A long time ago, I read a story about a future war. Everything is in ruins. An old lady is trying to raise a boy. But one weapon has made everyone deaf. When the boy does something bad, all she can do is hold up a card which says "No!". They can tell when the air raid siren goes off by the vibrations of the sirens causing beans to jump about in a tube. TV shows lots of old silent movies.
It may have been in an anthology.