LX March 31, 2020 1:42 pm The Emergency Alert System: Everything You Need to Know We’ve all heard it: the Emergency Alert System. That loud sound signifying a national emergency. But who decided to use that sound? And is it designed to be that annoying? US & World Videos 0:45 Car crashes forces vehicle to slam into Leimert Park home 3:14 LAPD officers return to USC amid pro-Palestinian protest 1:37 Pro-Palestinian protesters gather outside White House correspondents' dinner 2:42 USC students share thoughts on cancelation of main commencement 0:45 Where will the 2025 NFL draft take place?