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Matchstick-Sized Sensor Can Record Your Private Chats Outdoors
wabrandsma sends this story from New Scientist:
"A sensor previously used for military operations can now be tuned to secretly locate and record any single conversation on a busy street. [A] Dutch acoustics firm, Microflown Technologies, has developed a matchstick-sized sensor that can pinpoint and record a target's conversations from a distance. Known as an acoustic vector sensor, Microflown's sensor measures the movement of air, disturbed by sound waves, to almost instantly locate where a sound originated. It can then identify the noise and, if required, transmit it live to waiting ears. Security technologist Bruce Schneier says this new capability is unwelcome – particularly given the recent claims about the NSA's success at tapping into our private lives. 'It's not just this one technology that's the problem,' Schneier says. 'It's the mic plus the drones, plus the signal processing, plus voice recognition.'"
Gene Hackman was doing this in the 1970's http://www.imdb.com/title/tt0071360/?ref_=sr_1
Only the State obtains its revenue by coercion. - Murray Rothbard
I can imagine the same people collecting all of our online data now adding offline conversations to it. Imagine adding this to an insect sized flying drone and releasing many of them into your city. The could go anywhere and record anything.
While the sensor measures the vector direction of sound, it measures the *SUM* of all sounds impinging on that point. With a single point sensor, you can't separate the direction of a particular one.
Now, a reasonably small array of these sensors (maybe as small as 30cm across) might be able to accurately localize the source, in the same way that your brain can tell what direction a sound is coming from with just two ears.
Of course, it will also be confused by multipath and reflections, although if adequately characterized, those could be used for localization as well, since the reflected paths have different spectral properties.
There are LOTS of sensors that are tiny and easily deployed these days, using all sorts of sensing modalities. And processor horsepower and tiny comm to get the signals to the processor are easier to get too.
Governments have always had the technical means to be invasive, they are restrained by common decency and the law of the land. I actually would have more concerns about private industry: they're not subject to most privacy laws (at least in the U.S.): The wiretap laws, for instance, refer only to comms over a system. If you want to set up a big acoustic array at the beach and record everyone's conversations, process it, and sell the product to whoever, that's perfectly legal. Or set that array up out on the pubic street in front of your house, or the thermal imaging camera, or the mmWave wall penetrating radar or whatever.
So, it's those laws and common decency is where the efforts should concentrate.
I usually agree with Bruce. But unless that quote was taken way out of context, he is wrong here. Technology isn't the problem. It never is. It is the people salivating at the thought of using it against us. Even those who think they are doing us a service to keep us safe: when they invade our privacy, they are the problem. The tech? It's actually cool. There are probably - how would someone jaded to the world of sound and copyright put it - many non-infringing uses of the tech. It can probably even be used in a way that isn't spying. For example recording a conference speaker (with permission) in a noisy room or the like.
...everybody has it. The last thing we need is awesome tech only spies and generals possess (weapons of mass destruction/contamination being a notable exception). So yes, this is unwelcome technology, but since it's already there, we might as well let everybody have it.
Governments have always had the technical means to be invasive, they are restrained by common decency and the law of the land.
What governments would those be which are restrained by the law, let alone common decency?
"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety."
And budget. Monitoring people used to require paying someone to listen to the tapes. The advent of computers has greatly brought down the cost of mass-monitoring by allowing the computers to sift through the vast collection and just flag the potentially interesting things for human examination.
I think the coarse hair would block the sound waves on a pubic street, thus rendering the technology useless.
Governments have always had the technical means to be invasive, they are restrained by common decency and the law of the land.
They are?
If you want to set up a big acoustic array at the beach
Were I to surveil the beach, I'd be more interested in visual than auditory information. YMMV.
All joking aside, I'm skeptical of the technical claims of superiority, other than small size. That's tempered by my lack of knowledge of acoustics. I think of it in terms of analogies to optics or radar (as a physicist I once knew said, a wave is a wave is a wave). You need an array to locate the direction something is coming from. Roughly speaking the larger the array relative to the wavelength, the more precisely you can determine direction, and the more you can spatially filter that source from other sources. You can do that with small optical sensors (e.g. a camera or your eye) only because of the short wavelength of light. Radar antennas with the same directionality and resolution need to be much larger. At 1kHz (a frequency you definitely need to understand conversation) the wavelength of a sound wave is 343mm. For radio waves that's the wavelength you'd get at 875MHz. You need a fairly big antenna to get decent resolution. That can be accomplished by widely spaced sensors (antenna elements, whatever) and some serious signal processing. I don't see how one of these sensors can have any serious directionality by itself, or having three in the same place pointing at x, y and z directions can do much.
One difference I can think of between electromagnetic radiation and sound waves is that the former are transverse waves and the latter are longitudinal waves. Does that make much of a difference for these purposes?
That wouldn't be a problem on Brazilian streets.
Note to old school eavesdroppers: don't get rid of all your parabolic dish microphones just yet.
I deny that I have not avoided attaining the opposite of that which I do not want.
multipath and reflections
are already used in DSP to model rooms and sometimes even to reconstruct 3D shape from sound alone
Who logs in to gdm? Not I, said the duck.
... If you want to set up a big acoustic array at the beach and record everyone's conversations, process it, and sell the product to whoever, that's perfectly legal...
