This technology scares the heck out of me.
I am sure you can also imagine when and where they would you such technology.
May be better than rubber bullets, gas, etc...
The fact that it can target a particular group of people is of concern.

This would put an end to gatherings that weren't on the correct agenda.  (Curious if it is not already being used.)

http://minnesota.cbslocal.com/2011/06/06/screech-machine-could-drive-teens-away-from-park/