The LRAD was used against peaceful anti-globalization protesters in Pittsburgh in 2009.
One can only hope that we will not see a rise in sound cannon police brutality as we've seen with pepper spray police brutality in California and elsewhere. But unfortunately it appears that law enforcement is expanding its arsenal of weapons -- and even looking to the military for ideas -- for use against people exercising their First Amendment right to protest against repression and government abuse and speak truth to power.
The ACLU filed a federal civil rights lawsuit against the police in the aftermath of the Pittsburgh incident on behalf of a professor who was assaulted by the LRAD device as she was observing the protest. She alleges that she suffered permanent hearing loss among other injuries.