Astro Spatial Audio Brings New Life to Mozart’s Requiem

One of the world’s most respected opera festivals has been transformed into a fully immersive production courtesy of Astro Spatial Audio, including the creation of highly reverberant, church-like room acoustics in an historic open-air courtyard theatre.

Founded in 1948, the Festival International d’Art Lyrique d’Aix-en-Provence returns to Southern France each summer with an innovative programme designed to equally challenge and delight the international opera community.

Productions can range from newly commissioned pieces to bold new interpretations of the classics, filling the Théâtre de l’Archevêché with eager audiences. The theatre is literally housed within the courtyard of the former Archbishop’s palace, where some 1,600 spectators fill two tiers of seating surrounded by the walls of the palace with an open sky above. For more than 70 years, the location has evolved into one of the world’s most unique and beautiful opera venues, but for the 2019 production of Mozart’s Requiem, director Romeo Castellucci and conductor Raphaël Pichon were set on creating an immersive experience that truly evoked the spirit of Mozart’s work.

“The vision was to immerse the audience within the original acoustic context of the Requiem – to help the audience feel as if they were really in a place of worship,” explains audio consultant Rémy Brean. “Of course, that meant altering the acoustic parameters of the Théâtre de l’Archevêché, which is beautiful but certainly not a cathedral! It actually has a short reverberation time so we knew that to increase it we would have to adopt an artificial solution. Our main objective was to create a reverberant environment that didn’t sound as if it was being produced electronically, but was as natural as possible.”

Further challenges were presented by the theatre’s historical status and the need to respect its aesthetics, including the impossibility of suspending loudspeaker enclosures above the audience. The relatively steep upper seating tier also resulted in an under-balcony area that proved hard to cover.

Romeo Castellucci’s inventive, immersive approach to the production further drove the concept, with the soloists and choir positioned in varied locations including behind the audience. Similarly, the choir was conceived of as mobile, moving through the performance and even dancing during sung passages. “Given the style of the production we decided that in addition to changing the acoustic character of the venue, we would use 3D sound localisation for vocal and instrument sources,” says Brean.

Bringing the vision to reality, Brean turned to Astro Spatial Audio. “The reasons for choosing Astro Spatial Audio were clear,” he continues. “It supports Dante, it provides interactive dynamic room acoustics and integrated object-based 3D immersive sound at a very high quality and it has very low processing latency so it’s ideal for live performance. Most significantly, it is compatible with every brand of loudspeaker, so we had the freedom to use the equipment that we really wanted.”

Using AFMG’s EASE prediction software, a discreet network of Fohhn Linear Focus Series loudspeakers was positioned around the theatre, which was divided into three acoustic zones covering the orchestra, the under-balcony area and the balcony itself. For the interactive room acoustics, 38 loudspeakers were located throughout the venue, covering the orchestra, the performers on stage, soloists and the choir, all of which were directly fed into the Astro Spatial Audio Room Simulation Software module (RSM Pro).

The RSM Pro module is part of the SARA II Premium Rendering Engine, the hardware heart of the Astro Spatial Audio solution, facilitating the conversion of audio signals into audio objects. Measuring just 3U but delivering up to 128 MADI or 128 Dante configurable network pathways, the award-winning SARA II uses extensive metadata to precisely calculate each object’s position within virtual 3D space over 160,000 times per second, as well as that object’s acoustic effect on the virtual space around it.

“Reinserting the sources into the sound reinforcement system proved particularly complex because we had to mesh the naturally propagated sound of the performers with our artificially reconstructed sound field,” says Brean. Nevertheless, he adds that the result was transformative. “Put simply, for me Astro Spatial Audio is the best immersive solution available.”

“This year was the first time that the Aix-en-Provence Festival trusted in immersive 3D sound and interactive room simulation technology and I consider it an honour that they chose to work with us,” enthused Astro Spatial Audio Managing Director Bjorn Van Munster. “This is another example of how true object-based audio can bring an entirely new dimension to even the most traditional live performance.”

In conclusion, Brean adds that the experience has left him wanting more: “I will use Astro Spatial Audio again as soon the next opportunity arises.”

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