Sensorineural Hearing Loss
Just as farsightedness is often age-related, sensorineural hearing loss (SNHL) also occurs as a natural part of growing old; it accounts for about 90% of all hearing loss.
SNHL is commonly caused by damage to the inner ear (the cochlea), or by damage to the nerve pathway from the inner ear to the brain. As a result, signals reaching the brain lack vital auditory information, making speech unintelligible and sounds inaudible.
Apart from aging, SNHL may also be caused by exposure to loud sounds, head injuries, genetics, diseases, tumors, and certain powerful medications. People who have both conductive and sensorineural hearing loss are said to have a mixed hearing loss.
Fortunately, hearing instruments can help.
Conductive Hearing Loss
Have you ever plugged your ears with cotton wool so that you can fall asleep despite street noise, or can work despite office chatter? If so, you have experienced a hearing impairment similar to what is called conductive hearing loss.
In such type of hearing impairment, a mechanical problem in the outer or middle ear interferes with the transmission of sound waves to the inner ear. Excessive earwax, infections, a perforated eardrum, and any stiffening of or disruption to the three middle ear bones (the ossicular chain) can result in conductive hearing loss.
Usually, medical intervention can help to resolve conductive hearing loss; when this is not possible, hearing instruments can help. People who have both conductive and sensorineural hearing loss are said to have a mixed hearing loss.