If you’re like most people, you take hearing for granted. But the hearing process is actually quite complex.
The Hearing Process
The ear is made up of three separate sections: the outer ear, middle ear, and inner ear. All three work together to help you hear.
The outer ear, also known as the auricle or pinna, is the visible external portion. This is where hearing begins; sound waves enter the outer ear and are channeled down the auditory canal to the eardrum, or tympanic membrane.
The eardrum marks the beginning of the middle ear. Sound waves that have traveled through the auditory canal cause this structure to vibrate, which stimulates movement of the ossicles – three tiny bones referred to as the hammer, anvil and stirrup. Sound is amplified in the middle ear, and the movement of the ossicles helps transmit vibrations into the inner ear.
The inner ear houses the cochlea, a fluid-filled organ that converts sound waves into electrical impulses through stimulation of tiny hair cells. These impulses pass through the auditory nerve to the brain, where they are interpreted as sound. This is how you hear!
Hearing Loss Categories
Hearing loss is categorized according to which portion(s) of your ears are damaged. Injury or disease that affects the outer ear or middle ear results in conductive hearing loss. This type of hearing loss can sometimes be reversed with medication or surgery. Damage to the inner ear causes sensorineural hearing loss (often called nerve deafness). This occurs when the hair cells in the cochlea have been damaged, and may be the result of trauma, disease, aging, genetics or ototoxic medications. About 90% of patients with hearing loss suffer from this type. It cannot be cured, but usually responds well to hearing aids.
Occasionally, patients will suffer from damage to both the inner and outer or middle ear. This is known as mixed hearing loss.