Earlier quoted context omitted.
This post and your comment has me thinking about STFU, posted here a couple weeks ago. https://news.ycombinator.com/item?id=46649142 Is it feasible to capture and directionally pipe audio back to a rude neighbor? Seems like it could be effective.
Been around for awhile: https://www.holosonics.com
ah, so this is what they used in embassy attacks