Many people have partial or complete loss of hearing, a condition known as deafness.
There are many causes of deafness. Deafness that is congenital or from early infancy often interferes with the ability to learn spoken language, although signed language is not affected. Deafness that comes later in life usually does not result in poor speech, but may induce the deaf person to become isolated, affecting mental wellbeing. One out of three persons over the age of 65 experiences hearing loss as a part of ageing. Sounds become muffled, causing the listener to ask people to speak louder.