i know that there is a topic about vintage images, so what about recordings?
B&N Mobil Directo Demonstration (1950): https://m.youtube.com/watch?v=r5KmS2Gufic
New York City Civil Defense Drill (1951): https://m.youtube.com/watch?v=zF5R_ypxWic
North Vancouver Siren test (1976): https://m.youtube.com/watch?v=1j_PhNKbJaE