While every military project has its conspiracists, I found hundreds of Internet stories suggesting that the US government has been testing acoustic weapons on its citizens. The US government has its own conspiracy theories as well. Major Joseph Cook III has suggested in his handbook, Nonlethal Weapons, that the Russians have a gun that shoots 10-Hz acoustic bullets the size of baseballs from hundreds of yards away. It has been claimed for years that the Nazis developed a sonic cannon so powerful it could fell a B-17 bomber out of the sky. But these appear only as anecdotal stories. Of the acoustic prototypes that actually exist, several have actually proved viable. In his 1981 book Riot Control, Colonel Rex Applegate showcased a blueprint for a curdler (which he aptly nicknames “the people repeller”), which looks like a British police club and emits a shrieking, pulsating sound equal to 120 decibels at 30 feet. Swanson directed me to two weapons: a Compression Air Device [CAD] and a Ring Vortex Cannon. The CAD generates energy at a specific low frequency from a combustion engine at its base, and directs the sound out of a long tube. The Ring Vortex Cannon, which Swanson thinks is the most viable of the acoustic weapons, is actually an acoustic and kinetic cannon that sends out an infrasound donut-shaped shock wave combined with a toxic chemical spray. The vortex ring travels at hundreds of miles per hour, and hits its target with the force of a rubber blanket.