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Walking around on your own and trying to echolocate is much different than driving in a car. The engine noise of a car offers a very good tone for listening to as it reflects off passing objects. I've tried a couple different methods so far for creating a noise that I can interpret. I've tried clicking, and I've tried just listening to my footsteps, and I've tried listening to my pants swish against themselves. Really, we're looking to interpret the reverb characteristics of the room or hallway.
I've got long straight hallways in my office building that have flat walls. Quite distinct as far as reverb goes. I've managed to walk down the hallway and notice when I'm approaching one of the sidewalls. But it doesn't become overly present until I'm less than a foot and a half away, at which point I can put out my hand to my side and touch the wall with decent accuracy. Obviously it's best to practice this when there aren't too many other noises around you like people talking, wind or machinery.
I think one of the things that helps with this is that the walls are directly to the side, making them a direct shot to the ear. Objects and walls directly ahead seem like they're a bit more difficult to detect. I'll have to work on that, it seems like it might be an important part...
Objects seem to be further than they sound
I find that other noises, like people walking or talking seem much closer than they actually are. This is probably because I am focusing on hearing everything and therefore everything is a bit amplified.
There are certainly objects which do make noise. Printers, machinery, water bubblers etc. which can not be ignored. I think these objects will play a critical role in navigation. Of course, this will probably only work if you are in an environment that you are already familiar with. IE, if you know where the printer is, you probably know on which side of it you should be walking, and approximately how far from it you should be. But I think these things are certainly useful and we should be using ALL of the sounds available to us to help locate.