There's not much to say except take a look at the NEWS article I just posted that announces a hand-portable sensor that can enable the user to hear breathing from 50 feet away through a 12 inch concrete wall.
Technology usually takes years to go from concept to product. The RadarScope is a vindiction of the DARPA fast track programs.
I'd like to hear from you, but especially from those who wrote me saying the technology just wouldn't work.
Finding out the perceived frequency response of your combined headphone/ear 'system' and compensating for it using parametric equalization can offer some eye-opening benefits. But finding an EQ solution isn't always easy.