[HN Gopher] Optical microphone can separate multiple instruments...
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Optical microphone can separate multiple instruments from afar
Author : sohkamyung
Score : 72 points
Date : 2022-06-27 05:58 UTC (1 days ago)
(HTM) web link (newatlas.com)
(TXT) w3m dump (newatlas.com)
| orbital-decay wrote:
| Incredible separation, I don't think it's attainable by any other
| means. Should be super useful for speech in noisy environments.
|
| I have a question though, is capturing lateral movements of a
| single spot on the instrument enough to represent how it sounds
| for a human ear? I think it's equivalent to a polarizer filter as
| it doesn't seem to be capturing depth axis vibrations.
| jcims wrote:
| These example audio at the bottom. Seems the answer is no. But
| you could potentially use it as a means to isolate the sound
| from the recorded audio. You would have to synchronize the
| phases though because the optical speed of sound is c.
| infogulch wrote:
| > it doesn't seem to be capturing depth axis vibrations
|
| Good point, the paper mentions x-axis and y-axis, but doesn't
| mention z-axis. Maybe depth vibrations could be resolved as
| changes to the interference pattern?
| pbhjpbhj wrote:
| Do human ears resolve sound in more than one dimension? I've
| always considered that, per ear, we only get a sequence of
| compressions and rarefactions on the ear drum, that other
| aspects of hearing are through combination or 'cheating'
| (skin sensitivity and such). So, would it matter?
| macgyverismo wrote:
| I love the creative use of the rolling shutter, instead of seeing
| it as a downside, they turned the line-by-line nature of the
| sensor into sample rate multiplier.
| yodon wrote:
| Is technique this significantly different from the laser
| microphones[0] that intelligence services have been using for
| many decades?
|
| [0]https://en.m.wikipedia.org/wiki/Laser_microphone
| medler wrote:
| It builds on the technology behind laser microphones. According
| to the paper, visual vibrometry has historically required
| expensive cameras, and their method removes this need and
| appears to have other advantages over using a high-speed
| camera. They say they contribute "a novel method for sensing
| vibrations at high speeds (up to 63kHz), for multiple scene
| sources at once, using sensors rated for only 130Hz operation.
| Our method relies on simultaneously capturing the scene with
| two cameras equipped with rolling and global shutter sensors,
| respectively."
| klabb3 wrote:
| Combined with sophisticated noise cancelation and other
| relatively mature tech, this could make intentional focus
| listening possible, analogous to looking _at_ something, as well
| as closing your eyelids, but for hearing.
|
| Imagine being able to shut off specific ambient noises (and
| sometimes.. people) without losing spatial awareness. Or tune in
| a source you're paying attention to (the cocktail party problem).
|
| The issue with super-hearing would be to re-adjust expectations
| of who can reasonably hear us. Could be used for creepy things,
| obviously..
| iguana_lawyer wrote:
| Could an optical microphone be used to identify materials using
| resonance frequencies?
| wanderingstan wrote:
| This tech could be applicable to ticketing loud vehicles, as
| discussed here earlier this year:
| https://news.ycombinator.com/item?id=30364669
| anfractuosity wrote:
| Ooh that's really cool that they're using the laser speckle
| pattern. I like the fact they exploit the rolling shutter too.
| Something which https://people.csail.mit.edu/mrub/VisualMic/ also
| does.
|
| There are devices which are called laser doppler vibrometers,
| which might also be able to do this by pointing at the
| strings/base of the guitar?
|
| There do seem to be videos of laser doppler vibrometers being
| used with guitars on youtube, but I'm not sure if the soundtrack
| that goes along with them is just from a normal mic.
|
| I had a little play with laser speckle patterns to detect
| keypresses, as they can help find very subtle changes to a
| surface - https://www.anfractuosity.com/projects/fun-with-
| speckle-patt... (by 'diffing' the patterns)
| anigbrowl wrote:
| I've been doing pro audio stuff or 25 years and this is a
| landmark paper, biggest breakthrough I've seen in years. I'm
| _astonished_ at the quality of extracted signals. Biggest thing I
| 've seen since deconvolution became good enough for realtime or
| near-realtime adaptive noise reduction.
| de6u99er wrote:
| I hope this can be used to objectively distinguish between real
| audiophile equipment and audiophile snake oil.
| capableweb wrote:
| Then please read the submitted article, the press release
| (https://www.cs.cmu.edu/news/2022/optical-microphone) or the
| paper itself (https://www.marksheinin.com/_files/ugd/a41a28_7
| d370603fafd41...) again, as it has nothing to do with audio
| quality.
| TheHideout wrote:
| This seems like an interesting optical solution to the "cocktail
| party problem", which can be solved using Independent Component
| Analysis [0]
|
| [0] https://en.wikipedia.org/wiki/Independent_component_analysis
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