
If you watch closely enough, everything is a speaker - jXCw1N0jtH3
https://kottke.org/18/01/if-you-watch-closely-enough-everything-is-a-speaker
======
nwatson
Impeached Arizona governor Evan Mecham (shortened term 1987-1988) was probably
very paranoid during his time in office, but nobody gave credence to his
concern over the possibility of "reflected laser use" to surveil him. From
Wikipedia
([https://en.wikipedia.org/wiki/Evan_Mecham](https://en.wikipedia.org/wiki/Evan_Mecham))
...

    
    
        Throughout his administration, Mecham expressed concern about
        possible eavesdropping on his private communications. A senior
        member of Mecham's staff broke his leg after falling through a
        false ceiling he had been crawling over, looking for covert
        listening devices. A private investigator was hired to sweep
        the governor's offices looking for bugs. The Governor was quoted
        as saying, "Whenever I'm in my house or my office, I always have
        a radio on. It keeps the lasers out." After this was reported,
        a political cartoon by Pulitzer Prize winning cartoonist
        Steve Benson appeared in the Arizona Republic depicting the
        governor leaving his house outfitted for laser tag. When asked
        about this by reporters, Attorney General Bob Corbin replied in
        amusement, "We don't have any ray gun pointed at him."
    

The guy was a tool but the guy had a point about surveillance technology, and
nobody took him seriously.

~~~
blincoln
No one took him seriously because "I always have a radio on. It keeps the
lasers out." is a textbook example of the kind of thing someone experiencing
paranoid psychosis will say.

i.e. there are certainly listening devices that operate based on bouncing a
laser off of a window[1] (or some other object), but his use of a quasi-
magical protective measure (radios allegedly protecting against lasers) - in
addition to the other behaviour mentioned - strongly implies that he was in
need of psychiatric care, as opposed to being under surveillance.

FWIW, I've met multiple people with paranoid psychoses of one sort or another,
and _all_ of them have incorporated elements of real-world technology into
their delusions.

[1] e.g. [http://www.lucidscience.com/pro-
laser%20spy%20device-1.aspx](http://www.lucidscience.com/pro-
laser%20spy%20device-1.aspx)

~~~
totalZero
Is he wrong? Adding noise from a radio or TV in the room may be an effective
way to obfuscate attempts to use laser reflection surveillance on a window or
other diaphragm. Both the device and the person speaking will cause the laser
to jitter as the window vibrates.

------
knolan
Here is the project page from 2014:

[http://people.csail.mit.edu/mrub/VisualMic/](http://people.csail.mit.edu/mrub/VisualMic/)

And previous discussion:

[https://news.ycombinator.com/item?id=8131785](https://news.ycombinator.com/item?id=8131785)

[https://news.ycombinator.com/item?id=9254654](https://news.ycombinator.com/item?id=9254654)

~~~
jwilk
Also:
[https://news.ycombinator.com/item?id=16201745](https://news.ycombinator.com/item?id=16201745)

------
kwhitefoot
> The group tested an eclectic selection of materials, including a bag of
> chips (excellent), a soda can (surprisingly mediocre), and a potted plant
> (average). They were even able to recreate music playing using footage of
> the vibrating ear buds. The best material of all was the thin foil wrapper
> on a Lindt chocolate bar Davis had been snacking on.

I hope it was the journalist who thought the soda can was surprisingly
mediocre and not the researchers. The soda can is immensely stiff compared to
the foil and much heavier so it will not move so much, meaning that there is
simply less for the camera to see.

~~~
batbomb
A thin foil wrapper is exactly a ribbon mic.

------
Robin_Message
Another cool thing is recovery of picture from ambient reflected light. Sadly
it only works on CRTs.

[https://www.cl.cam.ac.uk/~mgk25/emsec/optical-
faq.html](https://www.cl.cam.ac.uk/~mgk25/emsec/optical-faq.html)

~~~
fjsolwmv
You can indirectly photograph any object via its reflectivenes if you have a
movable trackable light source and a camera pointed at a wall the object is
facing.

------
sytse
Everything is a microphone?

~~~
nayuki
The original research in 2014 is presented well. This article in 2018 butchers
the terminology, using "speaker" instead of "microphone".

~~~
GuiA
Speakers and microphones are both transducers, which is what the author seems
to be getting at.

~~~
lostmsu
But leafs shake because they receive waves. Not the other way around.

~~~
CPLX
Another valid metaphor though is that video of the leaves can be decoded the
same way video of a speaker would. The analogy works either way.

~~~
nkoren
Yup. Interestingly, actual speakers work either way too. Reverse the polarity
on them and you can use them as a crappy microphone.

------
ttflee
TL;DR Laser window bug upgraded to high speed camera/DSLR using scanning delay
between rows of pixels.

