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.'"

Yawn

[ArchieBunker]

Gene Hackman was doing this in the 1970's http://www.imdb.com/title/tt0071360/?ref_=sr_1 [imdb.com]

Not the future I want to live in

[Coditor]

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.

Re:a few laws of physics problems here

[SuricouRaven]

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.

Re:a few laws of physics problems here

[ebno-10db]

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?

Re:a few laws of physics problems here

[Jah-Wren Ryel]

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.

This is pretty old technology

[photonic]

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?