A voice jammer can now stop anyone recording the speech of a single target person.
Voice jammers work much like noise-cancelling headphones, which effectively squash unwanted background sound waves out of existence by playing a copy of a background sound wave but with the wave pattern inverted. Such jammers generally stop electronic eavesdropping on conversations by broadcasting inverse sound waves that affect all microphones within earshot.
But this can prevent nearby people’s phones from picking …