Hearing loss is the reduced ability to hear sound. Deafness is the complete inability to hear sound. Deafness and hearing loss have many causes and can occur at any age. People can go deaf suddenly as a complication of a virus, or lose their hearing over time because of disease, nerve damage, or injury caused by noise. About 3 in 1,000 babies is born deaf, often because of genetic factors. Approximately 2 out of every 10 adults in Canada has at least mild hearing loss, and almost half of Canadians over 60 years of age have hearing loss.