Virtual Airwaves is working in this space.

https://virtualairwaves.com/

and see their iOS app: https://appsto.re/us/jrj3hb.i and the web app: https://cb.virtualairwaves.com/channel/1

They have several patents on "3D Audio" style techniques to give distance cues via the signal:

See:

https://patents.google.com/patent/US9730023