====Military Uses==== 

 I seem to recall an article a few years back mentioning the use of "directable audio" in psychological warfare (for instance, making an enemy believe his peers to be plotting his death, or that they are surrounded by a mass armed force, or as a useful interrogation technique - "I'm going crazy"). I can't cite the specific article, but there is definitely a Military use for this technology, especially nowadays. Ugly article though. =)