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NYC Police use LRAD against protestors

LRAD: The Sound of Oppression

LRADs or Long-Range Acoustic Devices, are communications tools and non-lethal weapons that are employed by the military and militarized police forces the world over.


It is a bright day and the crowd around you is chanting various slogans against police violence.  You were careful and followed all the safety advice in preparation for this protest.  You came with friends, stuck together, had extra water, a fully charged cell phone, and knew your escape routes.  Suddenly, you are startled by what might just be the loudest voice you have ever heard coming from the front of the protests.  You can’t quite understand the words as they are simply too loud and distorted over the cries of the crowd.  You strain to see around the other protesters and their signs, but then the voice is replaced by a noise that sounds like the most obnoxious car alarm in existence, only a thousand times louder. Instinctively, you drop your sign and water bottle and cover your ears, but it does nothing to relieve the sound.  You begin to feel a strange
headache form in the front of your head.  Turning around, you realize that your friends are suffering as well.  You try to get their attention.  You want to tell them to leave, to go to the planned exit path, but you can’t seem to get your thoughts together.  It’s too loud to talk anyway.  The crowd swarms around you and as you feel the adrenaline rushing through you, you panic and run towards the nearest building.  As you cross behind the building and into the alley, the sound stops and you breath a sigh of relief.

This scenario and ones like it are being played out with increasing regularity on the streets of the United States as protests against police brutality and racism become more common. The tool used to create the overly loud voice and debilitating car alarm sound is known as an LRAD.

What is an LRAD?

LRADs or Long-Range Acoustic Devices, are communications tools and non-lethal weapons that are employed by the military and militarized police forces the world over.  They were originally developed by Delaware Corporation (now known as Genasys) for the US Department of Defense following the deadly attack on the USS Cole in Yemen on 12 October 2000.  The device emits a narrowly focused cone of sound that can reach up to 150 decibels (dB), far more than is necessary to cause permanent damage to humans and other creatures.  LRADs come in a variety of sizes ranging from large, ship mounted units used for long range communication over the water and to repel incoming boats to tiny units worn by police offers for street announcements and crowd control.  They have also been spotted mounted to MRAPs and on tripods.

How do LRADs work?

Some LRADs look like large flat disks while others, at first blush, look like normal megaphones. However, they don’t function like normal megaphones. Before we delve into how they work, though, let’s talk a bit about sound. Sound is a type of pressure wave moving through a medium, such as air. When the sound wave interacts with our bodies, generally through our ears, we can perceive it as sound. Because sound is a wave, multiple sound waves can interact with each other to distort and even cancel each other out. We see, or rather hear, this all the time in noise cancellation headphones where the opposite of the background noise surrounding the headset is mixed into the audio feed, effectively cancelling (or greatly reducing) the background noise and enabling the user to take a quiet nap, watch a movie, etc. without distraction. This technique can also be used to create perimeters to sound that prevent eavesdropping in a meeting or, in the case of LRADs, limit the effect of the device to a narrow cone.
The LRAD itself is constructed not from one moving part, such as the single driver of a megaphone, but rather from many tiny piezoelectric transducers. These transducers each produce the required sound and, much like how a crowd is louder than a single voice, combine to amplify the sound up to 150 dB. The outer ring of transducers, however, are kept out of phase with the inner transducers. As a result, the sounds mostly cancel each other out, leaving those outside of the cone of attack relatively unscathed while those within the cone end up disoriented or in pain.

Chart of LRAD audio levelsEvery LRAD product varient produces sound capable of causing pain and permanent damage.

How are LRADs used?

LRADs have two primary modes of use – communications & deterrence.   When used for communications, they are effectively loudspeakers that produce audio that is audible (though not necessarily clear) up to 75 meters (250 feet) away.  This can be effective in search and rescue operations, ship to ship communications, as well as and issuing warnings over the chants of protesters.  Deterrence mode is typically a warbling tone known as a reverse saw tooth.  If you have ever watched an episode of ‘Sea Shepherds’ on Discovery Channel, you might be familiar with the sound as it was commonly used as a weapon against the Sea Shepherds by the Japanese whaling ships.  This tone is annoying at lower volumes, much like a rogue car alarm, but is disruptive to humans at higher volumes. It can also be engaged at higher pitches in the 15kHz to 18Khz ranges.  These tones are on the very edge of human hearing, often only audible to younger people, but can still be damaging in high volumes.  People caught in the target zone of an LRAD have reported immediate disorientation, migraines, nausea, and anxiety as well as longer-term side effects that can last for weeks or are permanent.

What to do in during LRAD attack

  • Stay Calm
  • Get to Safety
  • Check for Injuries
  • Record Everything

If you are regularly out protesting you will very likely find yourself in the cone of attack of an LRAD sooner or later.  Understanding what to expect can make the difference between temporary discomfort or a lifetime of hearing loss.
Generally, in the United States, police are required to issue a warning about the use of LRADs before they switch them into deterrence mode.  If they are following these policies, you might hear them make an announcement over the LRAD.  If you do, don’t panic.  Alert your friends and make your way to the edge of the protest so that you can easily escape the sound if needed.  Begin recording the protest and, if possible, locate and capture the LRAD device on video.  Make sure that you and your friends always stay as far away as possible from the device.  LRADs are capable of rupturing human eardrums and causing permanent hearing loss at close range or under extended exposure.
If the police fail to issue an announcement or if you simply did not hear it, you might find yourself under assault from the device with no warning.  Again, don’t panic.  You will probably find yourself unable to easily piece together thoughts or sentences and the crowd around you will be in the same situation.  Gather your friends and try to move to the edge of the protest and out of the LRADs cone of attack.  Then, as soon as you are able, begin recording.

What to do after an LRAD attack

As mentioned earlier, LRADs have been proven to cause both temporary and long-term hearing loss.  If your group has been exposed to an LRAD, immediately check everyone for injuries once you have reached safety and document them.  In the following days and weeks, stay aware of your symptoms, keeping a log if necessary.  Rest your ears by staying away from loud sounds and, if possible, visit an Ear, Nose, and Throat specialist for a check-up.  Encourage the others in your group to do the same.

If you or someone in the protest has suffered an injury due to LRAD exposure, it is possible to file a lawsuit against the law enforcement agency and/or the city or county responsible.  Make sure that all evidence, including videos of the LRAD in use and any dB meter logs from before and after the LRAD activation, is kept safe on the cloud (preferably in multiple locations).  Be sure to gather the contact information of anyone who was injured or recording during event.  Check in with the ACLU, or other rights advocacy groups – they have had some success suing law enforcement for LRAD use.

In the United States, the right to peacefully assemble and petition the government for a redress of grievances is enshrined in the Constitution.  Moreover, the right for any people to take a stand against the systemic abuse of themselves or others is vital to maintaining a free society.  The militarization of the police in the United States along with the lack of accountability for those acting under the color of the law has made safe protesting a challenge.  Now more than ever, it is important to stay informed and aware of what you might encounter on the streets. Be responsible, be informed, and be safe.

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