The anatomy of hearing and hearing loss

Are you concerned that you may be experiencing hearing loss? Understanding the different ways that hearing loss may occur can help move you toward a valuable diagnosis. Here’s what you need to know about your ears and how they work.

Your ears and hearing

There are three major sections of the ear: the outer ear, the middle ear, and the inner ear. Working together, these components collect sounds from the world, process them, and send signals to the auditory regions of your brain. While each section of the ear serves a distinct function, each is also vulnerable to certain problems and disorders.

Any time the normal path of sound is interrupted or impeded in some way, hearing may be affected. An interruption can occur at any section of the ear and hearing losses are classified based on where the interruption occurs.

Problems with the middle and outer ear

The outer ear, made of cartilage and skin, is the part you can see. The middle ear lies inside from the eardrum, which is tucked into the ear canal, and contains three tiny bones that transmit sound waves to the inner ear. These bones, known collectively as the ossicles, are the malleus, incus, and stapes (also called the hammer, anvil, and stirrup).

When hearing loss occurs due to problems with the outer or middle ear, it is usually classified as a conductive loss. That means the outer or middle ear cannot properly conduct or transmit sound, resulting in reduced sound volume and imperfect hearing. Fortunately, conductive hearing loss is usually temporary and can often be corrected with proper treatment. Treatment will depend on the cause, and there can be many different reasons for conductive hearing loss. These include:

Impacted earwax

Everyone produces a certain amount of earwax, which helps protect the ear canal from dirt and infection. But too much wax can lead to a blockage and impaired hearing. Problems associated with the accumulation of wax are one of the most common reasons people seek medical treatment for their ears.

In most cases, wax can be removed at home by placing a few drops of mineral oil, baby oil, glycerin, or over-the-counter wax-softening drops in the ear. If repeated home-care attempts fail, a healthcare provider (HCP) can prescribe stronger eardrops. An HCP may also attempt to remove stubborn wax using irrigation, suction, or a syringe.

Warning: Never use a cotton swab to remove earwax. Doing so is likely to pack more wax in. People with a history of middle ear infections, swimmer's ear, or a hole in the eardrum should not treat impacted earwax themselves.

Infection

Otitis media, a common infection of the middle ear, is more prevalent in children, but adults can experience it as well. A variety of viruses and bacteria can cause these infections, and people often get them after having a cold. Whatever the cause, a buildup of fluid in the middle ear cavity can lead to hearing loss. Although it is usually temporary, it may lead to permanent hearing loss if left untreated, especially as a person gets older.

Frequent hand washing is an easy way to avoid viruses and related respiratory complications that can lead to otitis media. If you experience pain, itching, or drainage from the ear, or if you have a fever, nausea, and diarrhea, call your HCP. This type of infection is usually treated with antibiotics.

Perforated eardrum

Head trauma or infection can cause a hole or rupture in the eardrum, which impairs hearing. The size and location of the hole affect the degree of hearing loss. A swift blow to the ear with a cupped hand, an explosion or gunshot near the ear, or a foreign body like a rogue cotton swab also can perforate the eardrum. Trauma to the ear or head can also cause the ossicles to fracture or become disjointed. This can break the chain of sound conduction to the inner ear, causing irregular hearing, like echoes or murmurs.

Most eardrum perforations heal on their own within a few weeks, but larger perforations may require surgery or patching by an HCP.

Problems with the inner ear

Adjacent to the middle ear is the inner ear, which is tucked into a small space in the bone of the skull. The inner ear contains two main parts, which control hearing and balance. The cochlea, which controls hearing, is shaped like a snail and consists of fluid-filled chambers lined with small hairs that vibrate and send electrical impulses to the brain. Your sense of balance is managed by a pair of structures known as the semicircular canals. Running from the inner ear to the brain is the auditory nerve.

Damage to or death of the hair cells of the inner ear or the nerve pathways to the brain account for 90 percent of all hearing loss. Known as sensorineural hearing loss or nerve deafness, this is the most common cause of progressive hearing loss.

