Conductive hearing loss is a type of hearing loss that occurs when sound is prevented from reaching the inner ear. This blockage of sound occurs in either the outer ear or the middle ear. In this case, the inner ear is perfectly normal, but since sound does not reach it, it cannot send any signals to the brain. Without impulses transmitted to the brain, the brain receives no information about sounds, which results in hearing loss. If you suffer from conductive hearing loss, the sound level entering the ear is reduced on its way to the cochlea in the inner ear. This results in difficulty hearing soft sounds, while loud sounds seem muffled.
Signs of conductive hearing loss
Since the auditory nerve and inner ear of a person with conductive hearing loss are intact, the main difficulty encountered concerns sound volume rather than clarity. This is the reason why you have to turn up the volume on the television or ask those around you to speak louder to understand what is being said. Like any other hearing loss, conductive hearing loss is often accompanied by several symptoms. Here are a few:
Sounds that are muffled or blocked in one ear.
A sensation of fullness in the ear. Your ears may also feel clogged.
Unexpected hearing loss in one or both ears.
Pain in the ear or head.
Difficulty understanding words, especially in a crowd or in the presence of background noise.
Avoidance of social gatherings and withdrawal from conversations.
Asking your interlocutors to speak more slowly, louder, more distinctly, or to repeat themselves.
Frustration during telephone conversations.
Easier hearing in one ear than the other.
Difficulty hearing soft sounds, both in the low and high frequencies.
Difficulty hearing consonants.
Fluid draining from the ear. This fluid may be clear or yellow, and sometimes accompanied by a bad odor.
The impression that your own voice is louder or different.
Causes of conductive hearing loss
Conductive hearing loss can have many origins. For clarity, its causes will be grouped into two categories, depending on the part of the ear involved: the outer ear and the middle ear.
The outer ear
Causes of conductive hearing loss located in the outer ear include:
1. Stenosis
This is the narrowing of the ear canal. Stenosis occurs when dense, thick fibrous tissue forms in parts of the outer ear canal. The formation of this thick tissue causes conductive hearing loss. Stenosis can be caused by chronic or long-term otitis externa, chemical burns, gunshot wounds, and the accumulation of thick, dry skin in the ear canal. Most cases of stenosis are temporary and can be treated with ear drops.
2. Earwax accumulation
Earwax is a waxy substance produced by the glands of the ear canal; it traps water, dust, and other particles and prevents them from reaching the eardrum. Without earwax, these particles or substances would reach the eardrum and could damage or infect it. It is normal for the body to produce earwax, but when this production becomes excessive, hearing can suffer. Normally, when the body produces the right amount of earwax, it dries and exits the ear naturally; however, in the case of excessive accumulation, the earwax can harden and be pushed deeper into the ear canal. This prevents sound from passing through the ear canal to the inner ear and causes conductive hearing loss. People with narrow or atypically shaped ear canals often suffer from hearing loss related to an earwax plug.
Conductive hearing loss due to earwax accumulation is often temporary. Once the earwax is removed, normal hearing is restored.
3. Otitis externa
Otitis externa, also known as "swimmer's ear," is an infection of the outer ear canal. This infection is caused by water stagnating in the ear after swimming. It often extends from the eardrum to the outside of the head. Water stagnating in the ear creates an environment conducive to the development of bacteria and fungi. Their proliferation in the ear leads to inflammation of the outer ear canal. In addition to this inflammation, otitis externa is also characterized by itching of the ear canal, ear pain, temporary hearing loss, and pus or discharge from the affected ear.
4. Exostoses
Exostoses are also called bony spurs. This is the formation of new bone or a bony outgrowth on the surface of a bone. Exostoses can appear anywhere, including inside the ear. They are also commonly referred to as "surfer's ear." They are often associated with surfers because this abnormal bone formation in the ear canal is due to exposure to cold wind and water. Exposing the ear to cold wind causes the bone surrounding the ear canal to develop small bony outgrowths. This growth can narrow or obstruct the ear canal. This obstruction can trap water and earwax in the ear and cause an infection. When bony spurs form in the ear canal, they create blockages and limit the passage of sound from the outer ear to the inner ear. Exostoses do not only affect surfers: they also affect people who practice activities in cold weather, such as diving, kayaking, jet-skiing, windsurfing, and sailing.
5. Microtia
This is a congenital anomaly present in children. Although the exact cause of microtia remains unknown, it has been linked to the consumption of drugs or alcohol, a low-carbohydrate diet, the use of the anti-acne drug Accutane, and certain genetic conditions during pregnancy. This birth defect makes the outer part of the child's ear underdeveloped or deformed.
Microtia often develops during the first trimester of pregnancy and most often affects only one ear. In rare cases, it affects both ears.
The middle ear
Common causes of conductive hearing loss located in the middle ear include:
1. Perforation of the eardrum
A breach or rupture of the eardrum, also called the tympanic membrane, can cause conductive hearing loss. A perforated eardrum can result from inserting sharp objects into the ear, chronic ear infections, a sudden change in pressure, sudden exposure to intense noise, or trauma or a blow to the head. A perforated eardrum is common, and in most cases, the eardrum heals on its own within a few days. In rare cases where the damage is severe, a tympanoplasty can be performed to repair the damage. Symptoms of a perforated eardrum include: pain radiating into the face, hearing loss, ringing in the ear, dizziness, infection, and water draining from the ear after swimming. Throughout the period that the eardrum is perforated, hearing loss occurs because sound entering the middle ear from the outer ear can no longer be relayed to the inner ear.
2. Tympanosclerosis
This is a condition that causes thickening or calcification of the tympanic membrane. Tympanosclerosis has no obvious symptoms other than conductive hearing loss. Without a proper medical examination, it is difficult to diagnose. The ear must be examined for it to be identified. The easiest way to spot it: upon inspection of the ear, whitish, chalky-looking plaques appear on the eardrum.
