"Sonic attack" may have been two ultrasonic signals accidentally interfering

https://spectrum.ieee.org/semiconductors/devices/finally-a-likely-explanation-for-the-sonic-weapon-used-at-the-us-embassy-in-cuba

by NicoJuicy • 8 years ago

170 71 8 years ago

spectrum.ieee.org

mhb• 8 years ago

This doesn't explain anything about what happened there.

alsoconfuzed• 8 years ago

Subharmonics? Additive waves? What was the source and why?

dgacmu• 8 years ago

Instead of the ieee summary, check the original paper: https://spqr.eecs.umich.edu/papers/YanFuXu-Cuba-CSE-TR-001-1...

It's better and more careful not to over claim.

beautifulfreak• 8 years ago

Their paper doesn't identify where the signals came from. "The emitter source remains an open question, but could range from covert ultrasonic exfiltration of modulated data to ultrasonic jammers of eavesdropping devices or perhaps just ultrasonic pest repellents. It’s also possible that someone was trying to covertly deliver data into a localized space using ultrasound to say, activate a sensor or other hidden device."

trdtaylor12• 8 years ago

So the researchers are proposing the U.S. Embassy in Cuba has brain-altering levels of noise in the ultrasonic region somehow caused by two or more simple,low level and possibly common ultrasonic emitters without malicious intent...

Xu's other recent works has been lacking meat and are better at fear-mongering (Tesla ultrasonic 'hack', Smart grid 'hack').

iaw• 8 years ago

The researchers describe a mode of malfunction where the interference patterns of two separate audio sources can create the same audible effects recorded in Cuba.

The course of reasoning I see proposed is:

-> Personnel in Cuba received an odd class of injury

-> High frequency sound can cause this class of injury and seems the most likely candidate

-> HF sound doesn't propagate well in air and has many other properties that make it a poor tool for espionage/malicious actions

-> Xu's work demonstrates that sound interference from two HF sources can create unexpected effects due to non-linearities in the physics behind sound/air

Xu's work is the last piece in the puzzle IMO. It offers a plausible scenario: the building had Cuban tech and when we moved in we installed non-Cuban tech that, due to some benign like motor speeds, creates sonic problems for building occupants. The reason this doesn't really happen anywhere else is because of the unique situation surrounding the building.

The next steps I'd take were I investigating this is to look at what equipment was installed at the facilities and then determine what frequencies the equipment operates to try to find a likely candidate.

Edit: I realized you may not be familiar with equipment noise problems, these two articles described problems in the infrasound range.

[0] https://gizmodo.com/some-ghosts-may-be-sound-waves-just-belo...

[1] https://www.theguardian.com/science/2003/oct/16/science.faro...

neves• 8 years ago

Ok, but who has ultrasonic emitters around? Were it America own spionage gadgets?

fspeech• 8 years ago

Reading the article, it seems that they are trying to explain the sound recording posted on the internet. They are not privy to any other data and it is just speculation on how this may relate to symptoms reported by the diplomats.

mmaunder• 8 years ago

They just explained what anyone who has played with 2 sine waves already knows, and drew no conclusions.

superkuh• 8 years ago

And even beyond that, ultrasound interference to produce restricted audio volumes has been commercialized and used in places like museums for decades.

RobLach• 8 years ago

Is a theoretical sonic weapon more likely than poisoning though?

tytytytytytytyt• 8 years ago

I think NPR had someone saying the symptoms all pointed towards people being poisoned by chemotherapy drugs.

varjag• 8 years ago

The two "accidental" intermodulating devices still have to emit the levels of energy sufficient to damage brain tissue. We're not talking room occupancy sensor levels, more like industrial ultrasonic washer levels.

tritium• 8 years ago

But... brain damage?

The level of energy at work, required to cause harm like that would have to operate on the level of two sonar pings from hell, fortunitously converging to form a node with appropriate geometry to harm a watermelon-sized organ.

We know that blasts from high explosives can transmit brain damaging pressure waves through durable vehicular armor, and there aren’t many other sources of energy known to send opportunistic signals through mediums, quite like that.

If I needed to surreptitiously send an accoustic message to an audience positioned at a distance, I might need to use a very powerful source, with a locally inaudible signal that only incidentally becomes audible when crossing other signals, but...

