For years now, law enforcement and military groups have been perfecting weapons that use audible and ultrasonic frequencies to deter or harm their targets.
Using loud sounds, LRAD, or Long Range Acoustic Device, warns vessels that do not answer to radio orders to keep clear of naval ships. The range of these 'weapons' is very large. Sounds can dissipate due to atmospheric conditions or variations in topographical features.
Local police have been using a device that they use in conjunction with their sirens. Some have dubbed it the 'thumper', citing the thumping pressure that the target of the sound feels when it's directed toward them. The cops started using this device to gain the attention of someone they are pulling over in case the driver is blasting the music inside the car at very high levels or deaf. This 'thump' is an ultrasonic pulse emitted from an added device from under the police cruiser's hood.
Crowd control devices have also evolved to include sounds. No more wasting precious water resources by washing riotous crowds down with fire hoses. Now the masses can be targeted with an ultrasonic pain field. Subjects hit by this seem to exhibit disorientation, confusion, uncontrollable twitching, and sometimes seizures. Huge machines mounted on large vehicles produce wide enough swaths of ultrasonic waves that one shot can immobilize around thirty people from up to fifty yards away.
I've thought about carrying around earplugs, just in case someone goes rogue with these types of devices, but in most cases, this would only keep the blood in my ears from spilling out. None of these are reported to cause that kind of injury, but I'm sure it feels like it.
