That's a cool idea. I'd be interested, although by the measure of where I have useful ideas, I should instead listen to a recording of a shower. A very calming form of white noise, although it could precipitate increased restroom usage.

I often get into the groove of the sonic landscapes at Quiet American's One Minute Vacations and wish for longer versions:

http://www.quietamerican.org/vacation.html

There is one link there to a streaming server that serves up a long-form field recording for your testing:

http://69.64.229.114:8000/