Individuals with this impairment not only have trouble hearing faint sounds but may also have difficulty understanding speech or hearing speech clearly. This type of hearing loss is usually permanent. The human body cannot regenerate the sensory receptor hair cells.

Some people with this type of hearing loss may benefit greatly from hearing aids. And adults with severe hearing loss due to cochlear problems or age-related disease may be considered candidates for a cochlear implant, a small electronic device that can be surgically implanted to help restore some hearing.

Scientists are also exploring how gene manipulation, gene therapy, and stem cell transplantation may also help repair or replace damaged cochlear hair cells in humans.

Sensorineural hearing loss includes the following:

Age-induced hearing loss

Most sensorineural hearing loss stems from age-related changes to the ear. As people grow older, changes to the inner or middle ear or to the nerve pathways leading from the ear to the brain cause a gradual but steady loss of hearing, known as presbycusis. There is some debate over why these inner ear changes happen with age, but it may be because the structures within the ear gradually lose blood flow over time.

Symptoms of age-related hearing loss include:

• The speech of others sounds mumbled or slurred
• High-pitched sounds are harder to understand
• Background noise makes listening difficult
• Certain sounds seem overly loud or annoying
• There is ringing, hissing, or roaring in the ears (also known as tinnitus)

Although there is no way to prevent or slow down age-related hearing loss, you can avoid compounding the problem by taking good care of your ears, treating wax buildup properly, and protecting your ears from further damage, such as from excessive noise. Certain chronic health conditions, such as heart disease, diabetes, or high blood pressure, can provoke changes in the blood supply to the ear and potentially lead to hearing loss. Managing these conditions or preventing them with a healthy lifestyle will help protect your hearing as well.

Noise-induced hearing loss

Excessively loud noise can cause irreparable damage to the hair cells of the inner ear. Noise-induced hearing loss can result from one-time exposure to a sudden loud noise, like a gunshot or an explosion, or from long-term exposure to elevated noise levels in the home or workplace.

To protect your ears from noise, you should know when they’re in danger. Loudness or intensity of sound is measured in units called decibels (dB). A normal conversation falls somewhere near 60 dB, while city traffic chimes in at about 80 dB. Anything over 80 to 85 dB could damage your ears. Prolonged exposure to sound levels above 90dB can lead to permanent hearing loss.

Protect your ears with earplugs or earmuffs during noisy activities and turn down the volume on your smartphone or television to the lowest level necessary.

Medication-induced hearing loss

Certain medications, including antibiotics, chemotherapy medications, anesthetics, heart medications, and mood-altering drugs are known to be damaging, or ototoxic, to the ears. Problems caused by an ototoxic medication tend to develop quickly. Ringing in the ears (tinnitus), hearing loss, and vertigo are usually the first signs.

The symptoms of medication-induced hearing loss are usually temporary and hearing returns to normal once the person stops taking the medication. Some medications, however, can cause permanent damage to the inner ear, resulting in hearing loss even if you stop taking the medication. Speak with your HCP about alternative medications if you are concerned about ototoxicity.

Researchers are exploring whether administering antioxidant drugs along with certain medications can protect the inner ear from medication-induced hearing loss. If you have concerns about your hearing, or you experience hearing loss due to a medication, discuss your prescription and over-the-counter medications with your HCP or pharmacist.

Seeking help for hearing loss

The longer you live, the greater the chances you will experience some reduction in your ability to hear. One in three people between the ages of 65 and 74 and nearly half of people over 75 have some difficulty hearing. If you or the people who love you suspect you may have developed a hearing problem, reach out for a consultation with an HCP.

They can check for wax in the ear canals, infection, or other treatable conditions. If hearing loss is suspected, your HCP may do initial screening tests in the office. If these initial tests suggest or reveal hearing loss, a more thorough hearing test or audiologic evaluation may be done to assess whether you have hearing loss and how to manage it, which could include getting hearing aids.

Ignoring a potential problem could lead to irreversible damage to your ears—but catching issues early may help you maintain your hearing.