I can think of no better demonstration of this adaptation than this video and microphones used to listen to bird flight. Two birds—a pigeon and falcon—make a ton of noise while flying, while the barn owl’s flight is inaudible. The pigeon makes more noise than the falcon, for there’s no advantage to a pigeon flying silently, while there’s probably a marginal advantage for the falcon to tone down its approach. But owls hunt at night, when prey are keenly attuned to the sounds of danger, and so owls have developed a new weapon in the arms race.
How do owls do it? The key is their uniquely serrated wing feathers, which you can read about here.
From the BBC show Super Powered Owls (sadly, you can watch it at the site only if you’re in the UK).