For the "PRINCIPIA" exhibition in the Dome Square, in Milan, during the International Furniture Fair, April 11 to 27, 2011, Hubert Westkemper curated a space (Holophonic Room) dedicated to 3D listening by means of Wavefield Synthesis
Holophony is the acoustic equivalent of holography where the Greek term oλος, holos, “all” evokes a dimension of enveloping spatiality, one of the objectives of this new technique known as Wavefield Synthesis (WFS), the creation of a field of sound.
Research and study began in the 1990s in the Netherlands at DELFT Technical University with A. J. Berkhout, D. de Vries and P. Vogel (Acoustic Control by Wave Field Synthesis) and M. M. Boone, E. N. G. Verheijen and P. F. van Tol (Spatial Sound Field Reproduction by Wave Field Synthesis).
The aim was to create sound sources and virtual spaces by means of authentic “audio rendering”, that would generate a sound field that could be used in an extensive listening area.
This approach marks a substantial innovation in how sound is diffused; while stereophony and sound-around combine positioning the loudspeakers to create a kind of psycho-acoustic illusion (which is concentrated into a very small area called the “sweet spot”), this new technique physically generates a new field of sound independently of the physical characteristics of the actual space it takes place in. The “sweet spot” gets extended to a very large area within which listeners may move around freely.
Voices, musical instruments and other sounds may be localised at varying distances or even in movement as though they were real. The collocation of these virtual sources is not strictly linked to where the loudspeakers are actually placed and under certain conditions it is possible to create a kind of sound holograph a few metres in front of the loudspeakers.
WFS generates these virtual sources by substituting the sound waves –which in reality spread out concentrically from a voice or instrument like the waves generated by a stone thrown into a pond – with “sound fronts” which are all curved identically and are directed towards the listener.
Beginning with a monophonic signal, the audio signals are generated by a sophisticated system of calculation and transmitted to dozens of loudspeakers lined up on a horizontal plane around the audience and which all perform together as though they were a single speaker.
WFS presently works at 360° on this horizontal plane but differently from cinema or home theatre sound systems, it is not bound to any preferential direction. Despite this configuration being greater in sensitivity of localisation than the human ear, I still wished to add verticality to the virtual space, both to provide a more complete acoustic involvement and to experiment with creating sound trajectories that would fly over the heads of the people in the audience.
Enthusiastic as regards the potential that I perceived in this highly advanced sound system which up to now had been relegated to research centres and European universities, and having had the effective functionality verified by IRCAM in Paris, one of the most advanced research institutions in technology applied to music, I resolved to bring it to Italy in order to try out its real applicability in a performance. The result of this first experimental phase was a theatrical study that took place in the Mercadante Theatre in Naples in 2010.
This experience led to a further challenge which today is tackled Nome StANzA 49 together with two composers who also felt stimulated to test this new spatial creative dimension of sound in movement.
This is how this sound installation came into being with two pieces of music: The Planets by Ludovico Einaudi already contains the image of planets revolving round the sun and the sense of spatiality in its compositional idea. The oscillating variation of the firmament can acquire three-dimensionality with WFS. Trajectories and orbits suggested by an electric piano with sweeping of strings and ‘cellos are created approaching and departing above the audience’s head like meteorites. The audience feels as though it is being physically brushed by sound and feels immersed in a cosmic space which is an integral part of its being.
The second piece of music Church of noise by Sir Bob Cornelius Rifo also provides an unconventional audition. Soaring strings make good use of the potential, not only frontal of WFS, a male voice firmly holds the central space while two female voices fly freely combining with the electronic drones and the musical fabric.
A play on sound perspectives which, by stimulating the imagination suggests and evokes states of mind memories and emotions in the listener.
Years of experience gained from experimenting in spatiality including a theatrical performance of Electra, in which the whole audience followed the subjective of the protagonist with binaural signal headphones enable me to assess and appreciate this new sophisticated technique which I intend to continue to follow in the future. I feel sure that sound which is generally relegated to a question of mere technique has much potential yet to be discovered. WFS provides the opportunity to enrich sound with inventiveness and three-dimensionality thus giving technology greater depth of meaning and its own worth in dramaturgical terms also.