Examining overlooked clues reveals how ultrasound could have caused harm in Cuba
spectrum.ieee.org
spectrum.ieee.org
2. They cannot claim they discovered interference that shifts frequency.
3. They cannot claim to have "Reverse engineered the Cuban "Sonic Weapon" attack"
They instead PROPOSE 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 and THAT'S why some people can hear it...
Xu's other recent works has been lacking meat and are better at fear-mongering (Tesla ultrasonic 'hack', Smart grid 'hack').
Xu's ultrasonic Tesla 'hack' showed how dangerous the pedestrian avoidance system was by wrapping one of her graduate students in Michelin Man-sized ultrasonic dampening material. Tesla had to make an uncharacteristically brusque comment stating they couldn't reproduce anything of risk to Tesla drivers in the world.
She is the equivalent of the National Enquirer in the security research world and steadily increased her ability to clickbait.
And the 155dB number cited by the Canadian government would require considerable (hundreds of watts) of power to produce at close range.
This whole case defies logic. The early reports were of mysterious symptoms not associated with any obvious exposure. Once ultrasound/infrasound began being mentioned, people began reporting hearing mysterious sounds.
The recording makes even less sense: If the sound levels were really sufficient to cause physical trauma, surely they would overwhelm the phone's microphone?
I don't understand this comment. Are you implying that a low-pass filter would shift the frequencies of part of the signal rather than (mostly) filtering some of the frequencies away...?
I may be wrong but I think a filter would have the same effect in this case.
My point is that any number of inputs could produce the observation, so their claim of reverse engineering is rather questionable. In fact they have no evidence of ultrasound at all.
> In the most common application, two signals at frequencies f1 and f2 are mixed, creating two new signals, one at the sum f1 + f2 of the two frequencies, and the other at the difference f1 − f2.
Then the low pass filter is used to remove the original signals and the sum, leaving only the difference.
I know, it's confusing ...
Since commenters here are objecting to the article title as misleading, we've replaced it with the subtitle (with s/Havana/Cuba/ to fit in 80 chars).
Until we start putting high order low pass filters in everything.
I believe the intent was to say:
A) We have recording from Cuba, therefore there's proof of ultrasonic noise.
B) This noise we have is in the audible spectrum, but we have reason to suspect it's from the interaction of two ultrasonic frequencies that together produce a very whiney audible frequency
C) Ultrasonic noise can be used for spying and voice-injection, so there's a potential motive for the US to use such technology at an embassy.
At about 36m you can hear the rumbling IMD effects.
So cool. I had this idea a long time ago but never approached it. Kudos to them for some follow through.
Edit: this is, of course, a rhetorical question. The "reverse-engineered weapon" claim is clearly false.
>> While the math leads us to believe that intermodulation distortion is a likely culprit in the Cuban case, we haven’t ruled out other null hypotheses that may account for the discomfort that diplomats felt. For example, maybe the tones people heard didn’t cause their symptoms but were just another symptom, a clue to the real cause.
Unless what I read was just plain lies, I don't see how this is plausible. Just reading The Guardian's article [1] I see no room for other plausible explanations in every case... remember there were at least 21 US victims (!!):
The blaring, grinding noise jolted the American diplomat from his bed in a Havana hotel. He moved just a few feet, and there was silence. He climbed back into bed. Inexplicably, the agonizing sound hit him again. It was as if he’d walked through some invisible wall cutting straight through his room.
Soon came the hearing loss, and the speech problems, symptoms both similar and altogether different from others among at least 21 US victims in an astonishing international mystery still unfolding in Cuba. The top US diplomat has called them “health attacks”.
New details learned by the Associated Press indicate at least some of the incidents were confined to specific rooms or even parts of rooms with laser-like specificity, baffling US officials who say the facts and the physics don’t add up.
[1] https://www.theguardian.com/world/2017/sep/14/mystery-of-son...
Note that the purpose of the microwaves doesn't have to be frying someone's brain or creating sound; it can be some unrelated attempt to e.g. try to intercept data think about possible attempts to use preexisting materials in a way similar to https://en.wikipedia.org/wiki/The_Thing_(listening_device)
Maybe they perceived sound because the right nerves or neurons were stimulated.
They've done impressive work figuring out why the "ultrasonic" attack would have an audible component. They can now reproduce the tones heard in Cuba using an ultrasonic source, something that didn't make sense before. Responsibly, they never claim that the "ultrasonic attack" is conclusively responsible for the actual harm, although it appears likely.
So given that there is no convincing reason to believe ultrasound has anything to do with it, they've now demonstrated a way to make audible noise as a consequence of interaction between two ultrasonic sources. They chose this particular (obscure) way of getting audible sound from an ultrasound emitter because a journalist sent a video of a sound whose relevance is that it was recorded on Cuba.
And the great result is that now you need at least two ultrasound emitters, one of which is a bulky 155 dB emitter just lying around undetected in the homes of American diplomats. I don't see how the explanation of a minor problem with the ultrasound theory is any great advance.
All of this is obvious though; you aren't being rational about this, like you have a dog in the race.
The authors themselves admit that their design and hypothetical weapon cannot account for the actual symptoms.
Edit: when my kids finally convince me to get a dog for the family, I'll name it Truth, Facts, or Parmenides.