[Steve_Seattle]

"Sounded female, middle aged, white, and a touch of the local accent. But none of that means anything, because, as you say, It was probably synthesized."

I agree that it sounded like a white female, and I also wondered if it was actually the voice of someone associated with the RV, was synthesized, or was taken from some old audio footage in the public domain.

[livius]

“ or was taken from some old audio footage in the public domain.”

Interesting idea. It does sound like something from a grade-B disaster movie.