It may be possible, but it's more complicated that you might think. It seems the original source is gone, but when some MIT students actually measured the effectiveness of tin foil hats, they could end up amplifying some frequencies: http://boingboing.net/2012/10/01/tinfoil-hats-actually-ampli...

It's hard to know without testing, but blocking this could require quite a lot of headgear. Way easier to build something that can take it better.