Possibly the most fear-inducing man-made sound ever created.
Another amazing Reddit thread on what it was like in the 1980s living under the imminent threat of nuclear annihilation: here.
An eye opening quote from the thread:
"I remember in elementary school gym class (pre-Colombine obviously), we had a game called "Run Home" - we would meet in the soccer field and the teacher would blow the whistle. We would all run home, touch our front door and run back.
I found out later that if you could do it in under 20 minutes, the school would let you go home if the nukes were coming so you could die at home with your family (if they were home or could make it home) rather than at the school. Fucking terrifying to think about that as an adult."