The signal you will be hearing during this siren test is the one used to alert the general public to a public announcement. It consists of a siren wail that rises and falls over a sixty-second period. Its purpose is to warn of a serious threat to public safety and prompt people to switch on their radio sets to listen for announcements. There is no need for you to take any action when you hear the alert on 13 March as it will really only be a rehearsal.