Such a transmission would probably only be effective up to the horizon, and require line-of-sight reception. Provided that the distance for line-of-sight access up to the horizon is about 25-ish miles, depending on topography, and the loudness required for that kind of reach, generating two beams (as powerful as noises produced by attenuated explosive blast waves) seems like it would require some pretty heavy equipment. Like room-sized equipment.

Think about what it takes to push a sound wave several miles, like a ripple across a pond, and what that sounds like up close. Race tracks, rock concerts, passenger jets. These things all readily occupy a three meter cube, at least. Not to mention that the fidelity of such loud noised is very low, and blurred by the intervening air, the further away you get, meaning any digital packet-based transmission would require really coarse, slow bandwidth.

That rules out a lot of sneaky carry-on luggage sized equipment, for generating such signals. Which points, maybe, to no less than two off-site phased-array tone generators forming crossed noise beams for receipt by someone.

Still a lot of mystery to suss out, and a lot of gray areas to speculate upon. And I’m tossing a lot of assumptions into the mix, like whether there was deliberate intent at all, and whether side effects were emergent or not. And while there’d be limits and ceilings based on line of sight, that doesn’t rule out scale of equipment or range of activity.

The only takeaway is that brain damage at a distance requires a lot of intense energy, usually explosive, although deleterious explosive energy and associated noise can scale from sizes relative to something as small as fire crackers and .22L rounds on up.

patcheudor• 8 years ago

Errant high-power microwave signals still seem to be the #1 likely scenario in my book. It was covered here previously:

https://news.ycombinator.com/item?id=15332122

While I tossed out the idea in that thread that it could be related to pest control, I think the most likely explanation would be an improperly aimed high-powered microwave antenna. I can't imagine any ultrasonic signal being at such a power level as to cause physical damage at a distance, let alone through walls. In fact, I'm not sure that's ever been shown to be possible. We know for a fact; however, that high powered microwaves can be highly damaging and in combination with the microwave auditory effect, would explain it quite well.

walrus018• 8 years ago

high power microwave/millimeter wave can also be focused pretty tightly, down to 1.5 degrees central beam width... Telecom grade point to point millimeter wave stuff (71-86 GHz) can be +19 dBm into a 52dBi gain 60cm antenna. But if you're not actually trying to communicate and just want to flood the spectrum with shit at high powers, it's totally feasible to build something that has a power of like +30 fed into a 56dBi gain directional parabolic antenna.

one possible explanation is that they were trying to do a more "modern" version of the famous battery-free bug that was found in the US moscow embassy, where the listening apparatus and its transmitter were powered passively by receiving RF:

https://en.wikipedia.org/wiki/The_Thing_(listening_device)

morsch• 8 years ago

Who's they? Absent other evidence, it seems to me the most likely people to be emitting microwaves at an American embassy would be... Americans.

IntronExon4• 8 years ago

You could also get unexpected results using two beams of microwaves which constructively interfere. A simple misalignment could shift the intersection and lead to cooked noodles. Microwaves are as capable of that as sound waves, and more likely to be generated by relatively compact devices, while causing brain damage and auditory effects. I can also imagine that it’s the kind of “sources and methods” talk our government doesn’t appreciate.

walrus018• 8 years ago

microwave/RF engineer here: I have seen speculation from people with 25+ years experience in my field that what was being experienced was not acoustic at all, but was some sort of SIGINT apparatus gone wrong, or millimeter wave at very high power and focused. Very curious what the results would have been if the US had carried a 4 to 120 GHz capable portable spectrum analyzer and set of horn antennas in a diplomatic bag to the locations where this was experienced, and done thorough scans of various power levels/frequencies in the millimeter wave frequencies.

quick edit: the weird part here is that DoS (department of state) has an entire division of people who specialize in TSCM (technical surveillance countermeasures). I would be surprised if most embassies did not have RF detection apparatus capable of up to the high millimeter wave frequencies on hand. These things are pretty pricey, $20,000 or so for a full setup, but compared to the anti-bugging budget of the DoS as a whole it's a tiny drop in the bucket.

_greim_• 8 years ago

Not an expert at all, just curious; could this kind of radiation have caused the high-pitched sounds, or perception of sounds, as purely a side effect?

walrus018• 8 years ago

not the RF itself, no, but the effect of high powered millimeter-waves focused at a person's head could very possible have that effect on a neurological basis. It's not the sort of thing that has ever been voluntarily tested on humans (for obvious reasons), and if tested on animals, animals can't tell you if they're observing auditory hallucinations...

