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from the Lindsay-Wagner-says-she-has-first-dibs dept.
In case you can't get enough news about graphene:
As a species, humans have evolved to have certain strengths and weaknesses. While we don't have the sonar-like range finding capabilities of bats or dolphins, we do have the brains to engineer a device that can give that capability to us.
Researchers at the University of California, Berkeley have done exactly that in their development of tiny ultrasonic microphones made from graphene.
[...] At only one atom in thickness, graphene possesses the key properties of strength, stiffness, and light weight; so it is extremely sensitive to a wide-range of frequencies. In this case, the microphone can pick up frequencies from across the human hearing range—from subsonic (below 20 hertz) to ultrasonic (above 20 kilohertz)—and as high as 500 kHz. (A bat hears in the 9 kHz to 200 kHz range.)
Daredevil, here we come!
(Score: 2) by TheLink on Thursday July 09 2015, @03:16AM
While we don't have the sonar-like range finding capabilities of bats or dolphins, we do have the brains to engineer a device that can give that capability to us.
We're not as good as bats or dolphins at such stuff but as far as I know, very many of us can tell where objects are from the sounds they make or from the echoes off them. If someone makes a noise at a particular spot we know roughly where they are.
I suspect bats and dolphins sonar works in a similar way too and developed from the ability to hear where stuff is and not so much in the old style[1] submarine "send ping out time how long it takes to come back" range finding. Because ee don't have to be the ones sending the "pings". If someone _else_ claps their hands we can still tell how far and where a brick wall is based on the echoes of the claps coming off it.
So if you have good enough hearing and you have enough practice, you can make clicks or other noises and get an idea of where stuff is by hearing where the objects are from the echoes bouncing off them.
You might not get as good as those in this video but might still be useful: https://www.youtube.com/watch?v=AiBeLoB6CKE [youtube.com]
[1] I suspect modern submarine sonar has advanced leaps and bounds over that, otherwise it's kind of pathetic.
(Score: 0) by Anonymous Coward on Thursday July 09 2015, @03:28AM
(Score: 2, Informative) by anubi on Thursday July 09 2015, @07:58AM
Beamformers.
One captures the acoustical signal from several transducers at known locations.
The acquired waveforms are each broken down by Fast Fourier Transform into frequency and phase and are correlated to each other.
( It is important that the actual digitization from all acoustical receivers is synchronous. Differences in arrival time is how the vectors are calculated. )
This makes doppler shifts stand out like a sore thumb.
What you will get is a very detailed vector to whatever is making the noise as well as how fast and in which direction.
Funny thing... you know how you can recognize a person by their voice? Every submarine in the world sounds different too! There are so many things that "flavor" the tone of a submarine's drive train acoustics that no two sound alike.
Interested? Google "sonobuoy". [google.com]
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]