Uppsala University Ear membrane and auditory nerve in the cochlea. Humans can perceive frequencies from 20 Hz (the top of the coil) to 20,000 Hz (the base of the coil). Credit: Hao Li Photograph: Hao Li Researchers at Uppsala University have created the first 3D map of the hearing nerve showing where the various sound frequencies are captured. Using what is known as synchrotron X-ray imaging, they were able to trace the fine nerve threads and the vibrating auditory organ, the cochlea, and find out exactly how the frequencies of incoming sound are distributed. “This can make treatment with cochlea implants for the hearing-impaired more effective,” says Helge Rask-Andersen, Professor of Experimental Otology at Uppsala University.