Inside A Moving Car With Rain On The Window - 1 hour

It's the middle of the night, raining heavily, and you're sleeping in the back seat of a car that's driving on the motorway. (Windscreen wipers can't be heard :D).

This is a combination of rain on car windows and noise that I would say is nearing the brown and pink end of the noise-spectrum. It's very comforting and I hope soporific.