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Well as it happens there are special sonar cameras out there capable of providing real-time video images[0][1].

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....

Not quite the same thing though. These systems are active. They have sound being produces most likely at a very specific frequency and then listened for so that depth information can be gathered. This instead images the sound that's already out there in the light. It's the difference between lidar and a camera

Nope, theirs is the sound-camera, detector array and sound-lens, but with an acoustic floodlight. I think they do use ranging though, so the 2D image is "sound camera" in one raster dimension, and "sonar range" in the other.

Sounds to me more like the difference between using the flash or not.

Sort of, except the "camera" can't make any use of "light" generated by anything other than the flash.

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