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I've actually done this in a lab with a laser - it's a fun trick. What the original article talks about though is passively measuring sound from objects using

I've actually done this in a lab with a laser - it's a fun trick. What the original article talks about though is passively measuring sound from objects using a camera - no laser. Although they're measuring the same thing (physical vibrations of objects) the way they're doing it is actually quite different.

petertodd 9y ago
A friend of mine used that technique while working in an entomology lab studying the mating habits of cockroaches. They were trying to figure out what kinds of vocalizations the cockroaches were making while mating, and bouncing a laser off their shell was by far the easiest way to record those very quiet sounds. It's been a few years, but I think this was the manufacturer: https://www.polytec.com/us/vibrometry/products/ https://www.polytec.com/us/vibrometry/products/ I wouldn't be surprised if the non-laser techniques eventually also show up as off-the-shelf products too, simply to reduce costs - a simple camera could be cheaper than a laser, and might have advantages in being able to record sounds off multiple points at once.
- slazaro 9y ago
  Also, I think a big advantage for the camera-based solutions is that they're totally passive, while laser-based need to interact with the object.
  - Zigurd 9y ago
    To make a camera-based solution practical, it seems like one would neeed a specialized camera, for modest resolution, but very high frame rate. Without enough frame-rate, you can't capture high frequencies. Even if speech could be discerned from a spectrum that rolls off at 300hz, well under the peak energy of a typical human's speech, you would still need many hundreds of frames per second.
    - fisherjeff 9y ago
      If you watch the video at the end, you'll see that they actually exploit the fact that CMOS pixels are read out sequentially and use the data from each row to extract surprisingly decent high frequency data from even 60 Hz video!
    - mikeash 9y ago
      They article says they were able to use the rolling shutter on standard cameras to extract data at a much higher frequency than the nominal framerate would allow.
    - regularfry 9y ago
      The article talks about this. The rolling-shutter effect means that you can get information out at higher than frame rate.
- kriro 9y ago
  Pretty cool idea but I would be a little worried that the laser itself could influence the mating habits due to heat/distraction etc.

petertodd 9y ago

A friend of mine used that technique while working in an entomology lab studying the mating habits of cockroaches. They were trying to figure out what kinds of vocalizations the cockroaches were making while mating, and bouncing a laser off their shell was by far the easiest way to record those very quiet sounds. It's been a few years, but I think this was the manufacturer: https://www.polytec.com/us/vibrometry/products/ https://www.polytec.com/us/vibrometry/products/ I wouldn't be surprised if the non-laser techniques eventually also show up as off-the-shelf products too, simply to reduce costs - a simple camera could be cheaper than a laser, and might have advantages in being able to record sounds off multiple points at once.

slazaro 9y ago
Also, I think a big advantage for the camera-based solutions is that they're totally passive, while laser-based need to interact with the object.
- Zigurd 9y ago
  To make a camera-based solution practical, it seems like one would neeed a specialized camera, for modest resolution, but very high frame rate. Without enough frame-rate, you can't capture high frequencies. Even if speech could be discerned from a spectrum that rolls off at 300hz, well under the peak energy of a typical human's speech, you would still need many hundreds of frames per second.
  - fisherjeff 9y ago
    If you watch the video at the end, you'll see that they actually exploit the fact that CMOS pixels are read out sequentially and use the data from each row to extract surprisingly decent high frequency data from even 60 Hz video!
  - mikeash 9y ago
    They article says they were able to use the rolling shutter on standard cameras to extract data at a much higher frequency than the nominal framerate would allow.
  - regularfry 9y ago
    The article talks about this. The rolling-shutter effect means that you can get information out at higher than frame rate.
kriro 9y ago
Pretty cool idea but I would be a little worried that the laser itself could influence the mating habits due to heat/distraction etc.