I found this
http://adage.com/article?article_id=122491
Aside being the most obnoxiously evil thing to have fallen into the hands of adfucks since the radio, it may have uses included in an instillation piece. I would need to tinker with a couple of the Audio Spotlight systems myself, but imagine if you could rig a series of them in a room, using binaural tones
http://en.wikipedia.org/wiki/Binaural_tones
so that as someone moved within the room different frequencies would interact with the persons brain and create a number of different effects relative to their placement.
What do you think?
http://www.holosonics.com/technology.html