Focused sound

From: Mok-Kong Shen (mok-kong.shen_at_t-online.de)
Date: 08/27/04 

Date: Fri, 27 Aug 2004 19:31:57 +0200

I learned that there is a new invention of directing sound
as a focused beam to a target:

   http://www.popsci.com/popsci/science/article/0,12543,351353,00.html

It seems that it could have some quite real, though apparently
limited, usages for secure communication via voice.

According to the article: 'Step into the beam and you hear the
sound as if it were being generated inside your head'. So it's
sort of compromising one's consciousness.

M. K. Shen