A single question has been beckoned over and over again by the sound of warfare becoming the whine of drone props.... which is that certainly the proliferation of this sound is a coin with another side, the other side being that dispersed low power drone detection networks should be very easy to implement effectively at scale with cheap microphones.

Microphones of all kinds are cheap, (we have the music industry to thank for that) and they can be dropped by helicopters or larger unmanned aircraft over large areas to serve as semi-permanent sensors to detect drones long before they get where they are intending to go.

It will become a necessity for most drones to become much quieter unless they are drones used right at the leading edge of combat where everything is noisey.