Music in a play (or to a lesser extent a musical) serves a very different purpose to music in a film or at a concert. In fact, it has a variety of purposes depending on the play that it is part of.
I have based these purposes on the great book Sound and Music for the Theatre: The Art & Technique of Designby Kaye and Lebrecht. Their main framework divides all theatrical sound into four categories: Framing Cues (overture, intermezzo, preshow sound); underscoring; transitional music/effects (indicating a shift in time or space), and specific cues.
These cues exist in the theatre, but not in the narrative of the play. They are used to transition between the outside world and the exciting world of the story. At the most basic it can be a preshow playlist of old recordings to set the atmosphere for a WWII play, to full blown orchestral Overtures and Intermezzos.
A substantial (although often brief) standalone musical work played before the narrative starts. It usually introduces the musical and aesthetic themes of the proceeding drama.
An intermezzo is an piece of music played between scenes or acts. Designed for a practical purpose—to cover a gap while the stage is dark and the set and costumes are changed—it usually also evokes the following scene, or provides a musical reflection on the scene before it.
Many composers and designers no longer use overtures or intermezzos in their work, which is a shame, as some of the greatest works in the canon started life as theatrical framing cues (William Tell Overture, Mendelssohn’s Nocturne).
Underscoring refers to music which plays underneath dialogue and action, without ‘locking in’ with it or standing on its own. Generally quiet and unobtrusive, it supports the onstage action emotionally and atmospherically. It is not usually heard by the characters onstage.
Rather than dealing with melody or structure, many theatrical writers speak of the importance of ‘atmosphere’. This rather nebulous quality is seen as an effort to reflect the setting and feel of the scene through music, and can be seen as the musical equivalent of scenography. I draws from the techniques and functions of underscoring, but develops into a more ambient and unobtrusive sound. Norman O’Neill, a prolific theatre composer, concluded: “Music should step in where the play itself, the actors and the stage effect, can no longer carry on the illusion. And it is just in such cases that the composer can work wonders and create atmosphere and effects which may be unique in their way”
These are used to indicate time or spatial shifts within the narrative. This can be as simple as the “magical harp” found in 80’s TV shows everywhere, to more extended musical cues to indicate the passing of time or the move to a different location.
These cues are ones which occur within the world of the characters: they enter a club, so dance music plays; someone sings a song to someone else; the radio is on. Any music which is called for in the script or which occurs within the fictional world onstage (rather than in the theatre full of audience members) can be seen as a specific cue.
What do these mean?
These distinctions are made by writers such as Kaye and Lebrecht based on the narrativistic properties of the music. Does it exist inside or outside the story? The basic division of this is ‘can the character hear it or not?’. However, this then overlooks any more complex music such as melodramas (the subject of an upcoming post) or musical illustration. Likewise, others make the distinctions between exactly reproduced or artistically interpreted sound. The problem with most of these frameworks is that they are based on a modern understanding of acting and drama drawn from the Stanislavski School and the American Schools of Acting: the ‘method’ by which an actor ‘becomes’ the person they are playing, and is ‘motivated’ by the cues and people around them. Theories like this are influenced by filmic theories such as diegesis as well as filmic ideas of realism. This is also seen in early 21st century frameworks, such as many of those presented by Ross Brown (Sound: A Reader in Theatre Practice), that insist that the stage-technician must ‘feel’ the sounds to imbue it with the correct magical qualities. While these frameworks make sense when dealing with sound and music for contemporary modern theatre, these divisions break down rapidly when looking at anything from an earlier era, or when the division between ‘world’ and ‘entertainment’ isn’t as clear. They also break down when looking at any modern form of theatre which is not based on psychological realism (as many forms are).
However, these divisions provide a useful way of thinking about the music for the theatre, and can be used by composers, designers or directors as a framework for setting out their project.