Minnesota State Patrol uses long range acoustic device, first used by military, to disperse Maple Grove protesters
Dozens of protesters were detained Monday night after making a lot of noise outside a hotel where they believed the Border Patrol commander was staying.
Something troopers threatened to use to clear the crowd made a lot of ears perk up. It's called a "long range acoustic device," or LRAD.
Minnesota State Patrol troopers used a powerful sound system first used by the military in Maple Grove, Minnesota, to communicate and disperse noisy protesters.
"The LRAD is like a loudspeaker, but it focuses the sound in a narrow cone, so that if you're inside the cone, it's extremely loud," said retired Marine Colonel Mark Cancian, a senior adviser for the Center for Strategic and International Studies.
The Minnesota State Patrol says it has had an LRAD since 2013 and uses it to make sure "...entire groups can hear when an event is declared unlawful and they have been told to disperse."
During the Maple Grove protest, state patrol says officers checked the volume, issued dispersal notices, and did not use tones or sirens despite what has been reported on social media.
When it's cranked up, Cancian says, it can be overwhelming.
"We used it in Iraq when I was with the Marines. We tested it on the staff; they gave us the demonstration. If you're in the cone, it sounds like the voice of God is speaking to you," explained Cancian.
LRADs can project spoken commands at intense volumes or emit a loud, piercing tone designed to get attention and deter movement but Cancian says even spoken commands can have a powerful effect.
"I think we saw that in the video there of the system, because it's so loud, I mean, it pushes you back," said Cancian.
The system was designed as a less-lethal option to pepper spray, tear gas, and rubber bullets.
"In some situations where you might end up using force, kinetic force, or even lethal force, you know this can avoid that and avoid damage to permanent damage to people," said Cancian.
LRADs can be used as a sonic weapon and at full volume could cause pain, nausea, or hearing damage.
Police say they arrested 26 people for unlawful assembly and misdemeanor riot charges.