This appendix introduces three of the most famous diffusion systems, including:
the Birmingham ElectroAcoustic Sound Theatre (BEAST) (Section II.i), The Acousmonium (Section II.ii) and The Cybernéphone (formerly the Gmebaphone) (Section II.iii).
II.i Birmingham ElectroAcoustic Sound Theatre (BEAST)
The BEAST diffusion system can be adapted to receive an input from numerous different audio sources, such as a CD player, DVD player, a live input or, as is most often the case, a computer programme with acousmatic works pre-loaded.
BEAST, like all diffusion systems, has an intermediate control interface that regulates the signal being sent from the audio source to the loudspeakers.
However, this particular system uses a purpose-built mixing desk with sets of faders controlling the level being sent to each loudspeaker (Harrison 1999b, p.124). The intermediate control interface regulates the signal being sent to a loudspeaker array which is based upon eight loudspeakers (discussed in Section 2.1) known as the “main eight” (Harrison 1999b, p.121).
The loudspeaker array used in the BEAST system is, in many cases, expanded way beyond the main eight loudspeakers. However, at this stage there is no standard loudspeaker arrangement (although certain arrangements may be commonly found). Instead, the number and position of loudspeakers used within the array will depend upon the concert space that is being used; some spaces require more loudspeakers than others and it is not possible to arrange loudspeakers in a standard format as concert spaces invariably differ in their shape and size. With this in mind, the BEAST system may be adapted to include side speakers in long, thin spaces, additional centre speakers in wide spaces, elevated front/rear speakers to fill lager spaces, distant/close speakers to create the impression of proximity, and so on (Harrison 1999b, pp.122-123).
The BEAST system benefits from various grouping options which enable sets of loudspeakers to be activated with individual faders. These
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grouping options are extremely useful when dealing with large number of loudspeakers but invaluable when dealing with multichannel works, since they enable the performer to make smooth and straightforward transitions between various different multichannel rings within the array. In addition to this, the BEAST system offers various pre-set configurations and transitions; whilst these prove to be extremely useful when diffusing works on a large system their use requires a substantial investment of time on the part of the diffuser.
II.ii The Acousmonium
The Acousmonium, a system devised by François Bayle and Jean-Claude Lallemand at the Groupe de Recherches Musicales (GRM), may include up to eighty loudspeakers in a single performance. This system is often referred to as an orchestra of loudspeakers in response to the (partially) asymmetrical distribution of non-homogenous loudspeakers resembling the groupings of instruments found in an orchestra. The distinct characteristics of the various loudspeakers are central to the Acousmonium and differentiate this system from certain other systems which have symmetrical, homogenised loudspeakers; for Savouret, this affords a kind of variable shading that other systems do not necessarily permit:
One notices a certain rejection of the idea of an ensemble of high-fidelity rigorously homogenized loudspeakers, possessing a near-military precision of performance and behaviour in their devotion to the common cause of the composition. To this totalitarian concept of sound-projection, I prefer the high-infidelity of loudspeaker pairs that allow variable shading during the diffusion. To the autism of an ensemble of identical loudspeakers, I prefer the multiracial accents of a disparate gathering.
(Savouret 1998, p.347)
The Acousmonium employs a mixing desk with faders as a control interface.
However, given the large number of loudspeakers used in this system, individual faders are often used to control loudspeaker groups (Mooney 2005, p.201).
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Thus, by raising individual faders, one is able to activate different sections of the loudspeaker orchestra and thus diffuse the work.
II.iii The Cybernéphone (formerly the Gmebaphone)
Christian Clozier has sought to clearly differentiate the Cybernéphone, formerly called the Gmebaphone, from the Acousmonium; Clozier does not describe his system as a diffusion system or an orchestra of loudspeakers, but as:
[…] a huge acoustic synthesizer, an interpretation instrument that the composer plays in concert, an instrument that serves to express his composition, to enhance its structure for the benefit of the audience, to bring it to sonic concretization.
(Clozier 1998, p.268)
In this context, the term synthesizer is used in reference to the Cybernéphone’s bespoke frequency splitting device, known as the Gmebahertz; this subdivides an encoded audio signal into multiple frequency bands which are then distributed to the loudspeaker array (Emmerson 2008, pp.151-152). The array does not have a standard configuration but typically consists of around fifty loudspeakers with limited frequency response bands; the encoded audio signal is subsequently reproduced by loudspeakers with different frequency responses in different locations, thus: “[...] ‘spatializing’ it through frequency distribution [...]” (Emmerson 2008, pp.151-152).
The Cybernéphone uses a bespoke mixing desk as an intermediary control interface. However, there are two primary user interfacing modes which Clozier describes as: “manual mode” and “computer-assisted diffusion mode”
(Clozier 1998, p.269). In manual mode, the performer has direct control over the signal being sent to a particular loudspeaker via a fader, whereas the computer-assisted mode allows various pre-set fader movements to be triggered during a performance. These pre-sets may be recorded in real-time, directly from the faders, or developed offline using a bespoke interface. Either way, computer-assisted diffusion mode enables the performer to realise highly specific agential acts that would be difficult to realise during a performance.
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