There are three distinct types of hearing loss: conductive, sensorineural and mixed. Conductive hearing loss is caused by a problem with the outer or middle portion of the ear; sensorineural is caused by an issue with the inner part of the ear. Mixed hearing loss is caused by a combination of the two.In order to hear, a sound wave is captured by the outer ear, funneled down the ear canal and hits the eardrum. This causes a vibration, which is passed through three small bones within the middle ear; together, these bones are known as the ossicles. The last bone in the ossicle series hits the oval window, located within the cochlea. The cochlea is filled with fluid and lined with tiny hairs. When the oval window is hit, this causes the fluid within the cochlea to move. The movement of the fluid causes the tiny hairs lining the cochlea to move as well. When these hairs move they create an electrical signal. This signal is passed through the auditory nerve to the brain; the brain is able to interpret this signal as sound.
Conductive hearing loss is caused by a problem capturing or transferring the sound wave from the outside world to the inner ear. This can be caused by fluid within the middle ear, a perforated eardrum, impacted earwax or a malformation in the outer or middle portion of the ear. This type of hearing loss is usually temporary and can commonly be treated through medical or surgical means.
Sensorineural hearing loss is caused by a problem within the inner ear or the auditory nerve. This is the most common type of hearing loss and is usually permanent. It can be caused by exposure to a loud noise, head trauma, aging or a virus or disease. Fortunately, even though this type of hearing loss cannot be corrected it is usually able to be treated with a hearing aid.
Mixed hearing loss is caused by a problem with the outer or middle ear and the inner ear. Typically, the cause of the conductive hearing loss is identified and treated first then the sensorineural is addressed.