Most common cause of bilateral hearing loss in old age is called presbyacusis. This means gradual weakening of the nerve of hearing due to age. This condition may also present with ringing sensation in the ear. This can be treated by using hearing aids.
Long term untreated middle ear infection, can damage the tiny bones responsible for hearing and cause hearing loss. This can be treated by a surgery called as Tympanoplasty which involves repair of the ear drum as well as the middle ear bones.
Otoslcerosis is a condition that involves stiffening of the middle ear bones. This presents as gradual decease in hearing. It is more common in women and may occur soon after pregnancy and delivery.
This condition can be treated by a surgery called as stapedotomy.