Andermatt Concert Hall in the Swiss Alps, which opened its doors a couple years ago by hosting a performance by the Berlin Philharmonic, has been outfitted with an active acoustic and immersive sound system incorporating 75 CX41 loudspeakers and eight CX/CA118S subwoofers from Renkus-Heinz to cover both the performers and audience.
The concert hall offers seating for audiences of up to 650, with enough room for a 75-piece orchestra. The hall’s stage and lower level are below ground level, and the space is topped by a high ceiling with upper-level walls of glass, wood-finished ceilings, and a wrap-around balcony. Studio Seilern Architects created the captivating space, integrating acoustically optimized “origami” panels to provide an immersive acoustic signature. A new enhanced acoustic system was also deployed to increase the subjective volume of the space for varying performances.
To address acoustic challenges, Andermatt Swiss Alps brought in KahleAcoustics, specialists in space acoustics for concert and performance venues, as well as Amadeus Active Acoustics, developers of the Amadeus multi-channel, acoustic and immersive sound system. Evan Green, Acoustician Associate at KahleAcoustics, states that the challenge with a large orchestra, especially in a relatively small space, is how to control the sound level from being overwhelming. The sound pressure level generated by a full orchestra in a concert hall can be quite high
“Once you have a fixed volume, the way you make it quieter is to add sound-absorbing elements and surfaces,” Green notes. “But when you do that, the room becomes less reverberant, less resonant and the sound has less life to it, so we recommended a room enhancement sound system approach.”
A room enhancement system involves installing numerous loudspeakers that fully surround the audience to create an enhanced version of the hall’s acoustics. In the case of the Andermatt Concert Hall, the immersive sound processing system from Amadeus Active Acoustics uses 32 microphones to pick up all sound within the hall. Those signals are individually processed with natural active acoustic algorithms and then routed to the discreet Renkus-Heinz loudspeaker and subwoofer channels.
“Our ultimate goal is that the performers and audience are never aware that any of this is happening,” says Fabio Kaiser, Principal Acoustician, Amadeus Acoustics GmbH. “The space simply sounds like the natural acoustics of the room, but it’s created in a way that doesn’t add to the loudness issue. The natural acoustic character is still very present, and the scale of the room is expanded and enhanced by the active acoustics system.”
The 75 CX41 loudspeakers are strategically installed throughout the hall, color-matched with the walls, wood accents, and ceilings. They’re also located behind acoustically-transparent screens, making them virtually invisible. The CX41 is a very compact, two-way, non-powered loudspeaker designed to deliver 100 Hz to 20 kHz frequency response and 150- x 150-degree dispersion. “The sound quality, size, width of dispersion pattern, and frankly, the affordability of the CX41 loudspeakers make them a perfect choice for this application,” Kaiser says. The CX/CA118S 18-inch subwoofers are installed provide added sub-bass energy down to a stated 35 Hz.
“It’s important for musicians to feel that they’re inhabiting the same space as the audience, so we need to make sure every direction is covered, and everyone gets sound from every direction, so they feel completely enveloped in sound,” he concludes. “When you attend a performance at Andermatt Concert Hall, the system is on, but it just sounds like the natural sound of the room. Extremely high-profile musicians have performed here who been astounded by the active acoustics in place.”
