I slept in a swamp last week, lot's of noisy frogs. I actually enjoyed the sound, so sleeping with it was no problem.
I remember a dream in which people were talking to each other, but they all made frog sounds instead of words, so I couldn't understand them.

So here's another sound that gets through to your brain while dreaming, but doesn't actually wake you up.

Could try playing a frog sound mp3 and do RC's everytime you hear a frog. But that's a lot like the hemi sync LD series, there they use the sound of rainfall.