Tech TV did a story on him.
You should have seen it, utterly amazing. Unless the "speaker" was pointed directly at you, you can't hear it. The sound travels in a very contained and precise "beam". Contrary to want is being advertised, ultra sonic frequencies can be used as a deadly weapon.
Another good link.
http://www.businessweek.com/magazine/content/03_07/b3820075_mz018.htm
