This is a fascinating article. I'm not sure I dig the hypersonic technology, but I can see that it would certainly have it's uses. Imagine throwing a huge party and not having to worry about the neighbors calling the cops because your music is too loud. Rich could play his guitar without having to worry about the asshole upstairs. And you wouldn't need headphones to listen to your iPod anymore.
I can totally see it backfiring, too. For instance, imagine the technology being advanced enough that kids record the answers for an upcoming exam at school that only they could hear. The teacher would never know!!
Another neat article from National Geographic, this one take place in Colombia.