Someone suggested this very irritating noise, which seems to be used universally by Zoo visitors everywhere, stems from a modern film like the Lion King, but not having seen it I do not know about that.
It is probably based on a chimpanzee food hoot, which TV films use out of context, because it is a distinctive sound:
I saw zoo visitors doing it in front of gorillas, among others. I guess one can even trace down a particular canned recording in a TV show.
https://www.quora.com/Do-monkeys-really-say-ooh-ooh-ah-ah