How sound can be used as a weapon

Anyone who has sobbed over a sad song knows sound can move us. But not just emotionally; sound can move us physically as well.

Military and law enforcement agencies scare off attackers, intruders and protestors with a piece of technology called the LRAD, short for long-range acoustic device. This contraption, which is like a car alarm on steroids, emits sounds so painful to hear that they send people running in the opposite direction to escape them. It was used for the first time by a U.S. police department in 2009 in Pittsburg to break up protesters.

The company that makes these devices also says they could be used to build invisible fences at the border to dissuade undocumented immigrants from crossing and to protect ships at sea from pirates. It could steer flocks of birds away from turbines at wind farms (to protect the birds) and away from planes (to protect humans). Avian crashes into airplanes happen more often than you might realize, sometimes with disastrous consequences. In 2013, more than 11,000 bird strikes were reported, according to the U.S. Federal Aviation Administration.

This kind of technology has been around since the mid-2000s. In the future, technologists will also be using sound to exert actual physical forces on objects.

Just last week, scientists published a paper in which they described how to float objects using sound holograms. Scientists created tweezer- and bottle-shaped sounds waves that could actually “hold” tiny styrofoam spheres in mid-air. Researchers hope they to perfect these holo-holders to use them to target medications to specific organs or tumors. We, meanwhile, hope it could one day give us X-Man Banshee powers.

A version of this piece was presented on November 7, 2015 at the Real Future of Sound at our Real Future Fair in San Francisco.

Daniela Hernandez is a senior writer at Fusion. She likes science, robots, pugs, and coffee.