That's the wind.
3 seconds sound clip from the Abbott & Costello Meet Frankenstein movie soundboard.
You can hear this line at 00:13:25 in the Blu-ray version of the movie.
Quote context
[...]
- Chick is right. This is awful silly stuff.
- You know that person you said that there's no such person? I think he's in there, in person.
- Listen, stop reading this thing. That's a lot of phony baloney to fool McDougal's customers.
- Now, fold up that canvas. Get busy. Come on.
- Dracula can change himself at will into a vampire bat, flying about the countryside. Flying. Wooo...
[...]