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

> 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

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).

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.

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.

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.

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.

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').

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.

This doesn't explain anything about what happened there.

Is a theoretical sonic weapon more likely than poisoning though?

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

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?

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.

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

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

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

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.

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.

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