Why wouldn’t one create a series of passive listening posts outside your perimeter composed of commercially available security system cams with good microphones?
You could run the whole thing wirelessly, silently, with few humans, etc.
Then, all you need to do is hook each up to a claymore, and ....
Batteries (electric, not the artillery kind), especially functional ones, are rather difficult to come by in your typical battlefield environment.
I like the way you think, however, can it be hacked?