3. Otitis media
Otitis media refers to a group of inflammatory diseases of the middle ear. It is often triggered by fluid buildup in the middle ear. A common type of otitis media is acute otitis media. In addition to ear inflammation, acute otitis media is also accompanied by ear pain. Otitis media can cause conductive hearing loss in both adults and children. Another type is seromucous otitis, or otitis media with effusion: this is the presence of non-infectious fluid in the ear for more than three months. It does not cause an infection but can cause an occasional sensation of fullness in the ear.
4. Eustachian tube obstruction
The Eustachian tube is a small canal located between the middle ear and the upper part of the throat, responsible for balancing pressure in the ear and draining fluid from the middle ear. Eustachian tubes are naturally designed to remain closed, but they open when you yawn, chew, or swallow. The Eustachian tube can become blocked for various reasons. Its obstruction leads to tubal dysfunction, characterized by pain, a sensation of fullness in the ear, tickling in the ear, tinnitus, hearing difficulties, and ear pain. Eustachian tube obstruction is often temporary and can be resolved with simple home remedies. However, it remains important to see a doctor in case of recurring episodes.
5. Otosclerosis
Otosclerosis is the medical term used to describe the hardening or abnormal remodeling of the bones of the middle ear. Bone remodeling is a natural process of the body intended to replace old tissue with new tissue. Bone remodeling that does not follow its natural course can hinder the propagation of sound from the middle ear to the inner ear and cause conductive hearing loss.
6. Rupture of the ossicular chain
This is a rupture or interruption of the connection between the bones of the middle ear. The middle ear has three bones: the incus, the stapes, and the malleus. These three bones are collectively called the ossicles. Sound vibrations picked up by the outer ear are routed from the eardrum through the ossicles. The stapes then transmits these vibrations to the fluids of the inner ear. If the ossicles are not correctly connected or if they are detached, the middle ear will not be able to relay sound to the inner ear, which causes conductive hearing loss.
Rupture of the ossicular chain can be caused by otosclerosis, infection, a skull fracture, or trauma.
Difference between mild and moderate conductive hearing loss
Like any other type of hearing loss, conductive hearing loss comes in several categories depending on the degree or severity of the impairment. In this article, we will focus on mild and moderate conductive hearing loss. Hearing loss is classified into categories based on the minimum threshold that a person is able to perceive. This minimum threshold is measured in decibels (dB). The decibel is the unit used to express the intensity of sounds. Before examining the difference between mild conductive hearing loss and moderate conductive hearing loss, it is important to remember that not all hearing loss is the same. Even if two people have the same type or degree of hearing loss, their experience and the impact on their daily life will never be identical. It should also be noted that the fact that hearing loss is described as mild or moderate does not mean that the hearing and communication difficulties are the same. To examine the differences between these two levels, we will study each type of hearing loss separately, detailing its characteristics.
Mild conductive hearing loss
The thresholds for mild hearing loss are between 25 and 40 decibels. Mild hearing loss can be well managed by adults, but in children, it can delay language development. The sensation caused by mild conductive hearing loss can be compared to placing your fingers in your ears. It is often due to a problem in the outer ear that prevents proper reception and transmission of sound to the middle ear and the inner ear.
Here are some symptoms of mild conductive hearing loss
Difficulty hearing soft voices, those of people who speak quietly, or young children.
Difficulty hearing speech or following conversations in noisy places.
Ease in hearing vowels, which are loud and intense sounds, but difficulty perceiving softer consonants.
Repeating or asking to repeat during conversations.
Moderate conductive hearing loss
People with moderate conductive hearing loss have thresholds between 41 and 55 decibels. It is often characterized by difficulty hearing speech at a normal volume level. In most cases, hearing aids are prescribed for people with moderate hearing loss. Vocabulary, language, and comprehension of children with moderate conductive hearing loss are often affected. Here are the symptoms of moderate conductive hearing loss:
Difficulty understanding speech without hearing aids. You may be able to hear without hearing aids, but you will have trouble understanding what is said.
Speech must be very loud to be understood.
Turning the volume of the television, radio, and telephone to high levels.
Difficulty following conversations.
Difficulty hearing vowels and missing out on consonants.
Reading the few symptoms of each type of conductive hearing loss mentioned above, it is clear that there are differences between the two. For example, a person suffering from mild conductive hearing loss may hear vowels but experience difficulty with soft consonants. People with moderate conductive hearing loss, however, do not just have trouble hearing vowels: they also miss the consonants. Furthermore, in most cases of mild conductive hearing loss, the difficulty seems related to soft sounds, whereas with moderate conductive hearing loss, the problem concerns not only hearing: comprehension is also affected. Without hearing aids, a person with moderate hearing loss can hear speech but fails to understand what is being said. This indicates that the underlying cause goes beyond the outer ear to reach the middle ear. In other words, the outer ear receives the sound well, but the middle ear fails to transmit it to the inner ear, from where the sound signal should go to the brain to be interpreted. Thus, even if sound enters the ear, what is being said remains incomprehensible. With mild conductive hearing loss, on the other hand, the sound may seem muffled, but comprehension is not affected. Most people with mild conductive hearing loss learn to manage it and lead a normal life without consequences, while those suffering from moderate conductive hearing loss generally need hearing aids to function properly.
Conclusion
Whether mild or moderate, conductive hearing loss can be temporary or permanent. Some of the causes mentioned above are progressive. It is therefore important to consult quickly as soon as you notice a problem with your ears. Early medical care can prevent permanent damage. However, when hearing loss is permanent, certain devices can help your hearing.
Do you suffer from mild or moderate conductive hearing loss? What symptoms do you experience? Share your experience with us.
