or at times not change at all.
The piece is in three large, contrasting sections, each connected by two different types of
transitions. The first section involves a quiet, dense, slow moving texture using quarter-tones.
This density is interrupted—but not affected—by loud, abrupt interjections from the entire
orchestra. The second section is a loose reflection of the first; however, the loud, abrupt
interjections do change the preceding material. This section is fragmentary and episodic,
alternating between the orchestral interruptions and material differing completely in
instrumentation, timbre, dynamics, and character. The third and final section begins with slow,
quiet swells transferred throughout the orchestra. It also features sound-based techniques that
have not been used at any other point in the piece: air sounds, scratching/rubbing parts of the
instruments, and key clicks. Through the use of these techniques, references to the first section
will take place; however, these references are blurred and ultimately unrecognizable.