Morbidity 1/1000 in new born baby 1/100 in younger 14/100 in middle age 30/100 in 65-75 year old(presbycusis) 50/100 in >75 year oldMorbidity ◼ 1/1000 in new born baby ◼ 1/100 in younger ◼ 14/100 in middle age ◼ 30/100 in 65-75 year old (presbycusis) ◼ 50/100 in >75 year old