------
CapacitorSet
Silly question: isn't this phenomenon bound by the Nyquist limit, which means
it would take at the very least 4k fps to reconstruct music (considering that
a soprano can get no higher than 2 kHz)? That sounds like an impossibly high
framerate.

~~~
coldtea
4K fps? Impossibly high? Not at all. There are consumer compact cameras and
even smartphone sensors that can hit 1K fps [1] -- and those are not even
specialist high speed cameras.

Specialist cameras hit 4k fps at second gear, and can go as high as million
fps (and even trillion fps [2])!

Besides, this is about reproducing music frequencies, whereas the most
probable target for this technology is eavesdropping, not as a replacement for
Neumann U87 -- and for that you need way less range.

[1]
[https://www.theverge.com/circuitbreaker/2017/2/7/14532610/so...](https://www.theverge.com/circuitbreaker/2017/2/7/14532610/sony-
smartphone-camera-sensor-1000-fps)

[2] [https://newatlas.com/fastest-camera-44-trillion-frames-
per-s...](https://newatlas.com/fastest-camera-44-trillion-frames-per-
second/33330/)

~~~
dorgo
wait, 4.4 trillion fps with a resolution of 450 x 450 ? Isn't it petabytes of
data per second?

------
k__
I once heared radio news coming out of my electric guitar, pretty scary.

~~~
err4nt
When I was growing up, we would often hear radio stations faintly in our
vehicle after we had parked it and shut it off on our driveway - that's how I
learned that radio waves go through everything all the time. It wasn't just
one time or one vehicle, it happened in quite a few spots on our driveway.

------
fit2rule
Disclaimer: I work for a professional microphone manufacturer.

I wonder how long it'll be until this technique becomes feasible for recording
professionally? Like, instead of capsules and diaphragms, we just have a laser
that gets the cleanest, clearest possible signal it can, from the room around
you ..

~~~
mannykannot
Isn't one of the benefits of high-quality microphones that they can reject or
attenuate the ambient sounds and reverberations that you do not want?

~~~
CharlesW
Higher-quality microphones tend to pick up _more_ ambient sound because
they're more sensitive and/or have a larger frequency response.

"Worse is better" sometimes applies to mics as well. For example, new
podcasters are often advised to use cheap dynamic mics since it forces them to
get close to the mic (improving their signal-to-noise ratio) and doesn't pick
up audio over 15 kHz (which is not meaningful for voice recording).

~~~
mannykannot
more sensitive and with a wider frequency response but also directional and
with fewer resonances than what OP was suggesting.

------
userbinator
Somewhat reminds me of this hoax from over a decade ago:
[http://itre.cis.upenn.edu/~myl/languagelog/archives/002875.h...](http://itre.cis.upenn.edu/~myl/languagelog/archives/002875.html)

------
juskrey
What about to process some movies with this method, anyone?

------
misterandosan
Wow, "everything is a speaker" really fails to convey how crazy this is. The
implications for this in terms of surveillance seem to be massive!

~~~
mirimir
This is rather old news re surveillance.

~~~
_jal
I wonder about reconstructing "off-screen" or muted conversation/noise in
Youtube videos. Or CSPAN video.

------
TipVFL
I wonder if this could be applied to normal video and get results useful for
any purposes. I realize it would be lower quality, but I feel like it might be
possible to detect nearby gunshots on security camera footage that doesn't
have audio. How cool would it be to see a murder trial enter audio recovered
from footage of a house plant as evidence?

~~~
anfractuosity
See this -
[https://youtu.be/FKXOucXB4a8?t=187](https://youtu.be/FKXOucXB4a8?t=187)

They show audio captured from a 60fps video from a DSLR exploiting the rolling
shutter. I'm not sure if you can use less than 60fps though?

------
mozumder
Isn't this how those laser microphones work?

~~~
chatmasta
It's the same concept of detecting vibrations, but obviously this method is
using a camera and processing a video, while the "laser microphone" [0]
measures the difference in distance traveled by the laser beam.

It would be interesting to compare the two methods in various scenarios, i.e.
through glass.

Obviously the laser method will work at night while the video method will not
(probably depends how "dark" it is).

[0]
[https://en.wikipedia.org/wiki/Laser_microphone](https://en.wikipedia.org/wiki/Laser_microphone)

------
leoc
I was wondering about using smartphone cameras as drum-head pickups, but the
frame-rate problem put me off the idea. With the rolling-shutter trick it
seems that it might be almost useful on bass drums, at least as a trigger
rather than an audio source.

~~~
tmandry
I used to be a sound engineer for live shows. I could imagine high speed
cameras being used to replace instrument microphones in live performances one
day, much like optical mice replaced the roller ball style.

By keeping a fixed object in view of the camera (e.g. a reflector on the
stage), a camera could correct for its own vibrations and achieve perfect
rejection of outside noise, unlike most microphones which have a cardioid
pattern.

Probably a pipe dream, but cool idea.

------
bagacrap
"everything is a speaker, especially earbuds!" That example doesn't seem
particularly noteworthy.

------
madengr
I see everything as an antenna.

