Conductive hearing loss occurs when your outer ear, middle ear or ear canal has become blocked or damaged. This can make it hard for sounds to pass effectively from the outer ear to your middle ear.
Conductive hearing loss is less common, affecting only 10% of all hearing loss.
Conductive hearing loss is considerably less common than sensorineural hearing loss, making up just 10% of cases of hearing loss.
Have you ever been on a flight and your ears start to feel clogged? This will have been caused by the sudden change in altitude and the air pressure outside of your body being different from that in your middle ear and Eustachian tubes. The Eustachian tubes are canals located on either side of your face that runs from the back of your nose and upper throat to your middle ear. When the change in air pressure makes your ears feel clogged and your hearing becomes muffled, this is similar to conductive hearing loss linked to Eustachian tube dysfunction. This is one of the common causes of conductive hearing loss.
The anatomy of your ear is made up of:
The outer part of your ear directs sound onto your eardrum (tympanic membrane) and then these sounds are transmitted as vibrations through your middle via small ear bones before finally reaching your inner ear (cochlea).
Conductive hearing loss is usually mild to moderate and makes sounds seem softer. However, when amplified, they can be heard more clearly. You may be able to hear better when you are in a noisy environment because conductive hearing loss reduces background noise that would otherwise interfere with the conversations you want to listen to. If you were to put cotton wool in your ears or wear earplugs, this will be similar to what conductive hearing loss can sound like.
There are several causes of conductive hearing loss from something relatively common as impacted ear wax to other rarer causes such as cholesteatoma.
Impacted ear wax (cerumen): A relatively common cause of temporary conductive hearing loss, impacted earwax is the build-up of excess wax in your ear. It can be made worse if you try to dislodge the earwax from the ear canal yourself with a cotton bud. The excess wax can stop sound from reaching your inner ear from your outer ear.
Infection of the outer ear (otitis externa): This is an infection of the skin of the external ear canal. When the debris and swelling block the canal it can lead to conductive hearing loss.
Squamous cell carcinoma: Squamous cell carcinomas of the temporal bone is the most common cancer of the external ear canal and usually affects people in their 50s and 60s. Discharge from the ear is the main symptom, while earache, bleeding and conductive hearing loss are also quite common.
Blocked Eustachian tube: The Eustachian tube links the back of your nose to the middle ear. You may experience Eustachian tube dysfunction when there is swelling to the mucosal tube lining or the tube is unable to open or close correctly. It’s common to experience temporary dysfunction during flights or when you have a head cold or fluid in the ear (swimmer’s ear).
Perforated eardrum: Trauma or infection in the ear can lead to a hole developing in your eardrum. This can cause you to have reduced hearing in the affected ear. Inserting something like a cotton bud too far into your ear, exposure to very loud noises (noise-induced hearing loss), head trauma, blow to the ear or changes in air pressure (barotrauma) that occur during a flight or while scuba diving can cause a perforated eardrum.
Infection (otitis media): Inflammation can affect your middle ear. Chronic suppurative otitis media is a persistent ear infection that causes perforation or tearing of the eardrum. Otitis media with effusion (fluid in the middle ear) is the most common type associated with hearing loss, vertigo, tinnitus (ringing in the ears) and earache. Otitis media is more common in adults with weakened immune systems.
Otosclerosis: This is a rare, abnormal growth of one of the very small bones located in the middle ear (stapes bone) and stops the structures in your ear working properly. It’s supposed causes are genetic, inflammatory, hormonal and metabolic. It mainly affects peopled aged 15 to 40 and twice as likely to affect women than men. Around 20% of conductive hearing loss cases are attributed to otosclerosis, according to a 2009 study.
Cholesteatoma: More commonly linked with infections, these abnormal, noncancerous skin growths develop behind the eardrum in your middle ear. They often develop as a sac or cyst and linked to chronic ear infections. As the size of the growth increases, it can damage the very delicate bones in the middle ear.
Paraganglioma: Sometimes referred to as glomus tympanicum, this is the most common primary neoplasm of the middle ear. It’s also the second-most-common tumour of the temporal bone. It’s more common for it to affect women in their 50 and 60s. It causes tinnitus (ringing in the ears) but the mass in the middle ear can also stop sound waves passing through the middle ear to your eardrum, causing conductive hearing loss.
Temporal bone trauma: Blunt head injuries (such as from a car accident) can damage the middle ear and eardrum and injure the brain, facial nerves and inner ear. Patients who are conscious following the injury will immediately experience hearing loss and this is often the most common complaint they report after temporal bone trauma. Around 40% of people with head injuries experience hearing loss and tinnitus.
Several tests will diagnose conductive hearing loss. Further tests are used to diagnose any underlying diseases that could lead to conductive hearing loss.
Otoscopy: This is a common test used to diagnose conductive hearing loss. It involves your doctor gently inserting an otoscope into your ear so they can examine your ear canal and eardrum. It will help them to determine if there is an injury to your eardrum, a problem in the middle or foreign bodies in your ear canal such as impacted earwax. Your doctor will examine the colour of your eardrum, its translucency to see whether it’s opaque or transparent and its position to see whether it’s bulging, retracted or neutral.
Weber test: This test using a tuning fork which is placed on the crown of your head. You will be asked if the sound is louder in your left ear, right ear or the middle. If your hearing is normal, then you will be able to perceive the sound equally in both ears. However, if you have conductive hearing loss in just one ear, then you will likely hear the sound louder in that affected ear.
Tympanometry: This uses a probe-like device which is placed in your ear to determine if there is any abnormal pressure, fluid or a growth in your middle ear. It will also be used to see if there is any perforation or scarring to your eardrum or any issues with the small bones of your middle ear. The test is very quick and only takes two minutes for each year. However, you cannot speak, move or swallow while the test is being carried out.
Pure-tone audiometry: This test is used to assess the threshold of a person’s hearing and to determine if their hearing falls within or below normal limits.
While sensorineural hearing loss is permanent, conductive hearing loss is often temporary and will resolve by itself or corrected medically or surgically. The treatment for conductive hearing loss will vary depending on the underlying cause.
Impacted earwax: If there is no history of infection, a perforated eardrum or previous surgery to the ear, then warm-water irrigation by a doctor or hearing care professional is a safe method for removing impacted earwax.
Infection of the outer ear: The ear canal is first debrided, ear drops are used in the infected ear. If it is severe infection then a wick is placed in the ear for two to three days to ensure medication is delivered to the affected area. Oral antibiotics may also be prescribed. Your hearing loss should resolve once the inflammation subsides.
Eardrum perforation: If the ear canal is kept dry, then it’s normal for the hole to heal by itself. However, if the ear becomes infected, then oral medication or antibiotic ear drops will be prescribed. If the eardrum still doesn’t heal within two months, then you may require tympanoplasty. This surgery uses different types of grafts to repair the perforation. It’s common for tympanoplasty to be used when there is a chronic infection caused by a perforation.
Infection: Myringotomy is used to release middle ear fluid to allow sound waves to reach your inner ear. During this procedure, a small incision is made through the layers of your eardrum. The fluid is then suctioned from the middle ear through the incision. A sample may be sent to a lab to determine if a virus or bacteria are present. Ventilation tubes are often used to keep the incised eardrum open to help drain the fluid.
If you suspect that you may have conductive hearing loss or have any other concerns about your hearing, then you should schedule a consultation with a hearing care professional as soon as possible. The impact of untreated hearing loss can be devastating and affect all aspects of your health and wellbeing.
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