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Conductive Vs Sensorineural Hearing Loss

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Hearing loss affects millions of people worldwide. As a condition, hearing loss is typically the result of aging, disease, and heredity.

Hearing loss can affect anyone, regardless of age. Some are born with varying degrees of hearing loss, while others develop it from various environmental factors over time.

Generally, hearing loss is broken down into two main categories: Sensorineural and conductive hearing loss. The type determines what treatments will work.

Let’s take a deeper look at these two types of hearing loss and what makes them different.

A Quick Look at Hearing Loss

According to data put out by the World Health Organization, over five percent of the world’s population require some sort of rehabilitation to address hearing loss — that’s around 430 million people. These numbers are projected to double by 2050.

In the United States, roughly 15% of adults, or 37.5 million, report some level of hearing loss or hearing troubles. Among adults aged 20 to 69, aging is the strongest predictor of hearing loss.

But hearing loss can affect anyone or any age.

According to the hearing loss statistics by the CDC, about two to three out of every 1,000 children in the United States are born with some detectable level of hearing loss in one or both ears.

So, hearing loss is much more prevalent than some might imagine. It is important to note that hearing loss is not always synonymous with deafness.

Degrees of Hearing Loss

There are degrees of hearing loss, ranging from normal to profound. These levels are confirmed through a hearing test with an audiologist. It is based on how loud sounds need to be for you to hear them and measured using a range of decibels (dB).

  • The normal degree of hearing loss (-10 to 15 dB)
  • A slight degree of hearing loss (16 to 25 dB)
  • A mild degree of hearing loss (26 to 40 dB)
  • A moderate degree of hearing loss (41 to 55 dB)
  • Moderately severe degree of hearing loss (56 to 70 dB)
  • Severe degree of hearing loss (71 to 90 dB)
  • Profound degree of hearing loss (91+ dB)

The ear is made up of three parts: The outer, middle, and inner ear. In short, the outer part of the ear helps collect and gather sounds. The middle ear turns sound waves into vibrations and sends them to the inner ear.

These are changed to nerve signals via the auditory nerve, which gets sent to the brain.

Conductive and Sensorineural Hearing Loss

There is no one-size-fits-all approach to hearing loss. Treatment (if possible at all) depends on how the hearing was lost.

For example, treatment for hearing loss due to trauma will look much different from hearing loss due to disease.

Typically, hearing loss can be put into two categories: Conductive and sensorineural.

The former results from trauma or obstruction, while the latter involves the inner ear and auditory nerves. Let’s take a closer look at each.

Conductive Hearing Loss

Out of the two hearing loss categories, conductive hearing loss would be considered the least common type. Typically, conductive hearing loss occurs when there is an obstruction or trauma to the outer and middle ear. This is what prevents sound from reaching the inner ear. This type of hearing loss could be temporary or permanent.

The causes for conductive hearing loss can vary greatly and are generally determined by which part of the ear is affected, whether the outer or middle ear.

Here are some of the most common causes:

  • Wax impaction – Earwax, or cerumen, gets stuck or impacted in the ear canal, muffling and obstructing sound.
  • Obstruction by a foreign body -- When small items are stuck in the ear canal, obstructing sound. This is typical in small children.
  • Infections -- like swimmer’s ear (otitis externa) in the ear canal can also cause temporary conductive hearing loss, as can fluid buildup from infection in the middle ear.
  • Growths or tumors – In some cases, tumors or benign growths can block the outer and middle ears, leading to conductive hearing loss.
  • Trauma – Any trauma that fractures the ossicles bones in the middle ear can also disrupt the normal hearing.

Treatments for conductive hearing loss vary depending on the cause.

For example, earwax can be extracted, and there are medications to help combat infection, but abnormalities or trauma to the ear could result in surgery.

Sensorineural Hearing Loss

Sensorineural hearing loss is considered the most common type of hearing loss. Normal aging is the most common cause of sensorineural hearing loss. Medically, this is known as presbycusis or age-related hearing loss.

In fact, some degree of age-related hearing loss affects approximately one-third of adults between the ages of 65 to 70.

Constant exposure to loud noise can also do damage to the inner ear over time. This is typical in outdoor jobs, such as construction. Also, constant exposure to loud music via earbuds can have a similar effect.

Here are some less common causes for sensorineural hearing loss:

  • Medication side effects (ototoxic medications)
  • Illness and disease, such as mumps, diabetes, and Meniere’s disease

Generally, this type of hearing loss is permanent since the damage is done to the hair-like cells known as stereocilia within the inner ear or the auditory nerve that delivers sound to the brain. However, hearing aids and cochlear implants are well-known treatments.

Conclusion

Hearing loss affects hundreds of millions of people around the world. Typically, the major cause of hearing loss is due to aging.

There are degrees of hearing loss that range from normal to profound. Hearing loss can be progressive over time or present suddenly without warning.

Conductive and sensorineural are the two most common types of hearing loss, with the latter being the most common. While they do share similarities, their causes and treatments can vary greatly.

Sources:

Deafness and hearing loss | WHO

Quick Statistics About Hearing | NIH

Degree of Hearing Loss | ASHA

Causes of Conductive Hearing Loss | ASHA

About Sensorineural Hearing Loss | ASHA

Age-related hearing loss (presbycusis) - Why do people lose hearing in old age? | Healthy Hearing

Healthy Directions Staff Editor