A sailor in the US Navy uses a long-range acoustic device during a drill David Wa / Alamy
A non-lethal device developed by the US Navy aims to surreptitiously render a person unable to speak.
The device, called a handheld acoustic hailing and disruption (AHAD) system, records a target’s speech with a long-range microphone and plays it back to them with a tiny delay. As anyone who has spoken on a phone or internet call that echoes their voice back at them will know only too well, such delayed auditory feedback can be highly disruptive …