Enlarge ImageSensitive ears. Mice that received extra copies of a protein during fetal development produced more of a key hearing cell (bottom) than control mice did.Credit: David Woessner, John Mitchell, and John V. Brigande A cure for hearing loss could be closer, now that a team of scientists has produced key ear cells in mice--and for the first time verified that the cells work just like natural ones. The inner ear turns sound waves into electrical signals inside the organ of Corti, which is lined with rows of 15,000 to 20,000 hairlike cells. The cells respond to vibrations by...