There's a nice rainstorm in Pat Metheny's album entitled "We Live There", it's one of those steering wheel bopping jazz tunes and then in the end, you hear a storm breaking through.
Otherwise, I know what you mean about the tin roof, we often lived in tents or cabins in the summer for two months on end...it was comforting knowing you were inside and the rain outside...though in backpacking trips, you weren't quite as well assured of the latter!
Is this to help you sleep now?
By the way, talking about the Feng Shui craze and the water sounds calming people down, I was working for over a year next to a courtyard in a big old fancy office building and the fountains were close to us, we'd crack open the window whenever possible, and it made quite a droning sound...then at 5 45 pm every evening they'd turn it off and everyone would breathe a great sigh of relief!
Never really knew if it was conducive to good work...
but it sure, well, made people use the facilities if you get my drift...
If not, see the Austiin Powers scene next to the fountain.
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I was born under a wandering star.