Do drones' characteristic lawnmower-on-helium sounds drive you batty? You're not alone. NASA researchers have conducted a study indicating that people find drone noise more annoying than that of any ground vehicle, even when you put the two at similar volumes. It was roughly equivalent to a car being twice as close as before, according to the researchers. And while there were just 38 people in the test, none of them were told what they were hearing or what the study was accomplishing. The results seem obvious if you've ever heard a drone, but there's a big question: why are they so irritating when cars create plenty of aural annoyance on their own?