Every owl fancier has a story of the first time they heard an owl — or, rather, didn’t hear one. It’s unforgettable to see an enormous bird, whose wingspan can reach more than six feet, slipping through the air without even a whisper.
Justin Jaworski’s first close encounter came at a flying exhibition at the Raptor Foundation near Cambridge, England. “They trained the owls to fly very close to the audience,” he says. “My first experience was of ducking to avoid a collision. I heard only a very slight swoosh after it passed.”
Laboratory measurements have shown that the slight swoosh made by a barn owl is below the threshold of human hearing until the owl is about three feet away — a feat of stealth that biologists and engineers are far from completely understanding. But researchers from both disciplines are working to solve the riddle of silent flight — some with the aim of designing quieter fans, turbine blades and airplane wings.