How L.A. architect Paul Murdoch designed a 9/11 memorial that literally sings

When Paul Murdoch received the commission to design the Flight 93 National Memorial in 2005, he never imagined the job’s final stages would be taken up with figuring out how to build a massive — and massively complex — musical instrument. So, we wanted to do something in the memorial with sound.” “By using the wind, it’d be an ever-changing memorial expression,” he adds, “because it would alway reflect the changing conditions on the site.” The tower was to be outfitted with 40 aluminum chimes, one in honor of each passenger and crew member. “I thought we’d be making models and testing them in wind tunnels,” says Murdoch. “While you get a really robust sound when you strike a chime externally, internally you only have have a couples of inches to move the striker enough.” Acoustics expert Elizabeth Valmont of the design firm Arup, who worked on the project, told Popular Science the design was unprecedented: “Having a chime work like a bell, where there’s a hammer inside the tubes, had not been tested before.” They were able to devise a striker that worked efficiently. “The symbolism of those voices, that really speaks to me.” Murdoch says the story of the passengers and crew on Flight 93 is one that remains meaningful to him as well.