Incidental music is music used to accompany a dramatic performance. It may be utilized for plays, radio shows, films, and television, and incidental music is often a very important part of a production, especially in the film world. Depending on the production, the incidental music can be composed specifically for the production, or already existing music may be used; when incidental music is commissioned specifically for a performance, it can be expensive for the producers.
The idea of incidental music is quite ancient: the Greeks, for example, used incidental music in their plays, drawing upon the rich body of ritual liturgy to enhance the look, mood, and feel of their performances on the stage. Many ancient Asian dramatic arts also utilize incidental music, and, as with the Greeks, the music often had very specific symbolic meaning which would have been well-understood by members of the audience.
The popularity of incidental music in performance has waxed and waned historically, but never vanished entirely. This could be considered a testimony to the power of music, because music can completely alter the mood and tone of a piece in a way which could not be accomplished otherwise. Music can brighten a scene, create tension, or underscore the sadness or horror of an event, and some incidental music has gone on to be famous in its own right. Many classical composers, for example, composed pieces for plays and other performances which later came to be used in standalone performance.
Incidental music fills the intervals between scenes and acts, works as a background for dialogue, and sometimes becomes the star of a scene, as in the case of a dance scene in a movie. Composition of incidental music can be very challenging, as the composer must be able to evoke the desired mode while working within very specific scene and time constraints. Depending on the project, a composer may work alone, with synthesizers and other tools, or he or she may utilize a suite of musicians ranging from a quartet to an orchestra to get the desired sound.
Characters are often enriched by the incidental music which accompanies them, with many major characters having their own themes. Composers may also create musical themes related to specific events in the performance, like a love theme for two characters, or a theme which is meant to evoke the antagonistic relationship between two characters. While viewers and listeners are often unaware of the importance of incidental music, being aware of it while absorbing a performance can be very revealing.