Hearing loss is caused by damage to one or more of the ear’s three regions:
- External ear, pinna, and ear canal
- Middle ear, which is separated from the ear canal by the eardrum
- Inner ear, which contains the cochlea, the main sensory organ of hearing
There are three main types of hearing loss, characterized by which part of the ear is damaged. These include:
There is also another area of hearing that can be affected, called Auditory Processing Disorder (APD), which is characterized by those individuals that hear well but do not process what they hear normally.
In conductive hearing loss, disorders in either the outer or middle ear prevent sound from passing into the inner ear. Voices and sounds may sound faint, distorted, or both. Conductive hearing losses are most often seen in young children, but they can also be seen in some adults. Most conductive hearing loss can be improved medically or surgically if treated promptly.
Causes of conductive hearing loss include:
- Infection of the ear canal or middle ear
- Fluid in the middle ear
- Perforation or scarring of the eardrum
- Ear wax (cerumen) build-up
- Dislocation of the three middle-ear bones, called ossicles
- Foreign objects in the ear canal
- Otosclerosis (abnormal growth of bone in the middle ear)
- Unusual growths in the outer or middle ear
In people who have sensorineural hearing loss, sound is efficiently sent to the inner ear, but some sort of damage to the inner ear interferes with proper hearing. This type of hearing loss occurs when there is either damage to the inner ear structures or the hearing nerve.
Sensorineural hearing loss is the most common type of hearing loss among adults It usually is not medically or surgically treatable, but can be treated successfully with hearing aids. Those who suffer from sensorineural hearing loss may complain that people seem to mumble, or that they hear—but don’t understand—what is being said. Aging is the most common cause of sensorineural hearing loss. As we get older, the sensory cells of the inner ear gradually die. Learn more about aging and hearing loss.
In addition to advancing age, sensorineural hearing loss can be caused by:
- Excessive noise exposure
- Viral infections (such as measles or mumps)
- Ototoxic drugs (medications that damage hearing)
- High fever
- Ménière’s disease
- Acoustic Neuroma (tumors)
If a hearing loss has both a conductive and a sensorineural component, it is referred to as a mixed hearing loss.
Hearing problems may also result from a central auditory processing disorder—a neurological problem that may be inherited or caused by complications during pregnancy, birth, or a combination of causes, such as head trauma, disease, tumor, and lead exposure, to name just a few. People with APD usually have normal hearing when taking traditional hearing tests, but they are unable to process speech effectively in everyday situations (classrooms, workplaces, community gatherings, etc.)
- What is Hearing Loss?
- Symptoms of Hearing Loss
- Causes of Hearing Loss
- Diagnosing Hearing Loss
- Degrees of Hearing Loss
- Treating Hearing Loss
- Preventing Hearing Loss