Editing Piano Phase (section)

==Analysis==
''Piano Phase'' is an example of "[[Process music|music as a gradual process]]," as Reich stated in his essay from 1968.<ref name=Reich_b>Steve Reich, "Music as a Gradual Process", in ''Writings on Music 1965–2000'', Oxford and New York: [[Oxford University Press]], 2002, pp.&nbsp;34–36.</ref> In it, Reich described his interest in using processes to generate music, particularly noting how the process is perceived by the listener. (Processes are deterministic: a description of the process can describe an entire whole composition.<ref name=Reich_b /> In other words, once the basic pattern and the phase process have been defined, the music consists itself.)

Reich called the unexpected ways change occurred via the process "by-products", formed by the superimposition of patterns. The superimpositions form sub-melodies, often spontaneously due to echo, resonance, dynamics, and tempo, and the general perception of the listener.<ref name=Epstein>Paul Epstein, ''Pattern Structure and Process in Steve Reich's Piano Phase'', [[Oxford University Press]], The Musical Quarterly 1986 LXXII(4):494-502.</ref>

According to musicologist Keith Potter, ''Piano Phase'' led to several breakthroughs that would mark Reich's future compositions. The first is the discovery of using simple but flexible harmonic material, which produces remarkable musical results when phasing occurs.<ref name="Potter"/> The use of 12-note or 12-division patterns in ''Piano Phase'' proved to be successful, and Reich would re-use it in ''[[Clapping Music]]'' and ''[[Music for 18 Musicians]]''. Another novelty is the appearance of rhythmic ambiguity during phasing of a basic pattern. The rhythmic perception during phasing can vary considerably, from being very simple (in-phase), to complex and intricate.<ref name=Epstein />

The first section of ''Piano Phase'' has been the section studied most by musicologists. A property of the first section of phase cycle is that it is symmetric, which results in identical patterns half-way through the phase cycle.<ref name=Epstein />