I have never been able to find a spring peeper. This is frustrating as their sound seems to come from every pond or damp spot on a spring evening. The location of their eyes on the top of their head means they are very hard to sneak up on. This is similar to the "eyes in the back of their head" reported in mothers and 5th grade teachers.
I had never thought about the fact that they produce sounds like a harmonica player, with air going both in and out over their vocal cords. They are even able to make sounds under water as the air moves back and forth while their mouth is closed.
"A male toad or frog produces its call by moving air rapidly back and forth over its vocal cords. When calling, the animal closes its mouth and nasal openings. Then it forces air from its lungs into the mouth cavity then back into the lungs, each time passing over the vocal cords."Click on the "more" under the "Frog and Toad Facts" to learn about the differences between them. Although it doesn't mention the Ozark legend of "fine as frog hair," it describes frog's tiny teeth on both jaws which are lacking on toads.