The Drone Shield could help one avoid potential security breaches, where it comes in the form of a portable black box which will perk its digital “ears” to listen for drones that are flying in the air, followed by alerting the owner should one (or more) be nearby. I would think that this is useless against the military class drones since those fly a whole lot higher and could feature classified stealth technology, so terrorists living in a cave somewhere might want to give the Drone Shield a miss.
The Drone Shield has been specially designed to pick up the characteristic acoustic signatures of various drones, being accurate enough to ignore ambient noise that is created by loud gardening equipment, including the likes of lawn mowers and leaf blowers. The asking price stands at $100 a pop if you’re interested. [Product Page]