There are THREE major types of hearing loss:
- 1. Conductive
- 2. Sensorineural
- 3. Mixed
Conductive Hearing Loss
This occurs when sound waves are prevented from entering the inner ear due to difficulties in the outer ear canal or the middle ear. Individuals with conductive hearing loss will hear sounds perfectly if they are made loud enough to overcome the difficulty in the outer or middle ear. Medical or surgical intervention can improve a conductive hearing loss. Common causes of conductive losses are ear wax plugging the outer ear canal; fluid in the middle ear that inhibits the vibration of the ear drum (eustachian tube dysfunction); damage to the ear drum or middle ear bones caused by trauma, infection, or tumors; or abnormal bone growth that restricts the vibration of the middle ear bones (otosclerosis).
A person with a conductive hearing loss may notice that their ears may seem to be full or plugged. This person may speak softly because they hear their own voice quite loudly. Crunchy foods, such as celery or carrots, sound very loud and this person may have to stop chewing to hear what is being said. All conductive hearing losses should be evaluated by an audiologist and a physician to explore medical and surgical options.
Sensorineural Hearing Loss
Also referred to as nerve deafness, usually results from a loss of hair cell function inside the cochlea (inner ear – see picture above). Sound waves are delivered to the inner ear, but due to missing or damaged hair cells, impulses are not delivered to the brain. For this reason, sound is not perceived. Individuals with sensorineural hearing loss will hear sound, but it may seem distorted. Often people with this type loss will say, “I can hear people talking. I just don’t understand what they are saying.” Hearing aids can help improve understanding of speech for individuals with sensorineural hearing loss. Common causes of sensorineural losses are noise exposure, aging, infection, or genetic defects. Additionally, abnormal fluid pressure in the inner ear can cause a sensorineural hearing loss. Examples include Meniere’s disease, too much inner ear fluid pressure, a perilymph fistula (a hole in the cochlea), or too little fluid pressure. Occasionally, a small benign tumor (acoustic neuroma) may be pressing on the auditory nerve causing hearing loss.
Sensorineural hearing loss is the most common type of hearing loss. More than 90 percent of all hearing aid wearers have sensorineural hearing loss. The most common causes of sensorineural hearing loss are age related changes and noise exposure. A sensorineural hearing loss may also result from disturbance of inner ear circulation, increased inner fluid pressure or from disturbances of nerve transmission. Sensorineural hearing loss is also called “cochlear loss,” an “inner ear loss” and is also commonly called “nerve loss.” Years ago, many professionals said there was nothing that could be done for sensorineural hearing loss – that is totally incorrect today. There are many excellent options for the patient with sensorineural hearing loss.
Mixed Hearing Loss
This occurs when there is a difficulty in the outer/middle ear that prevents sound from entering the inner ear, in addition to a loss of transmission of electrical impulses to the brain from the inner ear (usually due to problems with hair cells). Even when sounds are made loud enough to overcome the conductive portion of this hearing loss, individuals will still have difficulty understanding speech due to the sensorineural portion of the hearing loss. Medical or surgical intervention can improve the conductive portion of the hearing loss and a hearing aid can help improve understanding for the sensorineural portion of the hearing loss.