Hearing loss affects more people than any other sensory disability. Millions of people experience a decline in their hearing abilities due to natural aging or exposure to loud noises. However, certain medical conditions can accelerate this process or cause hearing loss without age or exposure playing a role.
Among the forms of hearing loss affecting our population today is asymmetric hearing loss. In this scenario, the hearing difference between the right and left ear exceeds 15 decibels.
The Three Types of Hearing Loss
The reason so many people are affected by this disability is that no one is immune to hearing loss. Even as a natural process, hearing loss is expected in older generations. In reality, we constantly strain our ears, leading to normal wear and tear over time, age-related decline, and a multitude of factors that can cause hearing loss.
Unprotected exposure to loud noises can lead to hearing loss, as can genetic factors that increase the risk of developing it. Trauma can also damage the auditory organ and cause your hearing abilities to decline. Among those affected, three main types of hearing loss are distinguished: sensorineural, conductive, and mixed.
Conductive Hearing Loss
Conductive hearing loss occurs when one of the three compartments of the ear has an abnormality that physically blocks the conduction of sound waves into the ear. The ear is indeed composed of three compartments, each playing a precise role in the hearing process.
The outer ear consists of two main structures: the auricle and the ear canal. The auricle is the external, easily recognizable part of the ear; it captures sound waves and directs them into the ear canal.
The middle ear is separated from the outer ear by the tympanic membrane, better known as the eardrum. This part of the ear houses the tympanic cavity, where specialized bones that react to the vibrations of the eardrum are located. These vibrations are transmitted to the inner ear by some of the smallest bones in the human body: the ossicles.
This part of the ear houses the cochlea and is the neurological integration center for hearing. Vibrations from the middle ear are converted into electrical signals here, then routed via the auditory nerve to the brain, which transforms them into sounds.
When an element disrupts one of these compartments to the point of blocking sound, it is called conductive hearing loss. The cause can be as harmless as an earwax plug, or as complex as an autoimmune disease that attacks ear cells and causes inflammation and obstruction. It is possible to have both conductive hearing loss due to obstruction and sensorineural hearing loss; this is called mixed hearing loss. Asymmetric hearing loss, however, is generally not related to a transmission problem.
Sensorineural Hearing Loss
Sensorineural hearing loss is characterized by damage to the cochlea or one of the nervous structures involved in hearing. This can be any abnormality, from hereditary hearing loss to damage caused by trauma.
This type of hearing loss often corresponds to the most severe forms. It can also present multiple variations, both in its onset and its manifestations. To diagnose sensorineural hearing loss, you must consult an audiologist and undergo a series of hearing tests that will assess not only the degree of hearing loss but also its type.
Sensorineural hearing loss is the type of hearing loss most likely to manifest asymmetrically.
What is Asymmetric Hearing Loss?
Simply put, asymmetric hearing loss refers to uneven hearing loss between the two ears. When a person experiences hearing loss, it is not uncommon for both ears to be affected in the same way.
In some cases of sudden sensorineural hearing loss, hearing loss can develop gradually, or even unevenly. However, these situations quickly evolve into significant hearing loss, or deafness, equivalent in both ears.
In the case of asymmetric hearing loss, the duration is generally longer, and a specific cause keeps the person in this state of asymmetry. While slight variations from one ear to the other are very common, whether in the quality of hearing or its loss, asymmetric hearing loss is defined by a difference of at least fifteen decibels.
This is a significant difference between two ears. Such a difference never goes unnoticed in a person with asymmetric hearing loss.
But how do you know if you have asymmetric hearing loss, and what causes it?
Diagnosing Asymmetric Hearing Loss
If you think you might have asymmetric hearing loss, the first thing to do is consult your doctor. Most often, if the suspicion is justified, they will refer you to an audiologist. These specialists are dedicated to understanding the ear and identifying the causes of your hearing problems.
The next step is usually to perform an audiogram, which results from a series of tests administered by your audiologist. The results indicate where your decibel thresholds are located.
A decibel threshold corresponds to the precise sound level at which a person perceives a sound. As they propagate, sound waves carry a certain amount of force, or power. This force is measured in decibels.
For example, the hiss of an espresso machine in a coffee shop corner is easily covered by the buzz of a group of friends laughing and talking nearby. These sounds reach your ears with different levels of force. If the hiss were more powerful, it would present at a higher decibel level, and you would notice it despite the laughter and conversations.
An audiogram tells us what our natural hearing thresholds are. As a person loses their ability to hear naturally, their decibel threshold increases. This is why people with hearing loss need specific medical devices like hearing aids: these devices capture certain frequencies that naturally fall below the required decibel threshold and amplify them.
When an audiogram reveals two different thresholds between the ears of the same person, as soon as the difference reaches 15 decibels or more, it is called asymmetric hearing loss.
How Does Asymmetric Hearing Loss Develop?
Just as everyone can experience hearing loss over time or due to loud noises, anyone exposed to intense noise can develop asymmetric hearing loss. If one ear is constantly exposed to loud noise, it will lose hearing faster than the ear that is not directly exposed.
Certain medical conditions can also cause asymmetric hearing loss by disrupting the neurological component of the auditory system. Most asymmetric hearing loss is sensorineural. It can be caused by tumors that develop in the cerebellopontine angle.
Both meningiomas and vestibular schwannomas can develop in this area of the brain. They create pressure that can cause noticeable asymmetric hearing loss. To reach this level of diagnosis, however, an MRI or a brainstem auditory evoked potential (BAEP) test is necessary.
This condition can present in three different ways. In the first case, both ears, although asymmetrically hearing, can be helped by medical treatment. In the second, one ear cannot be helped while the other remains treatable. Finally, asymmetric hearing loss can combine a severely affected ear and a perfectly healthy ear, without any hearing loss. "Rest assured: these tumors are benign and very rare." - Drew Sutton, MD, board-certified otolaryngologist.
Treating Asymmetric Hearing Loss
Since asymmetric hearing loss generally corresponds to moderately severe to profound hearing loss, treatments vary greatly. Surgical implants or bone-anchored hearing aids are one solution to alleviate the more affected ear.
Treatment differs for each individual. The most common form remains hearing aids, available by prescription or over-the-counter depending on your severity and needs. While we always encourage you to seek advice from your primary care physician, we strive to offer the highest quality over-the-counter hearing aids on the market.
Even if a condition like asymmetric hearing loss may require more than an over-the-counter solution, we can still offer an affordable and reliable option to anyone looking to invest in over-the-counter hearing aids. "CLARIA hearing aids can be a pleasant surprise for many patients." - Drew Sutton, MD, board-certified otolaryngologist.
Sources:
Asymmetrical Sensorineural Hearing Loss: Fitting Strategies Donald J. Schum | audiologyonline.com
Bone Anchored Hearing Aids for the Treatment of Asymmetric Hearing Loss| nih.gov
Sudden Sensorineural Hearing Loss (SSHL)| nih.gov
Symptom: Asymmetric Hearing Loss: The Hearing Journal | journals.lww.com
