Blind Boy Masters Echolocation

This is an amazing video about a blind boy who has mastered echolocation so well that he can walk down the street, rollerskate, and play video games -- all unassisted.

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But seriously, cool story. Also, what a fantastic mother that kid has! The video was well-done.

Have any serious scientific studies been done with him, looking at the frequency range of those clicks, or his ability to distinguish between materials objects are composed of?