Cox lab studying nov el gene to learn why hearing cells die Hearing loss is primarily caused by death of sound-sensing cells called hair cells, which are found in the inner ear, in the snail-shaped structure called the cochlea. These cells can naturally regenerate in birds, frogs and fish, allowing recovery of hearing. However, hair cells were not thought to regenerate in humans or other mammals until very recently. In 2014, Brandon Cox, PhD, discovered their ability to spontaneously regenerate in newborn mice. Cox is an assistant professor of pharmacology and a research scientist at Southern