Sometimes, you need to block out unwanted noise--like when you're staying at a hotel and you can't get to sleep. There are some pretty effective sound machines now available, which sounds counter-intuitive since you're creating noise to block out noise. These machines provide white noise and/or ambient noise, that is, noises that generally peaceful and relaxing. Steadily falling rain and waves crashing on shore are two examples. But, do you really want to pack something else in your overnight bag?
Ambient-Mixer.com and sample sounds to your heart's content. For sleeping you may find exactly what you need in the category titled, "All sort of weather atmospheres." Try "Dreaming Rain" on for size!
You can also come to the Library to borrow Rainforest Magic a CD of ambient sounds, one of which is "Summer Rain" [CD MISCELLANEOUS RAI].