Unless you are openly and obviously (to the subjects being recorded) voice recording, most states don't allow the type of action you posit there. At least ONE party from each conversation has to consent to any recording and in 12 states EVERYONE must consent. There are limited "Presumed Consent" exceptions but a public beach would not be one of them. There is a quick review here:
http://www.wingfieldaudio.com/surreptitious-recording.html
Not sure about "through the walls" video/audio recording but I'd bet peeping tom laws would be made to suffice...
You have the right to remain sentient. If you give up the right to remain sentient, you will be elected to public office
That's true for a single snapshot of sound in any given instant. But if you collecting acoustic data over a period of time, transient sounds (noise) average out, and the loud peak (gunshot) or cyclical nature (engine) of certain sounds of interest should ease their extraction, with sufficient processing.
That was my impression too (one of my grad school courses was on acoustics and sonar design). That's what they do in submarines - make a great big phased array microphone. But if you follow the link in TFA to the company's site, they have a PDF which gives a bit more info on how their sensors work:
So whereas a phased array sensor works by comparing the arrival times of a wavefront at different locations to determine the direction the wavefront is traveling, it sounds like their gizmo is measuring in 3 dimensions the actual movement of air molecules caused by the sound wave, and deriving the wavefront travel direction from that.
What governments would those be which are restrained by the law, let alone common decency?
A representative government is a product of the law so of course it is restrained by the law. Just because individual actors within the government aren't 100% restrained by the law does not invalidate the principle that a representative government operates within the law.
The alternative to your nihilism is pure might-makes-right. Don't let the perfect be the enemy of the good.
When information is power, privacy is freedom.
One difference I can think of between electromagnetic radiation and sound waves is that the former are transverse waves and the latter are longitudinal waves. Does that make much of a difference for these purposes?
It's been explained already by Solandri but I'll give it a try. The sensor measures the displacement of the air, not the pressure. The GP post argues that it measures the vector sum of the displacement caused by all sounds, and this is correct. I imagine a small light ball that's magnetically suspended and being pushed around by the air, and the movement of the ball is recorded (this is probably not how it's done, I imagine it would have a highly non-linear frequency response). If there are two sounds from different directions with different frequencies, you could easily tell them apart -- e.g. the ball is moving up and down fast, and left and right slowly. If the sources have the same frequency, or it's just some broadband noise, you can't tell them apart. You could probably do it easily with two vector sensors and relative timing, but the whole point was that you can do it with one sensor in plausible conditions.
As for electromagnetism / sound, you are right that the transverse/longitudinal distinction makes a difference. The air displacement is analogous to the electric field. An RF antenna sort of measures the projection of the electric field onto some given axis, and an omnidirectional antenna measures approximately the absolute value of the electric field. (A mic may measure pressure, not displacement, but these are alternative variables for discribing the same wave). An analogous RF detector to the sound vector sensor would be three small linear antennae pointing in linearly independent directions, measuring the x,y and z components of the electric field as functions of time. The transverse / longitudinal distinction comes in here: the EM waves have an additional degree of freedom, namely polarisation. The E field can point in any direction perpendicular to the direction of propagation. Given the polarisation vector you can thus only constrain the vector to the source to a plane.
Oliver's law of assumed responsibility: If you're seen fixing it, you will be blamed for breaking it.
I just got back from a pleasure trip. I took my mother-in-law to the airport.
I think it would be New England Patriots coach who really really wanted this.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
"Acoustic zoom" beam-forming microphones have been available since 2010. Their main commercial product is an "acoustic camera" with 128 microphones on an 0.4 meter disk. They have other surveillance products, but they are "not approved for unlicensed users". This is already in use at FCI Otisville, a US prison. "This technology allows an operator to listen to various locations within the range of the system without any movement of the equipment. ... (T)his ability means the operator does not have to move about in order to "point" the equipment at his target and thereby draw attention to him potentially compromising the investigation."
With these systems, if you have enough recording bandwidth, you can record all the microphones and do the beam-forming later. So it's possible to pick the target at playback time. Squarehead is partnering with Galleon Embedded Computing, which makes 8 terabyte recorders full of flash devices capable of recording at gigabit Ethernet rates, so that's presumably what they're doing.
There are several other vendors now. This isn't really that hard to do.
So this technology is already out there, listening to crowds and pulling out single conversations.
Mod parent up. This is not a microphone, it's a differential hot wire anemometer.
I remember seeing a presentation by these guys when they were probably still a recent startup company at Twente University, must have been around 15 years ago. Their sensor is build with MEMS technology and consists of 2 or 3 tiny wires (maybe 1x200 micron) that are suspended over a valley etched out of a silicon wafer. When these wires are heated up, a sideways airflow will cause tiny difference in temperature between the wires that can be read out by measuring the resistance. At the time, their target application was low-cost microphones for use in mobile telephones. IIRC, the sensitivity of this sensor had a sensitivity that rolls off as 1/f inherent to the involved physics and they were struggling with the noise at high frequencies in the reconstructed sound. Looking at their website, the sensor still looks exactly the same. Assuming no major breakthrough (I could imagine they lowered the noise by a factor 10 meanwhile, but not that they solved the 1/f problem), I guess the major change now is that they can do more fancy signal conditioning with a DSP in real time. Too bad they went for the military market, but I guess that is a way to slap a few 10-Euro sensors together and sell them as a 10kEuro package. Does anyone know what could be done with these direction sensitive flow-sensors that cannot be done with a phased-array of conventional microphones?
karma police: arrest this man, he talks in maths; he buzzes like a fridge, he's like a detuned radio. [radiohead]