Tacit Project. Haptic Sonar For The Blind.
grathio.com
grathio.com
As a sighted person, I don't have much use for it, but I think it would be interesting to see it in action.
The fact that it's built on an Arduino also means that anyone with an idea can hack up a new version of it and try their idea. Amazing.
There have been multiple efforts over many years in this direction but none have been as configurable (I have worked on a auditory-headband based on similar hardware).
Wondering how easy it would be to interface with a phone using the Android Accessory kit.