htt p://people.csail.mit.edu/rahimi/helmet/ (Remove the space after htt.. I can't post livelinks due to my low rep)
So why do you add the space? And the rules tell you not to post links only, give us a summary at least. For all we know it could be kiddie porn or drive by installations.
It's a serious experiment by some london students. They try some hats and and give them some freequensies, then meet the numbers of decibel. Because I can't post either. My rep wont allow it.
Right, I thought the link would be just plain text... Didn't know you can't post links at all. Maybe with the [code]Code Tags[/code] around it. Anyway, on to the tin foil hat research.