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Audio Engineers Built a Shield To Deflect Police Sound Cannons (vice.com)182
An anonymous reader quotes a report from Motherboard:Over the past two weeks, cops have been deploying every tool at their disposal to suppress worldwide protests and riots over the deaths of George Floyd, Breonna Taylor, Tony McDade, and other Black citizens killed by police. Since the protests began, demonstrators in multiple cities have reported spotting LRADs, or Long-Range Acoustic Devices, sonic weapons that blast sound waves at crowds over large distances and can cause permanent hearing loss. In response, two audio engineers from New York City have designed and built a shield which they say can block and even partially reflect these harmful sonic blasts back at the police. The shield's designers, Dave Rife and Gabe Liberti, were inspired to build the device after marching in the protests in New York City and hearing about LRAD sightings at demonstrations across the U.S.
"It's definitely been on our mind a lot how we've been seeing police instigating violence, and we've heard rumblings here and there about LRADs being spotted in NYC," said Rife, the shield's co-designer, who has previously worked in the architecture industry as an expert in acoustics. "We met on Sunday with the aim of building something that resembles a protest sign but can block a fair amount of sound energy. The idea is there could be a few of these in a car, driven to the location where someone has seen an LRAD, and then carried by hand from there." Rife and Liberti designed their shield to reflect audible sound waves that are condensed and carried via ultrasonic frequencies, and have tested it against a smaller and less powerful version of the LRAD that they built in their studio. It's made from a pine batten structure filled with recycled denim insulation, and covered by a half inch of clear acrylic on both sides, enabling the user to see ahead through a small window. According to a detailed teardown of the LRAD 300X posted by another audio technician, the LRADs produced by Genasys, the company that pioneered the devices, do not use an ultrasonic beam to project sound. However, Rife and Liberti say their design would still be effective against these hyper-directional blasts.
"It's definitely been on our mind a lot how we've been seeing police instigating violence, and we've heard rumblings here and there about LRADs being spotted in NYC," said Rife, the shield's co-designer, who has previously worked in the architecture industry as an expert in acoustics. "We met on Sunday with the aim of building something that resembles a protest sign but can block a fair amount of sound energy. The idea is there could be a few of these in a car, driven to the location where someone has seen an LRAD, and then carried by hand from there." Rife and Liberti designed their shield to reflect audible sound waves that are condensed and carried via ultrasonic frequencies, and have tested it against a smaller and less powerful version of the LRAD that they built in their studio. It's made from a pine batten structure filled with recycled denim insulation, and covered by a half inch of clear acrylic on both sides, enabling the user to see ahead through a small window. According to a detailed teardown of the LRAD 300X posted by another audio technician, the LRADs produced by Genasys, the company that pioneered the devices, do not use an ultrasonic beam to project sound. However, Rife and Liberti say their design would still be effective against these hyper-directional blasts.
