N.Y.P.D. to Limit Use of âSound Cannonâ on Crowds The Police Department has agreed to stop using an âalertâ noise on the devices after demonstrators and photographers sued, saying it caused migraines and dizziness. A police officer held a Long Range Acoustic Device, or âsound cannon,â as protesters marched through Times Square in 2014.Credit...John Minchillo/Associated Press April 19, 2021Updated 4:30 p.m. ET Police officers first deployed the earsplitting beeps against protesters more than a decade ago in Pittsburgh: Painfully loud noises emitted from a powerful speaker atop a police vehicle, a crowd-control device known informally as a âsound cannon.â