Chapel of Sound

In the shadow of remains from China’s Great Wall, a new cave-like concert hall aims to offer visitors an acoustical experience like no other—while revitalizing the remote mountainous region that surrounds it. Located in Chengde, the Chapel of Sound was designed to look almost like a prehistoric boulder had landed in the spot long ago. But that belies the planning it took Beijing’s Open Architecture to complete the project. 

“We were very aware of the responsibility we had to contribute a thoughtful structure that fits naturally into such a unique landscape,” Open founders Li Hu and Huang Wenjing said. “We wanted to create something different, and more importantly, something meaningful. We are now at a time that the question of our relationship with nature as human beings is more acute than ever. Can we be humble enough to hear what nature is murmuring to us?”

Open worked closely with structural and engineering giant Arup to design the hall’s amphitheater, stage and viewing platforms. And throughout the process, the team let nature and the site’s geology influence and inform the design. “Interestingly, this is the only acoustical space we built without conventional acoustic material,” said Wenjing in a lecture. 

To minimize the project’s footprint, the team chose a layered design with an inverted umbrella shape. The tapered structure was built using an aggregate of crushed local rocks and concrete to mimic the valley’s craggy, sedimentary rock formations while also reducing material consumption. Winding staircases weave through the building—leading to a rooftop platform that offers panoramic views of the valley and Great Wall.

Turning the geometrically complex design into a structure that could actually be built required close collaboration between design and engineering—right from the start. Arup’s structural engineers used a 3D scanned file of Open’s model to finetune the design. One big challenge? Getting the thousands of timber plates—in different shapes—to fit together like a jigsaw. And then there were the 10,000 rebars—again, all different—that had to be bent and fixed into position.

The team knew it couldn’t skimp on sound, of course. So it enlisted an acoustic engineer and used digital optimization technology when designing the concert hall’s cavernous interior—a space inspired by the contours of shells, wooden instruments and the human ear. The “inner shell” optimizes sound quality with a stepped hard surface that functions as acoustic scattering panels. “We studied a lot about how sound would reverberate in chambers,” Wenjing said. Openings in the roof and walls of the building were strategically placed to prevent unwanted reverberations and reduce echo, while allowing in natural sounds and stellar views. 

A home for large-scale performances, the Chapel of Sound could help boost the local economy by drawing tourists to the valley. Yet Open’s architects hope the project also offers a tranquil destination for quiet reflection— “to be protected in the space in nature, and quiet down, calm down and be able to hear the wonderful symphony of nature,” Wenjing said.

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