A number of conditions can exist that cause a disruption in the hearing process and lead to hearing loss. The two most common types of hearing loss are sensori-neural and conductive.

Sensori-Neural Hearing Loss Sensori-Neural, or "nerve" hearing loss, results from damage to the hair cells, nerve fibers or both, in the inner ear. This is the most common type of hearing loss and is often caused by aging or prolonged exposure to noise. It also can be caused by high fever, birth defects and certain drugs. People with sensori-neural hearing loss can hear speech, but frequently have difficulty understanding it. The problem is usually compounded when background noise is present. Sensori-neural hearing loss is most commonly treated by the use of a hearing instrument, and generally can not be corrected through surgery or medicine.

Conductive Hearing Loss Conductive hearing loss typically involves an obstruction in the outer or middle ear which reduces transmission of sound vibration through air, bone or tissue to the inner ear. Fortunately, many conductive hearing losses can be treated successfully by medical or surgical procedures. Hearing instruments can also successfully treat conductive hearing loss. Persons with both conductive and sensori-neural hearing loss are commonly referred to as having MIXED hearing loss. Most of these cases can be helped by either a hearing instrument or surgery.