I'm in Bali right now and am finding out all sorts of things I never knew before. Last night there was a gecko (about 3 inches long) on the ceiling of our hotel room. After the lights were turned off I heard a very loud sound and finally realized it was the gecko doing a bit of vocalizing. I'd assumed that these little creatures were voiceless. It sounded like it was saying "gecko, gecko". It sounded just like this video I found on You Tube.