There are three major parts to the ear: the outer ear, middle ear and inner ear. The outer ear is the part we see, including the ear canal. The middle ear includes the eardrum, which is technically called the tympanic membrane. It also includes the three bones or ossicles of the middle ear and the eustachian tube. The eustachian tube leads to the throat and helps equalize pressure in the middle ear. The inner ear includes the cochlea, which looks like a snail shell, and the semi-circular canals. Inside the cochlea are sensory cells which look like fine hairs and respond to sound then send nerve signals to the brain. The semi-circular canals help us maintain our balance.

Conductive hearing loss occurs when the structures of the outer or middle ear don't work correctly. This type of hearing loss is more likely to respond to medical or surgical treatment. Sensorineural hearing loss is linked to problems of the inner ear structures, and is sometimes called "nerve deafness." Mixed hearing loss occurs when someone experiences both types of hearing loss.