Actually a form of targeted hypersonic sound waves does exist, kind of makes me wonder if you could in fact make somebody "Hear voices in their head"(in the crazy kind of way) with it, though you have to be rather close. Think what you want, I'm just tossing some relevant information out.
Here is and article from a well known science magazine about these sound waves:
http://www.popsci.com/popsci/science...351353,00.html

Just My Random 2 pesos
-AzE-

[EDIT] I was missing a word, sorry