Unilateral Hearing Loss: Why Can Hearing Loss Affect Each Ear Differently?
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Unilateral Hearing Loss: Why Can Hearing Loss Affect Each Ear Differently?

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Hearing loss generally affects both ears to the same degree, which is what your audiologist refers to as bilateral hearing loss. However, it is possible for adults and children to have hearing loss in one ear only. This is called unilateral hearing loss or single-sided deafness. 

You can have unilateral hearing loss with the other ear completely normal or an asymmetric hearing loss where there is a hearing loss in both ears, but one is significantly worse than the other. 

Hearing loss is usually gradual and a result of age, noise exposure, environmental causes or genetics but hearing loss can also happen suddenly. 

A large, sudden hearing loss in one ear should raise red flags and requires prompt treatment. 

How Does Your Hearing Work?

The ear is split into 3 parts: The outer, middle and inner ear. The outer ear is made up of the pinna, ear canal and eardrum. Behind the eardrum is the middle ear where there are three tiny bones that vibrate and transduce sound to the inner ear or hearing organ. 

When we hear a sound, the sound waves travel through the ear canal, causing movement of the eardrum which sets the bones in the middle ear into motion. They vibrate and transmit these sound waves to the inner ear which stimulates a specific area of the hearing organ. 

Nerves connected to this specific area then send the message to the brain where sounds are interpreted and made sense of. 

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Types of Hearing Loss: Sensorineural vs Conductive Hearing Loss  

Unilateral Hearing Loss is a specific form of hearing loss that occurs only in one ear, with normal hearing in the other. 

Depending on which part of the ear has been damaged will determine the type of unilateral hearing loss. 

A conductive hearing loss comes from damage to the external or middle ear and can be temporary or permanent. A conductive loss is commonly caused by an ear infection, perforation of the eardrum or issues with the ear canals or bones in the middle ear. 

Sensorineural hearing loss is a consequence of damage to the inner ear, this type of hearing loss is usually permanent in nature as our bodies cannot repair or regenerate the cells in the hearing organ. The most common cause of sensorineural hearing loss is ageing and noise exposure. 

Causes of Unilateral Hearing Loss

  • Ear Infections

Ear infections can be bacterial, fungal, or viral. They can be caused by water trapped in the ears from swimming, from having a cold or sinus infection. Infections can affect one or both ears and cause a temporary hearing loss when the infection is active as sound is unable to travel through the ear as usual. 

Common symptoms of an ear infection are a dull ache or sharp stabbing pain, smelly discharge, and blocked feeling in the ears. It is very important to visit your GP if you have any of these symptoms to treat the infection straight away. 

An infection left untreated or recurrent infections can start to erode the bone of the ear canal and eardrum causing irreversible damage and a permanent conductive hearing loss.

  • Genetics

Babies are born with a hearing loss or with a genetic disease that may cause a progressive deterioration in the hearing as they get older. Congenital hearing loss tends to be of a sensorineural nature. Babies can be born with unilateral hearing loss from diseases such as measles, mumps and meningitis and other pregnancy and birth complications. 

Syndromes such as Waardenburg’s Syndrome and Branchio-oto-renal Syndrome usually cause progressive bilateral hearing loss. Growth deformities of the pinna or ear canal can also cause conductive hearing loss in one or both ears. 

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  • Age

Over time, just like the rest of the body, the cells in the hearing organ will undergo wear and tear and eventually perish. Unfortunately, there is no way for the body to regenerate these cells, that’s why your hearing is very precious, once it’s gone it will not come back. 

This deterioration in hearing is expected and becomes most noticeable for people aged over 60. It is a gradual sensorineural deterioration that usually affects both ears equally, but sometimes one ear can be worse than the other.

  • Noise Exposure

Prolonged exposure to loud sounds will damage the hearing organ and cause sensorineural hearing loss. This damage is gradual and not noticeable straight away so it’s important to wear hearing protection. 

It is typical for noise-induced hearing loss to affect both ears equally but it is possible for one ear to be affected more than the other. People who work in the same position with noise predominantly on one side, for example, or those who use power tools or artillery with their dominant hand may see a larger hearing loss on the same side ear.  

  • Head Trauma

Head injuries direct to the ear or to the head can damage any part of the ear. Depending on the site of injury, this can cause a hearing loss to one ear or both. Be careful to wear proper headgear and protection when working on construction sites and always wear a helmet when riding a bike or motorcycle and when participating in extreme sports. 

  • Acoustic Neuroma

This is a type of tumour that grows on the hearing nerve. The most common symptoms of acoustic neuroma are unilateral hearing loss, tinnitus (sounds in the ear), blocked or pressure feeling in the ears, vertigo (spinning sensation) and facial numbness. 

If you feel a sudden drop in the hearing with these accompanying symptoms, visit your local audiology clinic as soon as possible and let your GP know about it so he can refer you for a specialist opinion. 

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Sudden Sensorineural Hearing Loss

Hearing loss can happen overnight with no warning. Sudden sensorineural hearing loss usually affects one ear only, it is less likely for both ears to be affected. If you feel your hearing has dropped significantly and suddenly, do not wait. 

Go to see an audiologist immediately to have your hearing tested. Sudden sensorineural hearing loss is treated with steroids which are most effective within 72 hours from when the hearing loss first occurs. 

It is imperative to act efficiently and quickly to have your hearing tested then be referred on for treatment. Acting quickly will ensure the largest possibility of recovering hearing.  

What Are the Symptoms to Watch Out For?

People with unilateral hearing loss may experience the following symptoms:

  • Problems localising the source of a sound
  • Preference to listen to conversations or music on their non-impaired side
  • Problems with understanding conversations in noisy surroundings
  • Inability to filter out background conversations and noises
  • In children, unilateral hearing loss may cause difficulties in school performance

The Next Steps

Whilst bilateral hearing loss is most common, there are many situations and circumstances that can cause unilateral hearing loss. It is essential to see an audiologist to have your hearing assessed to determine the degree and type of hearing loss. 

Prevention is always better than cure so be proactive in protecting your hearing! Wearing earplugs when swimming, hearing protection when working in noisy environments and being aware of your hearing health and having regular check-ups will ensure your hearing is looked after. 

To book a free 15-minute hearing test at an Attune Hearing audiology clinic near you, visit our website or give us a call at 1300 736 702.

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