LRAD Technology 101 (and How It Relates to US Diplomats in Cuba)

October 07, 2017 by Tim Youngblood

The United States is pulling more diplomats out of Cuba after more reports of symptoms similar to those exposed to "sonic attacks."

The United States is pulling more diplomats out of Cuba after more reports of symptoms similar to those exposed to "sonic attacks."

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:

  1. 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. 
  2. 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.

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    philba October 12, 2017

    What are the frequency limits of LRAD?  I would expect higher frequencies to attenuate more quickly than lower. Is that true? Or is it possible to have ultrasonic LRAD? Perhaps that what is going on in Cuba.

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    • tim yb October 13, 2017
      I looked at the datasheets for some of their devices ( and they didn't list any frequency limits :( From what I've read about LRADs, the sound needs to be audible in order to cause discomfort. So as far as I can tell, an ultrasonic LRAD would not work.
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    RickB_Nashville October 13, 2017

    1. on why loud noise hasn’t been reported - seems it could be either outside the range of hearing (ultrasonic) or extremely brief so it’s over by the time a sleeping victim is awake enough to recognize he’s heard something. (Reminds me of the earthquake a few years ago that was centered near St. Louis. In Nashville, many people heard a very brief but loud crashing sound. But speaking for myself and a few other people I spoke with afterwards, we just found ourselves awake and vaguely aware we’d heard something, but not sure what it sounded like or even if we might have dreamed it.
    2. How to concentrate it: the LRAD is trying to hit a moving person (and not to severely injure them) so it would be set up to produce a broad beam of sound. A hypothetical weapon could concentrate sound on a focal point, so it might be very loud only at that focal point and in the hourglass shaped volume along the line from the emitter to the target. An analogy would be the use of a large magnifier to burn paper by concentrating sunlight. The energy at the focal point is far higher than anywhere else in the system (except for the Sun of course). If this is the principle at play, then it adds another rationale for the attacks happening at night: the victim is staying still, so there’s time to focus on that spot.

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