There are two main types of deafness; sensorineural deafness and conductive deafness. The first is caused by damage to sensory part of the ear or the auditory nerve. The second is caused by blockage of the sound waves between the source of the sound and the sensory part of the ear.
Examples of sensorineural deafness include loss of with hearing with age (presbyacusis). Also in this group are noise-induced hearing loss and Meniérès disease. These are mostly irreversible. Examples of conductive hearing loss include accumulation and impaction of ear wax. Also surfers' ear and a foreign object stuck inside the ear canal, like a pea. A perforated tympanic membrane is another cause.
Conductive causes of hearing loss are, on the whole, reversible. Wax and foreign bodies can be removed. Surfers' ear can be operated on with excess bone being removed and perforated ear drums heal. They are also mostly avoidable by looking after your ears and wearing ear plugs to protect you from cold water whilst surfing and sea swimming. Ear plugs are also excellent at preventing noise induced hearing loss so are able to prevent several causes of hearing loss. Antibacterial varieties like ZenPlugs are ideal as they will protect against ear infections and otitis also. Swimmers' ear is a commonly experienced disorder causing ear pain and discomfort.