As a biologist:
Nobody realize the capabilities of the human body and there aren't, and there won't be devices to improve what's already part of an astonishing machine. I must admit we are weak, but nothing will better than our own body. That's a joke.
(Our hearing range is limited by our physiology, not our neurons.) Dear Lord, let me give you an example: our running speed is limited by physiology, and our brain is wired to understand those signals, not more.
Babies can hear frequencies beyond 20khz. If you stimulate the nerves, the brain interprets the signals. The reason we don't hear higher frequencies is because it's being conducted through bone and interpreted by microscopic cillia that degrade as we age. There is nothing that points to us being unable to hear ultrasonic were our ears capable of transmitting it to our nerves.
It's incorrect to say our brains don't adapt past a certain age, they just aren't as malleable. Children can adopt to hemispherectomies better than adults for instance.
But for arguments sake, suppose that by automagical science, such a thing were possible. Would you go under the knife to have perfect audio for the rest of your life?
Edited by Kodhifi - 1/9/13 at 7:55pm