But these nerve hair sacs also happened to detect sound waves. As an unintended byproduct of balance hearing was born. When fish slithered onto land, their water hearing systems performed poorly in the air. In time, amphibians, reptiles, and birds developed better hearing, but not until mammals, did the outer ears appear, such as our own curved and folded half-shells of cartilage and flesh. And mammals alone have an inner ear with three separate chambers rolled up in a bone like a snail which captures a wide variety of sound.
Human hearing is tuned an octave lower for human voices.
But within our range we are masters. And with our brains we can understand sounds in ways unimaginable to other animals. Even birds can't hear other bird species' songs as well as we do. Our Sonic Environment and the Tuning of the World. One of the most evident testaments of this change is the way in which we have come to imagine God.