Orchestrion is a generic name for a machine that plays music and is designed to sound like an orchestra or band. Orchestrions may be operated by means of a large pinned cylinder or by a music roll and less commonly book music. The sound is usually produced by pipes, though they will be voiced differently from those found in a pipe organ, as well as percussion instruments. Many orchestrions contain a piano as well. At the Musical Museum in Brentford, examples may be seen and heard of several of the instrument types described below.
It is confused by some with the steam-powered calliope, which was also used to produce music on period carousels. It used steam whistles rather than organ pipes to produce its principal sounds. See also the similar fairground organ.