The story of natural gas in PA is so prevalent, it's now even in This American Life. The piece starts out with a fun story of discovery but devolves into a story of giant corporation trampling on the little guys.
One of the things you could do would be to spread out the return sound over a loger period of time so the ears can "resolve" things more precisely but with a shorter update rate. You might also use consecutive signals from 2 different spacial locations, say on the left and right side of your body to give another variable for your brain to interpret the 3D nature of the space (though I'm not sure if you get a lot more signal for this, since you already have 2 receivers). The last thing you can do is send multiple frequencies out one after another so you can have yet another variable to interpret. How your brain puts this all together will be non-trivial, but each controlled variable introduces more opportunities to dis-ambiguate the world. As for another medium bandwidth input, there is the tongue Blind Learn To See With Tongue