
"Sonic attack" may have been two ultrasonic signals accidentally interfering - NicoJuicy
https://spectrum.ieee.org/semiconductors/devices/finally-a-likely-explanation-for-the-sonic-weapon-used-at-the-us-embassy-in-cuba
======
weinzierl
> 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-...](https://motherboard.vice.com/de/article/784z74/33c3--hacker-
zeigen-ihre-gadgets)

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

~~~
jerf
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...](http://ultrasonic-audio.com/acouspade-technical-
specification/) "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
> _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.

~~~
jerf
I would have thrown a bigger fuss if they didn't disappear as quickly as they
did. I assume other people threw a fuss for me, for which I thank them,
whoever they are.

The f'ing stupid thing is that _the checkout line is already one big ad_. It
advertises all the things that the stores have already figured out you're
likely to buy at the end of a shopping trip; candy, drinks, SD cards (dunno
why but it's pretty consistent), etc. It is the most effective possible ad,
since everything it is advertising is literally within arm's reach for
immediate purchase. You'd think that would be enough!

~~~
c22
I think the SD cards might be more about discouraging shoplifting of a small
easily liquidable good.

------
smoyer
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).

------
patcheudor
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](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.

~~~
walrus01
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)](https://en.wikipedia.org/wiki/The_Thing_\(listening_device\))

~~~
morsch
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.

~~~
IntronExon
That’s certainly possible, and in fact it could have been part of a routine
sweep for unpowered bugs that went wrong. It would also help to explain the
impressive range of bullshit “explanations” that keep getting printed. Mass
hysteria? Really?!

[https://www.theguardian.com/world/2017/oct/12/cuba-mass-
hyst...](https://www.theguardian.com/world/2017/oct/12/cuba-mass-hysteria-
sonic-attacks-neurologists)

Give me a break.

~~~
TeMPOraL
Did someone debunk the STD hypothesis? That sounded the most plausible to me
when first reported (didn't involve any conspiracy, just humans being humans -
plus was shameful enough to justify spinning stories about sonic attacks).

~~~
IntronExon
Well the info from the doctors who examined them debunks it, but that assumes
that as you say, it isn’t being spun. I think the truth is that we just don’t
know, and may never be in a position to know.

------
walrus01
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_
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?

~~~
walrus01
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.

~~~
achileas
Might have better luck with a PhD neuroscientist, but my guess (as a lowly MS)
would be that it's something we can't really experiment with because of
ethical issues, as you mentioned. While I studied the auditory system in grad
school, I wasn't until today aware of effects of RF on hearing, but there does
seem to be an effect at fairly high exposures:
[https://en.wikipedia.org/wiki/Microwave_auditory_effect](https://en.wikipedia.org/wiki/Microwave_auditory_effect)

~~~
walrus01
probably the closest we could get to studying it would be to emplace a lot of
instrumentation inside of a cadaver brain and focus the same power/frequency
of microwave at it. kind of a messy process since to duplicate real world
conditions you'd need to have the brain inside a skull...

~~~
achileas
Another issue is that you wouldn't have any sort of active responses that may
induce or attenuate any effects of the radiation. An example from the auditory
world is that for much of the history of auditory system research, it was
thought that the cochlea was a passive system (with a little more nuance, the
idea of an active cochlear mechanism was theorized but not confirmed). But
that was because the technological limitations of the time only allowed
experiments on dead cochleas (primarily by von Bekesy) - once otoacoustic
emissions were first recorded (70s or early 80s) we finally had verification
of the cochlear amplifier.

More, if interested:
[https://en.wikipedia.org/wiki/Cochlear_amplifier](https://en.wikipedia.org/wiki/Cochlear_amplifier)

------
varjag
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.

------
ggm
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.

~~~
walrus01
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.

~~~
ggm
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.

~~~
walrus01
sorry to dispel your theory: but the communications technology used by the DoS
to talk to LEO satellite is so low power that it's safe enough to use next to
your head. pretty much every embassy has a few Iridium phones on hand. An
external antenna (attached to a 50 ohm coaxial cable) on a roof, connected to
a docked iridium base station, has the same EIRP and rf parameters as the
built in antenna in an iridium handset. which are completely safe to use for
multi-hour periods in an active call held next to your head. an iridium
antenna is about half the size of a hockey puck and operates in a range from
1400-1600 MHz (you can use the same antenna for GPS Rx-only if you want).

The DoS puts a lot of effort into knowing what RF emissions are going on in
and around an embassy. For instance they're quite cautious with where and how
wifi access points can be deployed.

The DoS rarely if ever uses point to point microwave, and even if they did,
ptp microwave is completely safe to shoot from building to building. If you
live in a medium to large sized city the big-4 cellular carriers in the US
probably have at least several hundred PTP links in 6, 11, 18, 23 GHz and
other bands operating between rooftop sites right now.

~~~
ggm
If the DoS is so RF aware, why aren't they citing the RF meter evidence of
what was externally pointed at the site? I think the state department has
_guidelines_ , for sure. I also think their analysis of the specifics here are
either shrouded in secrecy, or absent. I tend to incompetence over malice.
Hence, absent, and probably internally sourced, or if externally sourced, less
an attack than an unexpected side effect of something else. (and, I did not
intend to imply LEO was a source of RF poison. More, that high RTT was a
consequence of GEO sat comms)

I actually subscribe to the _mass hysteria_ theory in this case. Again, with
no role to play and purely on what I read, I feel it is as plausible, and
equally simple as a cause. Nobody much likes it because hysteria is such a
loaded word, but I believe it because I frequently find myself falling into
placebo effect. Those aches and pains go away with paracetemol, when its
ability to heal those aches and pains is at best moot. The mind is strange.
The lesions, certainly are odd. Maybe there is a sub-culture of motley crue
headbanging inside state, and they share signs of too much metal?

~~~
walrus01
If there is any pervasive health problem going on inside the DoS, I would have
to guess alcohol abuse.

------
trdtaylor1
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
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...](https://gizmodo.com/some-ghosts-may-be-sound-waves-just-below-human-
heari-1737065693)

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

------
iamleppert
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.

------
mhb
This doesn't explain anything about what happened there.

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

~~~
dgacmu
Instead of the ieee summary, check the original paper:
[https://spqr.eecs.umich.edu/papers/YanFuXu-Cuba-CSE-
TR-001-1...](https://spqr.eecs.umich.edu/papers/YanFuXu-Cuba-CSE-
TR-001-18.pdf)

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

~~~
trdtaylor1
Just reading through that, the unanswered questions are literally the same
questions asked before the research began.

------
RobLach
Is a theoretical sonic weapon more likely than poisoning though?

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

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

------
adamzk
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?

------
tritium
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.

------
em3rgent0rdr
"Never attribute to malice that which is adequately explained by stupidity."

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

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

------
sova
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.

------
joshuaheard
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
How do you make an audio recording of a hallucination?

~~~
joshuaheard
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.

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

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

