What causes hearing loss?
As we get older, changes in the inner ear and hearing pathways can affect how well we hear. Age-related hearing loss – called presbycusis or presbyacusis – develops differently from person to person and is influenced by a combination of ageing, genetics, health and lifetime exposure to noise.
Age-related hearing loss usually develops gradually and becomes more common as we get older. Around one in five people aged 65–74 experience hearing difficulties, rising to more than one in three among those aged over 74. Because the changes can be gradual, regular hearing checks become increasingly important with age.
Signs of hearing loss
Age-related hearing loss often develops slowly, so changes in hearing may not be immediately noticeable.
High-frequency sounds can become more difficult to hear first, such as birdsong, bells or some higher-pitched voices.
You may notice that everyday sounds such as birds singing, a doorbell or an alarm are harder to hear. You may also find yourself increasing the television volume, having difficulty following telephone conversations or asking people to repeat themselves more often. These can all be signs that your hearing has changed.
Difficulty following conversations in places with background noise – such as restaurants, social gatherings or meetings – is another common sign. If you notice changes like these, a hearing check with a qualified hearing care professional can help you better understand your hearing needs.
Noise
We encounter sound throughout everyday life – at work, in traffic, through personal audio devices and at concerts or other events. Repeated or prolonged exposure to loud sound can damage the sensitive structures of the inner ear and lead to permanent noise-induced hearing loss.
How loud is “too loud”?
The risk to hearing depends on both how loud a sound is and how long you are exposed to it. According to the WHO, sound at 80 dB can be listened to safely for up to around 40 hours per week, while at 90 dB this falls to around four hours. Louder environments, including some concerts, workplaces and personal audio devices at high volume, can reduce safe listening time even further. Reducing the volume, taking listening breaks and using appropriate hearing protection can all help protect your hearing.
Diseases
Hearing loss can also be associated with certain ear conditions, infections and chronic health conditions. Some common examples include:
- Middle ear inflammation (otitis media): Middle ear infections are particularly common in children and are often temporary. However, recurring or persistent infections and fluid in the middle ear can affect hearing and should be assessed by an appropriate healthcare professional.
- Otosclerosis: Otosclerosis involves abnormal bone remodelling in the middle ear, which can restrict movement of the stapes – one of the small bones involved in transmitting sound. Depending on individual circumstances, hearing aids or surgery may be considered to improve hearing.
- Diabetes: Hearing loss is more common among people with diabetes. Research suggests that changes in blood glucose over time may affect the small blood vessels and nerves involved in hearing, although the relationship between diabetes and hearing health continues to be studied.
Types of hearing loss
Sensorineural hearing loss (SNHL)
Sensorineural hearing loss results from damage or changes to the sensory cells or nerve pathways of the inner ear. It is the most common type of hearing loss and can be associated with ageing, exposure to excessive noise, genetic factors and certain health conditions.
Sensorineural hearing loss can develop gradually or occur more suddenly. It may affect one or both ears, and the degree of hearing loss can differ between them. Where there is a significant difference in hearing between the two ears, it may be described as asymmetric hearing loss.
Conductive hearing loss
Conductive hearing loss occurs when sound cannot travel effectively through the outer or middle ear to the inner ear. Unlike sensorineural hearing loss, the sensory cells of the inner ear may continue to function normally.
Common causes include a build-up of earwax, middle ear infections, fluid behind the eardrum, a perforated eardrum or changes to the structures of the outer or middle ear. Depending on the cause, conductive hearing loss may be temporary or may be addressed through medical, surgical or hearing-care interventions.
Unilateral or bilateral hearing loss
Hearing loss can affect one ear, known as unilateral hearing loss, or both ears, known as bilateral hearing loss. People with hearing loss in one ear can find it more difficult to identify where sounds are coming from or follow conversations when there is background noise.
Sudden hearing loss
Sudden sensorineural hearing loss is a rapid change in hearing that usually develops in one ear over a period of hours or a few days. It may be accompanied by tinnitus, a feeling of fullness in the ear or dizziness.
A sudden change in hearing can have different causes. Some, such as earwax or middle-ear problems, affect the transmission of sound, while others involve the inner ear or auditory nerve. Determining the cause requires prompt medical assessment.
