Causes of Hearing Loss
The simple act of hearing is anything but simple. Hearing is a complex process that involves several specialized structures within the ear and brain. As such, hearing loss can occur at any number of places.
The causes of hearing loss can be divided by their location, namely the outer ear, middle ear, or inner ear. The outer ear is the “ear” that you see, also called the auricle, plus the ear canal. The inner ear includes the eardrum (tympanic membrane) and the small ossicles (hammer, anvil, and stirrup). The main structure in the inner ear involved in hearing is the cochlea.
Hearing loss in the outer ear
One of the most common and easily treated causes of hearing loss involving the outer ear is the buildup of earwax (cerumen). Some people produce excessive amounts of earwax that does not properly clear from the ear canal. Likewise, people trying to clean their ears with cotton swabs tend to push the earwax towards the eardrum and compact it. This earwax physically blocks the ability of sound waves to reach the eardrum.
Other substances may block the ear canal and interfere with hearing. Serious infections, bony or tissue growths (polyps) or even small tumors can block the ear canal and cause hearing loss.
Hearing loss in the middle ear
The most common cause of middle ear hearing loss is otitis media or middle ear infection. Fluid builds up behind the eardrum to prevent it from moving freely, which decreases its ability to transmit sound waves.
Other forms of infection may interfere with the function of the Eustachian tube, a tube that connects the middle ear to the throat. This tube normally balances air pressure in the middle ear (the reason your ears may “pop” when you yawn). When the Eustachian tube is inflamed, too little or too much air pressure may build up behind the eardrum and prevent it from moving properly, leading to decreased hearing.
It is not common to develop small or even large holes in the eardrum (tympanic membrane perforation). The hole in the eardrum obviously affects its ability to transmit sound waves.
Less common causes of hearing loss within the middle ear include cholesteatoma, paraganglioma, and otosclerosis.
Hearing loss in the inner ear
Hearing loss that affects the inner ear is sometimes called sensorineural hearing loss because it involves the cochlea (a sensory organ) and/or the nerves and brain. Not surprisingly, diagnosing and treating hearing loss that occurs within the inner ear is challenging.
Perhaps the most common cause of inner ear hearing loss is age-related hearing loss (presbycusis). It is progressive, occurs equally in both ears, and usually affects high-frequency sounds more than low-frequency sounds. People with age-related hearing loss often notice that they have problems understanding speech in a noisy environment.
Meniere disease affects the inner ear but causes more problems than simply hearing loss. In addition to hearing loss, people with Meniere disease usually experience prolonged vertigo, a fullness in the ears, and ringing in the ears.
The hair cells within the cochlea are very sensitive structures, both to sounds and to substances. Prolonged exposure to loud noises, certain drugs or environmental toxins, and metabolic diseases can impair or destroy cochlear hair cells. In some cases, this damage can lead to permanent hearing loss.
If you think you may be experiencing hearing loss, the first step is to schedule a hearing screening. Your audiologist can perform a simple, painless test that will identify if you have any hearing loss. Moreover, your audiologist has the expertise and resources to pinpoint the location of your hearing loss and help develop a comprehensive treatment strategy.