Yup, I understand, it's a passive detection process simply measuring relative energy impacts on the plates, then determining location by measuring differential positioning of the same resistance patterns from each independent sensor.

Like an umbrella with a hole in it over a driveway in the rain. The area with the hole is going to be further penetrated by the water and leave the impact result on the driveway. The driveway is the sensor, the hole is the void, and the umbrella is the stone.