Though the science behind avoiding high RF exposure is known and observed (ex: tower climbers don't want to hang around on the front side of a large sector antenna with high EIRP in the 2.5 GHz band).

Would have to ask a MD that specializes in the brain.

jonstewart• 8 years ago

I'm not sure I'd call it "likely", since the researchers disclaim any physiological effects.

dogruck• 8 years ago

Has the supposed sonic weapon, and its effect been confirmed? Link to best unbiased news story?

smoyer3• 8 years ago

There are two key phrases in this article "intermodulation distortion" and "when signal processing equipment behaves in a nonlinear way". While there is not a concrete description of the signals that might have been present in the building, I completely understand how these non-linearities can cause havoc.

I previously spent almost 30 years in the cable television industry and the transmission of broadband signals requires linear amplification over almost three magnitudes. The two main distortions we worry about are Composite Second Order and Composite Triple Beat. This distortion represents all the permutations of sums and differences of two and three signals respectively.

In narrow band communications, we amplify the signal and then filter out everything except the desired signal. In wide-band electronics, these products of distortion will often fall on top of other signals you're sending. The only way to succeed is to create very, very linear amplifiers (usually by burning a huge amount of bias current relative to the signal power).

weinzierl• 8 years ago

Yan was even able to embed an ultrasonic version of the Rick Astley song “Never Gonna Give You Up,” which became audible at the point where the two signals crossed.

At 33C3 I rode an escalator when I suddenly heard "Never Gonna Give You Up" but apparently no one else did. It was over after a few seconds. At the top of escalator there was a guy pointing a directional speaker at random people.

Only reference I could find is in German, but it has a picture [1]. The story says the guy on the picture is not the inventor of the device.

EDIT: The thing is a parametric ultrasonic speaker and the design files and software are on GitHub [2].

[1] https://motherboard.vice.com/de/article/784z74/33c3--hacker-...

[2] https://github.com/niklasfauth/parametricspeaker

smoyer3• 8 years ago

I NEED to buy one of these immediately! (at various points my two oldest kids have rick-rolled me and it's pay-back time).

bigiain• 8 years ago

You can build one yourself if you want:

https://hackaday.io/project/9085-ultrasonic-directional-spea...

Its reasonably well known tech in the maker community these days... I first saw one demoed at a Dorkbot meeting 10 years or so ago.

jerf3• 8 years ago

It's actually off-the-shelf tech now. I've been in a number of supermarkets where they use this to beam ads at you while standing in line for the checkout. (All of which have since stopped doing it, for what it's worth. YMMV.)

There was some hope for a while that this might turn out to be a way to hack sound so that you could produce a flat speaker full of those tiny ultrasonic speakers, and then use non-linear interference to produce deep, booming bass sounds, without having to have the much-larger speakers you need today for that to work correctly. Unfortunately, either nobody could crack the technique, or it's simply impossible, because the real speakers that emerged are quite tinny. Here's a commercial offering, where they're only willing to promise down to 150Hz in the text: http://ultrasonic-audio.com/acouspade-technical-specificatio... "The sound is of high-quality, with low noise and great frequency response, which includes authentic reproduction of bass notes and frequencies as low as 150 Hz." Which, if accurate, is better than the speakers I've heard, but still a long ways from "thumping bass" coming out of a square that could be hung on the wall as casually as a picture frame.

eveningcoffee• 8 years ago

I've been in a number of supermarkets where they use this to beam ads at you while standing in line for the checkout.

This is more than creepy. It should be made illegal along with using cameras for anything else than security.

amelius• 8 years ago

You could produce that deep bass if you knew exactly where the listeners are. Throwing some computer vision/ML in the mix could solve the problem.

PS: It can't be patented now, cause I mentioned it on HN first :)

ashleyn• 8 years ago

I remember reading about this in Popular Science when I was eleven years old. They compared it to the difference between laser light and conventional light.

quickthrower2• 8 years ago

"Never attribute to stupidity that which is adequately explained by malice."

mads2• 8 years ago

I had a Yamaha soundbar some years ago, which could be calibrated via a small microphone, that you would place in the location in the room, where you wanted the sound to be beamed. During calibration it would create some beeping and whooping sounds, I guess to learn about the room it was in and you could then sort of have a sound bubble in your sofa, when watching a movie late at night.

