I've often wondered what the woo woo sound is, I think it might be street cleaners, apart from the inconvenient fact it happens late at night. However it may explain the phenomenon of the beer can being blown along by the wind which you can never see the next morning. My weirdest noise was about 3 am, a low growl accompanied by a high pitched squeal, so far, so fox, but then I heard a womans voice singing! This seemed to be right outside my window, fortunately I'm a total coward so didn't investigate further. I went to bed pronto.