Hearing Loss Types & Hearing Loss Causes
How Hearing Works: The ear has three main parts or sections – the outer ear, middle ear, and inner ear. Each section has a specific function that allows sound waves that enter the ear to be transformed into electrical impulses that the brain can understand. The outer ear collects sound waves and directs them to the middle ear. The middle ear then amplifies the sound and transmits it to the inner ear. The inner ear converts the sound vibrations into electrical impulses that travel along the auditory nerve to the brain.
The outer ear catches sound waves and directs them into the ear canal. The ear canal carries the sound waves to the eardrum (tympanic membrane). Sound waves cause the eardrum (tympanic membrane) to vibrate. The bones in the middle ear (malleus, incus, and stapes) pick up these vibrations. Vibrations pass through the oval window to the cochlea, setting the fluid inside in motion. This causes special nerve cells to turn the sound waves into electrical impulses. The auditory nerve sends these electrical impulses to the brain where they are heard as sound.
Conductive hearing loss:
Conductive hearing loss is caused by damage to the outer or middle ear. With a conductive loss, sound waves are blocked as they move through the outer or middle ear. Since the sound cannot be conducted efficiently, the sound energy that reaches the inner ear is weaker or softer. A conductive loss can result from infection, excessive earwax buildup, fluid in the middle ear, damage to the middle ear bones, and perforation of the eardrum or foreign body in the ear canal.
Sensorineural hearing loss:
A sensorineural is caused by damage to the inner ear. Sound waves travel normally through the outer and middle ear, however, the inner ear is unable to pick up the vibrations or is unable to send the vibrations to the brain. Also called “nerve deafness”, it usually occurs in both ears. Sensorineural loss can result from infection, disease, certain drugs, excessive noise, birth defects, and aging.