Hearing loss explained

Age-related, gradual hearing loss is common. It is described medically as presbycusis. About one-third of people between the ages of 65 and 75 have some degree of hearing loss. This increases to about 50% of people over the age of 75.

Hearing loss is classified by which compartment of the ear if affects:

Ageing and chronic exposure to loud noises both contribute to hearing loss. Other factors, such as fluid in the middle ear, a hole in the ear drum or even excessive earwax, can temporarily reduce how well your ears conduct sounds. This ‘conductive’ hearing loss can often be reversed.

However, the gradual nerve hearing loss is usually irreversible. Given the complex and varied nature of the hearing loss this should be assessed with your doctor and audiologist to see what should be done to investigate and optimise your hearing.

Symptoms

Hearing loss can manifest in many different ways. Some of these include:

Muffled speech and sound

Difficulty understanding conversation especially when there is competing background noise

Trouble hearing consonants or certain voice frequencies

Frequently asking others to repeat themselves or speak louder

Needing to turn up the volume of the television or put on subtitles

Withdrawing from conversations and social interactions

Avoiding some social settings

WHEN TO SEE A DOCTOR

While gradual, age related sensorineural hearing loss is usually permanent there is another condition that results in sudden hearing loss (called “Sudden sensorineural hearing loss” or SSNHL). It is important if you have a sudden loss of hearing, often just in one ear, that you seek urgent medical review. This can be with your GP who will also involve ENT specialists and audiology to monitor your hearing.

Presbycusis or the gradual hearing loss should also be discussed with your GP. Especially if your hearing is interfering with your daily life. Age-related hearing loss occurs gradually, so you may not notice it at first. Often it is your family members that notice this loss and bring it your attention.

CAUSES OF HEARING LOSS

There are many causes of hearing.More common or those requiring urgent care include the following:

Damage to the cochlea.

Ageing and exposure to loud noise may cause wear and tear on the delicate nerve cells in the cochlea that send sound signals to the brain. These cells are called hair cells. When these hair cells are damaged electrical signals are not transmitted as efficiently, and hearing loss occurs. The cochlear cells do not regenerate. A good analogy is to think of a microscopic piano with 10 000 keys playing a song. As more and more keys are damaged the music becomes more distorted.

The cochlea is arranged according to the pitch. So the higher frequencies are usually affected first in age related hearing loss. This is why higher pitch tones, certain voices or consonants become more muffled.

Ear wax impaction.

Earwax (or cerumen) can block the ear canal and prevent conduction of sound waves. If there is Cerumen removal can be a start to healing assess your hearing. However, it is rarely the only cause of significant hearing loss.

Ear infections, abnormal bone growths or tumours.

Lesions In any compartment of the ear and even rarely in the brain can cause hearing loss. These are rare but it is important to have this assessed medically. Some symptoms such as pain, discharge, blocked sensation, balance concerns or even weak face should prompt urgent medical review.

Ruptured eardrum (tympanic membrane perforation).

Loud blasts of noise, sudden changes in pressure, direct trauma to the eardrum and infection can cause the eardrum to rupture and affect hearing.

RISK FACTORS

Some of the risk factors for hearing loss are unavoidable (we all age!) but there are some habits and exposure that are known to worsen hearing over time or even acutely.

Factors that may damage or lead to loss of cochlear function include:

Loud noise.

Exposure to loud sounds can damage the delicate inner hair cells of the cochlea. Damage can occur with long-term exposure to loud noises or from short blasts. A temporary phenomenon is also seen after attending a loud concert for instance - where there is ‘temporary threshold shift.”

Genetics.

Your genetic makeup may make you more susceptible to ear damage from sound or deterioration from ageing.

Industrial noise exposure.

Occupations where loud noise is a regular part of the working environment such as working in a warehouse, factory or construction can lead to damage inside your ear. It is important to \use hearing protection in these situations.

Recreational noise exposure.

Exposure to explosive noises, such as from firearms and jet engines, can cause immediate, permanent hearing loss. Other recreational activities with high noise levels or listening to loud music can cause hearing loss over time.

Medication.

Certain medications are known to have possible side effects of hearing loss. There are many such drugs and it is important to discuss these side effects with your doctor. Potentially ‘ototoxic’ medications include antibiotic gentamicin and certain chemotherapy drugs such as vincristine. Tinnitus or ringing in the ears can be seen in patients taking very high doses of aspirin or certain diuretics.

Illnesses.

Diseases or illnesses including meningitis can damage the cochlea.

Trauma.

Physical damage to the ear structures can cause hearing loss. Following head trauma, the ear and skull bone (temporal bone) should be imaged to assess for any damage that could cause hearing loss.  

COMPLICATIONS

Hearing loss can have a significant effect on your quality of life. Older adults with hearing loss may report feelings of depression. Because hearing loss can make conversation difficult, some people experience feelings of isolation. Hearing loss is also associated with cognitive impairment and decline.

The mechanism of interaction between hearing loss, cognitive impairment, depression and isolation is being actively studied. Initial research suggests that treating hearing loss can have a positive effect on cognitive performance, especially memory.

Prevention

You can help you prevent noise-induced hearing loss and avoid worsening of age-related hearing loss:

Protect your ears. Limiting the time and intensity of your exposure to noise. In the workplace, you appropriate ear protection. Check with your supervisor.

Monitor your hearing. Annual hearing checks are also indicated especially in high noise workplace environments.

Avoid excessive recreational noise exposure. Activities such as sing power tools or attending loud concerts can damage your hearing over time. Wearing noise-reducing earplugs or taking breaks from the noise can protect your ears. Turning down the music volume on personal earphones is also helpful. Some newer devices have the ability to set the limit of the volume streaming to the earpiece as well.

Conclusion

The ear is a wonderful and complex structure that gives us the sense of hearing. Age-related hearing loss is the most common form of hearing loss later in life. There are some other causes of hearing loss. The risk of noise-induced hearing loss can be minimised with hearing protection.

If hearing loss becomes significant there are strategies to help such has use of hearing aids. The first step, however, is to discuss your hearing loss with your health and hearing care professional.

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