1. The perceived source = the real source:

   In the first category one might find some industrial music in which real machinery used in a musical context functions as a signifier of real machinery, or in an electroacoustic piece where the sound from a loudspeaker is used to signify a loudspeaker. This is the case in the recent fashion, both in electroacoustic circles and in more adventurous avant – garde popular music, for the ‘glitch’ piece – music made of the sounds of malfunctioning audio equipment. In my own piece The Killing Floor, originally written as a score to the William Gibson inspired contemporary dance work by Richard Lord entitled Hamsters in Mirrorshades, the image of technology on the brink of breakdown is conjured by noises, pops and distortions, which at first sound disconcertingly like the sound system cracking up. The audience is at first unsure whether they are hearing a piece about technology breaking down or whether they are merely hearing technology break down. In the context of the piece this unease may resolve as the glitches become accepted as part of the language of the piece.

2. The real source (i.e. the loudspeaker) is concealed:

   The second category in which the loudspeakers are concealed is exemplified by a section of the 1995 installation H.G. in Clink Street Vaults, London by Robert Wilson and Hans Peter Kuhn (ArtAngel commission) in which one room contained nothing but the eerie sound of footsteps on the ceiling above, pacing to and fro across the creaky floor boards. Of course these were recorded sounds played through loudspeakers in the room above, but the illusion was real enough to raise doubts in the listener’s mind, and only after some considerable time did the repetitive pattern of the footsteps give the game away.

3. The sounds in the music belong naturally to the performance environment:

   In the third category one might find pieces containing birdsong played in outdoor locations or pieces involving crowds played in public places. The effect was for example very noticeable when I played an early composition of mine entitled Crowd Control, in the foyer cafe of the York Theatre Royal. As the piece opened with the sounds of voices approaching it was some time before the audience became aware that there was a piece being played. The Whitechapel soundwalk discussed above is another example of this category.

The Anxious Boundary in Living Steam

Living Steam uses all three of the above techniques to blur the boundaries between the work and its surrounding reality:

1. Some of the sounds are being made by the actual engines during the performance.
2. Speakers are concealed among the engines making them hard to spot.