Accompanying music for a stage or film production which serves to establish a mood or stimulate appropriate audience responses. It differs from incidental music in not being part of the action, and in working on the listener subliminally.
The use of music as a media for psychological conditioning is prefigured in the 19th-century song without words, with Mendelssohn defending the view that music expressed a reality more definite than a poetic text. Magic lantern (early slide projector) entertainments accompanied by fragments of well-known works established a basis for the film score. Today, the use of piped music in shopping malls extends the principle to real life.