Echolocation works well for a lot of people who cannot see, just as long as there is not a lot of background noise. I have an idea that could enhance the concept of echolocation and make it usable in places with a lot of background noise and possibly enhance the accuracy even in quiet settings: A small electronic radar device that clips on to the belt. The device sends out a pulse of radar when the user presses a button; and when the pulse returns, it is instantly converted digitally into an audible sound that the user hears through an I-pod style ear-piece speaker... a fairly simple and inexpensive device. I hope to see some research done on something like this. I have a feeling it might work really well. This might also work using something similar to the laser measuring devices that carpenters use, but the return results come back as processed audio data.