(a) first four measures of Bach's Preludium in C major (BWV 846a). (b) and (c) block chord reduction and voice leading reduction ease analysis and practiceFull score of the "Lacrimosa" from Mozart's Requiem. playⓘTwo-hand piano reduction of the "Lacrimosa" from Mozart's Requiem, arranged by Franz Liszt. playⓘ
Anorchestral reduction is a sheet music arrangement of a work originally for full symphony orchestra (such as a symphony, overture, or opera), rearranged for a single instrument (typically pianoororgan), a smaller orchestra, or a chamber ensemble with or without a keyboard (e.g. a string quartet). A reduction for solo piano is sometimes called a piano reductionorpiano score.
During opera rehearsals, a répétiteur (piano player) will typically read from a piano reduction of the opera. When a choir is learning a work scored for choir and full orchestra, the initial rehearsals will usually be done with a pianist playing a piano reduction of the orchestra part. Before the advent of the phonograph, arrangements of orchestral works for solo piano or piano four hands were in common use for enjoyment at home.
A reduction for a smaller orchestra or chamber ensemble may be used when not enough players are available, when a venue is too small to accommodate the full orchestra, to accompany less powerful voices, or to save money by hiring fewer players.
Apiano reductionorpiano transcriptionissheet music for the piano (apiano score) that has been compressed and/or simplified so as to fit on a two-line staff and be playable on the piano. It is also considered a style of orchestration or music arrangement less well known as contraction scoring, a subset of elastic scoring.
According to Arnold Schoenberg, a piano reduction should "only be like the view of a sculpture from one viewpoint", and he advises that timbre and thickness should largely be ignored, since "the attempt to make a useful object equally usable for a variety of purposes is usually the way to spoil it completely".[2]
