Types of Hearing Loss
Conductive Hearing Loss is the most common type of hearing loss in children, which occurs when the sound traveling through the external and middle ear is blocked or interrupted. Common causes for this type of hearing loss are ear infections, fluid in the middle ear, blockage of the ear canal by wax, or eardrum perforation. In individuals with conductive hearing loss, the inner ear functions normally, but the sound is not able to reach the cochlea. Although many conductive hearing losses respond to medical treatment, more serious causes of conductive hearing loss require surgical treatment in attempt to regain normal hearing. Hearing aids can also be effective in helping individuals with conductive hearing loss hear better.
Sensorineural Hearing Loss occurs when there is a problem in the inner ear (sensory) or the auditory pathways to the brain (neural). Sensorineural hearing loss can be inherited and present at birth. It may also be acquired later in life from a number of causes including noise exposure, bacterial and viral infections, and reactions to pharmaceutical drugs. Although many times the cause cannot be determined with certainty. Sensorineural hearing losses are generally permanent and not correctable through medical or surgical interventions. Sensorineural hearing loss is not uncommon. In most individuals with this type of hearing loss, the fitting of audiologically appropriate amplification is the most immediate and successful solution.
Mixed Hearing Loss describes the presence of a conductive and sensorineural hearing loss at the same time. An example might be a individual with moderate sensorineural hearing loss whose hearing is made worse by the presence of fluid in his middle ear. The hearing in individuals with mixed hearing loss will not likely return to normal levels following the resolution of the conductive component. Depending on the degree of permanent sensorineural hearing loss, these individuals may benefit from the use of hearing aids.
Central Auditory Dysfunction is applied to numerous types of hearing impairments caused by dysfunction or abnormality of the auditory nerve pathways or the auditory processing within the brain. Also termed "neural" hearing impairment, the damaged pathways can be identified through advanced testing procedures. A large portion of those identified to have Central Auditory Dysfunction show communication disorder symptoms, such as difficulties in understanding speech even without hearing loss.
Auditory Neuropathy Spectrum Disorder is a relatively new auditory disorder. Affected individuals typically have near-normal hearing but have difficulty understanding speech, especially in the presence of background noise. Advance testing procedures may identify abnormal auditory pathway processing, and parents sometimes complain that their children seem to have "good hearing days" and "bad hearing days." The range of this disorder is vast: some individuals experience little or no difficulties in hearing and understanding in spite of abnormal test results, while others complain of "hearing but not understanding." Auditory neuropathy may overlie other types of hearing loss and its management and treatment are not always clear. Some success with children with this disorder has been achieved with hearing aids use or cochlear implantation.