Guest question by GQHero Logik.

In the audio clip you can listen to some routine activity. The sound has been post processed to bring it down to the human audible frequency range.

[audio:03apr10qsound.mp3]
Id this activity.
To help matters, this sound can be detected/recorded using instruments of the kind shown in the image. This instrument has seen military applications as well, mostly for detecting sounds in its niche domain. Id the instrument.

Super-toughie, seemingly cracked only by Rogi! Great job, sir!

Check out logik’s comment for the answer!.

Rogi and Logik