asclepi• 8 years ago

That sounds pretty similar to Sonos Trueplay: https://www.youtube.com/watch?v=8QgJHUy93T0&t=138s

joshuaheard2• 8 years ago

I read another article describing what doctors concluded after examining the symptoms, which was it was likely poison, as no acoustic effect could have produced those symptoms. They believed the noise complaints were actually a resulting effect of the poison. My guess is a heavy-handed pest control technician.

wil421• 8 years ago

How do you make an audio recording of a hallucination?

joshuaheard2• 8 years ago

You're assuming the audio recording is causing the symptoms, which the authors disclaim. The noise could be real, but the symptoms caused by another vector.

adamzk• 8 years ago

I think depending on the size and shape of the region of constructive interference it's possible to apply force selectively to somebody's head. In my old apartment, one of the cabinet doors in the kitchen would rattle when the music in the living room played a certain note. Putting my hand in that area I could feel the force of it and it had fairly discreet boundaries in all 3 dimensions. I can imagine it would cause quite a headache if that were suddenly applied directly to my brain. And that's just from my stereo. Work a moving source with broader range, it's theoretically possible to"sweep" an area for susceptible targets. When the source is outside the audible range it would could be largely unnoticeable. Selectively applying pressure to certain parts of the brain can cause a range of symptoms. Like if all of a sudden somebody squeezed your pituitary gland how would you feel?

iamleppert• 8 years ago

There was an article published awhile back that seemed to indicate the noises people heard (and still here) are due to tinatus and speculated they were poisoned with one of the many prescription medications that can cause tinatus. I can’t remember if they had any clinical testing but it seems a lot more plausible than some kind of sonic attack.

As someone who recently started suffering from mild tinatus I can assure you it’s a very bizarre sensation. If I didn’t know better I’d assume I was the victim of some kind of attack on my hearing as well.

ggm3• 8 years ago

Is it not equally likely that the source of high intensity, high frequency RF modulation lies inside the US communications infrastructure associated with an Embassy inside a declared enemy state? I.E. the reason there is no external source, is that it was a product of faulty US SIGINT in the first place.

Is Guantanamo Bay reachable by microwave link from Havana? Day traders prefer RF to complex internet routes, if they can show speed advantages. Direct RF might have some SIGINT advantage over other choices here, to talk between US assets in the economy.

I'm not a cuban or a russian, and nobody pays me for my opinions btw. I just find it strange everyone externalises the source, when we probably all believe the investment the US makes inside its own communications is actually sufficiently at scale to be the source of the problem.

walrus018• 8 years ago

the people who experienced this, many of them lived outside of the embassy compound.

and no, havana and guantanamo are way too far apart for line of sight microwave. really doubt that the US and Canadians accidentally did this to themselves.

i am actually somewhat familiar with the technology the US uses for two way satellite earth stations on the roof of latin american embassies (for a telecom link that can't be easily cut off by the host nation-state). the other end of some of those links is on the roof of a major internet IX point in miami. the people at the DoS who are responsible for two way satellite and microwave stuff would have no cause to aim a roof mounted antenna anywhere other than at the sky, at a geostationary satellite.

the weird thing about this is that microwave and millimeter wave really does not go through matter (walls, windows, wood, brick, concrete, etc) very well at all above 5 GHz. At very high frequencies you need an extremely focused antenna and very high transmit power to possibly affect peoples' heads while they are asleep in their bedroom.

ggm3• 8 years ago

The people who experienced this, may have lived outside the embassy compound, but they presumably worked inside the embassy compound.

Why do you really doubt they did this to themselves? On what basis do we automatically assume an external agency did this to them? Thats the underpinning argument I'm running.

Since you are familiar with the technology, you have a basis to believe, but the rest of us, have none. You just said the comms are sat based, homed in Miami. So, unless there is a LEO component, this means secure channel dialogue incurs a minimum Geo orbit RTT. Well, maybe thats the price you pay.

sova• 8 years ago

Wow that's actually really quite relieving news. I heard a recording of the clip and afterward read that people experienced some brain damage (!) luckily the ultrasonic waves aren't replicable through my headphones. I don't recommend listening anyway, it's not pleasant and does sound like interference.

em3rgent0rdr• 8 years ago

"Never attribute to malice that which is adequately explained by stupidity."

dwighttk• 8 years ago

Unless I'm missing something this is a possible explanation for the sound heard during the alleged attacks, but not for the symptoms experienced.

"Sonic attack" may have been two ultrasonic signals accidentally interfering

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