Civil defense sirens are mounted in fixed locations and used to warn of natural disasters or attacks. What is a siren noise?Ī siren is a loud noise-making device. It explains that a purge like this is routine and a part of YouTube’s ongoing efforts to ensure the site stays free from spam and abuse. YouTube is warning creators they may see their subscriber numbers decline this week as the result of a purge that will remove closed accounts from YouTube metrics. used for terrorist attack or immi- What is a YouTube purge? It can be heard in most of the franchise’s trailers, including the most recent movie, “The First Purge.” What does a constant siren mean?Ī “steady” blaring sound, the ‘Alert’ siren will be used as a severe weather warning. The siren is used to signal the beginning of the Purge. All “The Purge” horror movies feature a 12-hour window of time where all crime, no matter how violent, is made legal in the U.S.