Dog's Keen Sense of Hearing

Does your dog ever stop at the door and change his mind about going outside if it's raining?  My dogs, Bella and Chief, do it nearly every time it rains - hard or light. I thought they were wimps. Instead, I just learned that the rain, being water of course, amplifies sounds and can hurt their very sensitive ears.
Amazing!  Unfortunately, it doesn't explain why Bella's barking doesn't cause her excruciating pain.