Sensory hair cells(聴覚細胞、有毛細胞)in the cochlea(内耳の蝸牛)and inner ear are crucial to the hearing process, converting sound waves into the electrical impulses that are sent to the brain. Damage to these cells is the most common cause of hearing impairment. Prolonged exposure to loud noise, as well as infections(感染), aging, and genetic diseases, can lead to the loss of these cells. In most adults, damaged hair cells do not regenerate(再生する), but researchers using gene therapy on mouse embryos have been able to grow the hair cells, leading many to hope that nerve deafness may one day be curable.