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How Do We Hear? Hearing Explained

Have you ever wondered how we hear and how the sounds we hear turn into meanings? The auditory centre in your brain is responsible for processing all incoming sound patterns, and filtering out the correct sounds from any background noise. We’ll also discuss the main causes of hearing loss and which part of your hearing range is lost first. 

Hearing & The Brain

Once your ears have received incoming sounds and they’ve been converted into electrical impulses in the cochlea, the real work of hearing begins. Your brain then has to quickly unravel the complex nerve impulses, analyse them, and correctly interpret them.  

Firstly, the auditory centre needs to break down the complex waveforms that arrive as neurological signals into pitch and volume. It then needs to compare the analysed waveforms with your stored patterns. This allows your brain to recognise the origin of a sound and the meaning behind it, for example, it works out whether a sound is speech or a potential danger signal. Background noise like the hum of a restaurant or the wind might be suppressed in your consciousness, while the voice of the person you’re talking to is filtered and amplified, allowing you to understand it better. This permanent and automatic assessment is essential, since you’re unable to focus on all the sounds around you.  

The left hemisphere of the brain has the ability to choose between relevant and irrelevant noises, and although the brain usually decides automatically which sounds you should focus on. It’s also possible for you to influence it, by consciously focusing on a specific sound. So, for example you can listen to an individual voice in a room full of people, or to a single instrument in an orchestra.  

The Main Causes of Hearing Loss

Hearing loss is something that happens gradually as you age, some of the main causes for this include: 

  • Loss of elasticity – As you age, your body produces less elastin. This means that soft tissue across the body becomes less elastic, including parts of your inner ear. This effect means the ears work less effectively and leads to hearing loss. 
  • Damage to the cilia – Your inner ear is covered in tiny, hair-like structures called cilia. These move as sound waves travel through the ear, loud noises can damage these tiny hairs which are unable to recover. Hearing loss can occur over time if enough cilia are damaged. 
  • Chronic health conditions – Health conditions such as diabetes, circulatory problem, and heart disease can have a systemic effect on your body. This can result in widespread deterioration which includes hearing loss.  
  • Medication side effects – some types of medication can cause hearing loss. 

close up of mans ear

Frequency & Volume Loss

Low volume sounds aren’t the only sounds you can struggle to hear with hearing loss, pitches can also be effected as well as the ability to pick sounds out from others.  

A normal ear can pick up sounds starting from a single decibel upwards, as your hearing declines, the volume at which the ear can pick up sounds increases. For example a person with slight hearing loss will be unable to distinguish sounds below 20 decibels, whilst someone with moderate loss will be unable to hear noises quieter than somewhere between 41 to 55 decibels. Once you are unable to hear sounds between 55 and 70 decibels, your quality of life can begin to suffer as human speech averages around 65 decibels and you may struggle to listen or take part in conversations. 

If you are concerned about your ear health or hearing loss, book a free 15 minute hearing health check with one of our experts.