The specific spoken words are

"This is an emergency broadcast. Nuclear missile inbound detected. Seek shelter, duck and cover, and brace for impact".

I heard this on a recent tech presentation, and I'm pretty sure its recorded from a movie or TV show somewhere, likely something from Monty Python or Douglas Adams or Doctor Who... (British Scifi Comedy). It's amusing because of the delivery speed, and the tone of the woman speaker.

Here is the link to the actual recording. The link will start you about five seconds before the quote begins...

Any idea as to the origin of that recording?