Types of Hearing Loss
How do we hear?
Sound travels in waves. These waves are collected by the outer ear and sent through the external auditory canal (also called the ear canal) to the eardrum.
When sound waves hit the eardrum, the waves create vibrations that cause three ossicles (bones) in the middle ear to move. These bones are called the malleus, the incus, and the stapes (also known as the hammer, anvil, and stirrup).
The smallest bone, the stapes, moves the oval window between the middle and inner ear. When the oval window moves, fluid in the inner ear sends vibrations to the cochlea.
Within the inner ear, thousands of tiny hairs move as the fluid inside the cochlea moves. The movement of these hairs sends signals through the auditory nerve to the brain. The hearing center of the brain then translates these movements into sounds that we recognize.
What are the different types of hearing loss?
Conductive hearing loss
This type of hearing loss occurs when there is a problem in the outer or middle ear. Sound is not able to travel properly through the ear canal to the eardrum and ossicles.
One of the most common causes of conductive hearing loss is fluid or wax in the ear. These may lead to a temporary hearing loss that can be treated by a doctor.
Children with conductive hearing loss usually cannot hear faint sounds. Conductive hearing loss can often be medically or surgically corrected.
Conditions associated with conductive hearing loss include:
- Fluid in the middle ear from colds or allergies
- Otitis media (middle ear infections)
- External otitis (infections of the ear canal)
- Perforated eardrum
- Impacted earwax (wax that will not easily come out of the ear)
- Foreign objects within the ear
- Absence (loss) or malformation (unusual shape) of the outer ear, middle ear, or ear canal
Sensorineural hearing loss
This type of hearing loss occurs when there is a problem in the cochlea (part of the inner ear).
Patients with sensorineural hearing loss can have a varying amount of hearing loss (slight to profound) and may have difficulty hearing and understanding speech clearly.
Sensorineural hearing loss is typically treated with the use of hearing aids or other hearing technologies; it cannot be medically or surgically corrected. While this type of hearing loss is permanent, most children will benefit from hearing aids or other hearing technologies, along with hearing therapy.
Conditions associated with sensorineural hearing loss include:
- Certain viruses (such as cytomegalovirus or rubella)
- Certain diseases (such as toxoplasmosis)
- Birth complications (including babies who weighed less than 3 pounds at birth, needed to stay in the neonatal intensive care unit, or needed blood transfusions)
- Drugs that are toxic to the auditory (hearing) system
- Certain genetic syndromes (for a list of genetic conditions associated with hearing loss, please click here.)
- Exposure to noise
- Head trauma
- Aging
- Tumors
Mixed hearing loss
This type of hearing loss occurs when a child has both conductive hearing loss and sensorineural hearing loss. People with mixed hearing loss may have damage to the outer ear, the middle ear, the inner ear, and/or the nerve that connects the inner ear and the brain.
Auditory neuropathy (also called auditory neuropathy/auditory dys-synchrony)
This type of hearing loss occurs when sound enters the inner ear normally, but is not sent from the inner ear to the brain correctly. People with auditory neuropathy may have normal hearing or hearing loss, and usually have trouble understanding speech. Auditory neuropathy can affect people of all ages. A very small percentage of people with hearing loss have auditory neuropathy.
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