As technology advances and our society evolves, so does everything that comes with: social protest, human rights, privacy, justice, law enforcement, education, etc.
The Police Department of New York recently used an LRAD (Long Range Acoustic Device). It is a portable sound speaker designed to scare people away with sound. But there is more to it than scaring people away and dispersing a crowd. Even if you would be able to withstand the ‘fear’ that would overcome, and decide to remain in place, you would be overwhelmed by agony, confusion and pain. It was deployed for the first time during the Ferguson riots, and it seems to become a wanted item for Police departments.
The LRAD device is developed by LRAD Corporation, formerly known as the American Technology Corporation.
Source: The New Sound of Crowd Control