Commenting on your response:
http://www.straightdope.com/classics/a2_114.html
just an update from the above link…
If I’m not mistaken some attempts to directing a sound to a certain point is now can be achieved, just like laser. An inventor demonstrates a device that can directly points where the sound can be heard only at that certain point.
Maybe not as destructive as lasers but potentials are well thought I presummed.
Sorry that I forgot the link, but I’m sure I got it over the net.