Orchestral Reduction

An orchestral 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 piano or organ), 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 reduction or piano 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.