Better theatre sound through proper loudspeaker placement
Sound for the theatre? Simple - put loudspeakers at the sides of the stage and play everything through them like a big hi-fi.
Wrong! But let's explore the issue...
Here, I am talking about a theatre drama production that uses sound effects and incidental music, but the actors do not have microphones. As an example, I have chosen The Ghost Train by Arnold Ridley - a play that allows both sound and lighting designers to show off their skills to the full.
As you might guess from the title of the play, a train is involved. Since the play was written in 1923, the train will be pulled by a steam engine. In a conventional production, the scene will be the waiting room of a provincial railway station, with windows in the rear wall of the set looking out onto the station platform. It is through these windows that the train will be glimpsed, but not clearly seen.
The challenge for the lighting designer is to make it look as though a train is passing by outside - without having to build one! We'll leave that to the lampies and move on swiftly to the sound.
In the original production, the sound of the train was created mechanically. Today, it makes sense to use a recording of a steam train. Ideally this will be created specifically for the production.
It is also likely that there will be incidental music, at least to open and close the acts of the play. Some productions of other plays might use incidental music more frequently.
Why not play everything through the same speakers?
At this point, we have the sound of the train and some incidental music. You could place two loudspeakers at the sides of the stage and play all of the sound through them.
But this is not the right thing to do. So why?
The answer is to be found by considering what the characters of the play can hear. They can hear the train, but clearly the characters do not hear the incidental music. There is no orchestra or band in the station waiting room! Only the audience hears the incidental music. (Clearly the actors hear it too, but the characters of the play do not. That is an important distinction.)
Following this logic to a sensible conclusion, the sound of the train should come from where the train is meant to be - outside of the waiting room. So that is where the loudspeakers should be.
It may be thought that putting the loudspeakers behind the set, a long way from the audience, isn't quite the right thing to do. But it absolutely is. The amplifiers should be powerful enough, and the loudspeakers beefy enough, to create a sound that is believably, in the context of theatre, a train. And the sound of the train should be coming from the tracks, not speakers at the front of the stage.
Where should the incidental music come from?
So now, the finesse... The incidental music should come from loudspeakers at the front of the stage. This is outside of the acting area and is therefore separated from the drama. The incidental music is for the benefit of the audience and the characters should not appear to be able to hear it.
In summary therefore, sounds that are heard by the characters should come from loudspeakers positioned within the acting area, where those sounds would be heard by the characters (remembering the distinction between the characters and the actors). Incidental music should come from separate loudspeakers closer to the audience than the acting area. These speakers should not be used for any sounds that would be audible to the characters. This principle applies to almost every non-musical theatre production.
Which leaves just one question...