Imagine a wall of microphones next to a truck - you can tell which part of the wheel makes the sound. That sort of stuff.
As for an actual "camera" that turns sound into an image - i've never heard of one.
I have. His name is Daniel Kish [1, 2].
Apparently his visual cortex has learned to process sound rather then light, so he literally sees, based on the sounds he is hearing.
Your point about only him appreciating his own experience is interesting, as the same question can be asked of all of us [1]. In audio, maybe apples and oranges are the same colour and strawberries are different? It would be an interesting application of a sonic camera, to render the image so that equivalent audio colours are consistently mapped to the same light colours.
[1] https://www.quora.com/Visual-Perception-Is-everyones-experie...
SOund Navigation And Ranging: https://en.m.wikipedia.org/wiki/Sonar
Think laser rangefinder on a scanner platform vs a camera.
I'd challenge the notion however that this isn't 'just' a passive SONAR device. Keeping the camera analogy, active SONAR use spread spectrum pings, much like the white light of a camera's flash. Your camera lacks a flash function, and its lens is maybe not yet as in focus as it could be.
If you did want to add a flash, you're likely a $0.02 piezo device and maybe $20 in other various parts (and heaps of numerical processing on a PC) away from having the ability to produce a nice 3D reconstruction of the physical scene.
If you get direct data capture going, please do post some raw data online. I'm sure others would have heaps of fun playing around with it.
One file per cell, 16bit integer samples. Stored row by row, 128 slices per frame.
Not sure where to post it, however - here it would be buried.
http://blueprintsubsea.com/starfish/images/sonar/452/sf452_s...
That's just one example - look for side scan sonars for the earliest stuff (https://en.wikipedia.org/wiki/Side-scan_sonar) or sonar imaging for the latest stuff (http://www.tritech.co.uk/product/gemini-720i-300m-multibeam-...)
This project is similar in that it involves visualization from audio, but apart from that, it's quite difference. This is the ability to see a sound. To derive the positions of arbitrary sounds in a viewing plane, and render it like you would a picture or video.
Most sonar is active (sends out pings) and has only one input (one microphone)
It builds pictures by directing the ping and measuring time until the response.
This is fundamentally different than an array of microphones passively listening to, and creating a fine grained picture of some sound source.
While I believe the US Navy doesn't prefer the term "Passive Sonar", submarines and some surface ships are equipped with hydrophone arrays (either on the hull, or towed arrays, or both) as well as active sonar; this isn't an uncommon thing. (I was under the impression that the active sonar didn't use a single hydrophone, but instead used the same hydrophone array used for passive detection.)
For my undergraduate project years ago I built a microphone array that could be used to locate noisy objects. I demonstrated it by tracking aircraft taking off at a local airport.
Whilst I didn't make 'acoustic photos' with it, I did plot the flight track of the aircraft in real time, and could have a decent crack at identifying it based on frequency content.
Cool stuff!
- Kai @ nlacoustics.com
It's used my military & events for drone tracking by sound, and concert venues for seeing where sound leaks out to the surrounding neighborhood. (Among other uses)
Edit: Their example screenshot is even showing an engine block overlaid with acoustic output of the components: http://static1.1.sqspcdn.com/static/f/1431009/18268254/13373...
The use case here is being able for a diver or ROV to see in murky water
[0]http://www.soundmetrics.com/image-gallery [1]http://www.apl.washington.edu/programs/z_DIDSON/Pages/LIMIS....
I'm unaffiliated, but saw one of their demos.
The use case I imagine is finding what part of a machine is emitting a noise, much like how you would use a thermal camera for finding what part of it is running hot.