Why NASA's Jet-Noise Dome Is Lined With 17,000 Fibreglass Wedges
NASA Glenn's Aero-Acoustic Propulsion Laboratory is a 65-foot-radius geodesic dome with two jobs: reducing community noise and running aeroacoustic tests on aircraft engines and engine components. Nothing echoes during a test, because 17,000 custom-designed fibreglass wedges — each two feet thick — line the inside surface of the dome and sit on the floor and around the test rigs, absorbing sound rather than reflecting it back.
When the lab was built in 1993, it was the first known free-standing geodesic dome to include materials meant to stop sound passing through the walls and to soak up sound within them.
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The silence is engineered, not architectural. A dome is a shape; what makes this one usable for measuring noise rather than bouncing it around is the wall of two-foot fibreglass wedges.
That 1993 milestone is narrower than it sounds: the first known free-standing geodesic dome combining sound-blocking and sound-absorbing materials, not the first acoustic chamber. The curious part is how long it took anyone to put a serious silencer inside a dome.