The US State Department announced that it will be pulling more than half of its staff out of the American embassy in Havana, Cuba. This comes after reports of nearly 50 "attacks" on US and Canadian diplomats who are reporting symptoms similar to those exposed to the sound waves created by LRAD (long-range acoustic device) technology. These symptoms are similar those associated with a concussion, including headaches and nausea. LRAD exposure, however, can also leave people's ears ringing for several days after.
While no person or group has been found to be responsible for these attacks, there is no shortage of speculation among news outlets as to who would do such a thing and what their motivation might be. The mysterious device in question, on the other hand, has come under less scrutiny.
While the symptoms reported by victims match those of people who have been down-range of an LRAD, the victims' experiences are not quite the same. In this article, I'm going to outline the basics of LRAD technology along with the common form factors LRADs.
What Is LRAD and How Does It Work?
Long range acoustic device or LRAD is a term coined by the LRAD Corporation, which developed the technology after the attack on the USS Cole in 2000. They are also called "sound cannons" or acoustic hailing devices. They are able to broadcast sound at much longer distances than traditional loudspeakers.
LRADs use an array of piezoelectric transducers to function. This means that they take electricity and transform it into sound by changing shape incredibly rapidly. Learn more about how piezoelectric materials change shape and produce sound in our technical article on piezoelectric speakers.
The sound produced by LRADs isn't just loud—it's also exceptionally easy to direct in a narrow beam. This makes it useful for myriad applications where sound can be used with precision.
A diagram made by the LRAD Corporation showing the decibel levels of common sounds (red sounds can cause hearing loss)
Applications of LRADs
Of course, their most publicized application is dispersing crowds of protestors by emitting high-frequency sound waves at high volumes. This is where the term "sonic weapon" comes from. Although the technology has been around for over a decade, the first recorded use of an LRAD being used to disperse a crowd of protestors was at the G20 Summit in Pittsburgh back in 2009. You can see a video of the LRAD being used on protestors in the video below.
(Warning: Make sure to turn the volume down if you're wearing headphones. Even a recording of an LRAD in use could hurt your ears.)
Since 2003, LRADs have also been used as defense systems for Navy, commercial, and cargo vessels. Time and time again, the devices make headlines when used to defend ships from pirates, sometimes by blasting music like Britney Spears at aggressors.
According to LRAD Corporation's website, these devices aren't always used as ways to "weaponize" sound (indeed, they bold and underline the part in their fact sheet stating that "LRAD is not a weapon"). LRADs have a wide array of uses, most commonly broadcasting warnings and vital information during emergencies when communication is down and deterring wildlife from airport runways, solar and wind farms, nuclear power plants, and agricultural operations.
How Small Can an LRAD Be?
Although the victims in the US embassy have reported symptoms similar to LRAD exposure, there is evidence pointing toward the device not being one of the LRAD Corporation's models. There are two pieces of evidence pointing to this conclusion:
- The LRAD Corporation's models are fairly large and are usually mounted on a vehicle or tower, so they would not be easy to smuggle into a secure embassy. Smaller models can be disassembled and placed into cases, but most embassies search mysterious cases before allowing somebody to take one onto the premises.
- LRADs are incredibly loud but there have been no reports of unusually loud noises in the areas surrounding the embassy. Even the smaller models have a range of about a mile, so it's highly unlikely that an LRAD was used even on embassy grounds that could not be heard by the surrounding blocks.
Some LRAD models, like the LRAD 100X, are portable and can be carried easily while maintaining 137db SPL at 1 meter. Image courtesy of LRAD Corporation.
If an LRAD was used at the US embassy on diplomats, it would need to have a much shorter range to not draw attention from surrounding areas. This is where I could use some help from the AAC community. Is it possible for a device to put out 140 decibels but not be heard outside of a small area? And what kind of form factors could this hypothetical device be made into? Let me know what you think in the comments.
Author's note: Please keep your comments in the technical realm. I want to focus on whether a device that fits the story's description is theoretically possible, not speculate on who was behind the attacks or whether the attacks themselves were authentic.