Understanding Hearing Loss
Your ability to hear is important as it may affect your quality of life. Hearing enables you to communicate with friends, family and colleagues, gives you access to information and entertainment, and can warn you in the event of danger (i.e. A car driving in your direction).
How Does Hearing Work
A healthy auditory system is able to recognise frequencies between 20 – 20 000 Hz. In simple terms, a low pitch sound such as a bass drum would be between 20 – 100 Hz and a high pitch sound such as a mouse squeak would be up to 20 000 Hz. In fact, a mouse squeak can also reach above 20 000 Hz which is in the range above what a human can hear.
Speech sounds, however, range from roughly 300 – 3400 Hz. Your brain is good at understanding language and can cope well with sound in many situations. In a shopping mall, for example, our brain is able to filter out unnecessary information and focus on the voice of the person you are talking to. Because you have 2 ears, you are also able to hear sounds from all around you and determine where these sounds are coming from, known as localisation.
Your ear is made of up 3 sections, each with their own role in perceiving sound.
The outer ear consists of the pinna, which is the part that sticks out from the skull. We generally refer to it as “the ear” as it is the part that we can see. It is made up of skin and cartilage and collects and focuses sounds into the ear canal and the rest of the auditory system.
The outer ear includes the ear canal, which is about 4 cm long and has hairy skin containing sweat glands and oil glands which together form earwax. Wax is naturally created by your ear canal, and it acts as a barrier to foreign objects and as a natural disinfectant.
The outer ear is the first part of the auditory system and directs sounds to the eardrum which separates the outer and middle ear. The eardrum converts sound waves to which are passed on to the middle ear.
The middle ear houses three tiny bones known as the malleus, incus and stapes. These are the smallest bones in your body. Their job is to conduct sound from the eardrum to the inner ear. The malleus is embedded onto the eardrum and connected to the incus. The stapes is attached to the incus and its ‘footplate’ covers the oval window – an opening into the inner ear or cochlea.
Vibrations of the stapes vibrate the fluid (perilymph) within the cochlea. Sending the signal into the inner ear.
The inner ear consists of the cochlea. The cochlea is shaped like a snail shell with two and a half turns. The shell of the cochlea is made of bone and houses the organ of hearing, known as the membranous labyrinth which is surrounded by a fluid called the perilymph.
Within the cochlea (Latin for snail shell), there are up to 30,000 hair cells which convert sound vibrations into nerve impulses and about 19,000 nerve fibres which transmit electrical signals to the brain via the cochlear nerve to process.
What is hearing loss
Hearing loss is the reduction or total loss of the ability to hear which can make it difficult for one to hear and understand speech and other sounds. Hearing loss does not necessarily mean that your total hearing is softer, it also means that certain sounds and syllables are harder to hear.
For example, high-pitched letters such as “T” and “S” are easily masked or hidden by louder low-pitched sounds such as “B” and “U”. So, while you may physically be able to hear, you will struggle with particular sounds and struggle to understand what people are saying even when you can hear them talk.
Approximately 32 million children live with disabling hearing loss globally.
Approximately 15% of the world’s adult population has some degree of hearing loss. With 25% of them being over 65 years of age.
Imagine having dinner in a busy restaurant with your family. With dishes clattering, classical music playing in the background and guests at the next table constantly bursting into laughter. You are straining to hear the words and follow the conversation at the table. Trying to make sense of the conversation by ‘filling in the gaps’ is making you tired.
You learn to play along. You smile and nod even though you don’t know what the question or statement was, hoping your response is right. It is really exhausting and you just want to go home. Now, imagine struggling to hear your children, friends and family members talking to you, even in the quiet of your home? You begin to feel disappointed, angry, and stop making an effort to communicate until eventually, you give up.
Imagine the impact on your family, work and social life
Types of hearing loss
There are different types of hearing loss, each with differing treatment and results.
Loss of hearing is caused by physical damage to your hearing system through injury, some medications or, most commonly, overexposure to noise and falls into one of three categories.
Conductive hearing loss (CHL)
Conductive hearing loss, indicated in purple on the above diagram, is caused by issues in the outer and the middle ear. A conductive hearing loss means that sound cannot be transmitted into the inner ear. Some common causes of CHL are ear infections and excessive wax build-up. With correct management, a conductive hearing loss can be easily treated. Either through medication for infections or through the removal of excessive wax buildup.
Sensorineural Hearing Loss (SNHL)
Sensorineural hearing loss, indicated in pink on the diagram, is a result of damage to the inner ear hair cells or the nerve that transmits signals from the ear to the brain. This type of hearing loss is generally associated with the natural ageing process. The older you get, the more the hair cells in the cochlea get damaged. Another cause of this type of hearing loss is exposure to excessive noise and some medication (known as ototoxicity) which can destroy or damage the hair cells inside the cochlea. Those with SNHL may be fitted with hearing aids. Hearing aids improve your hearing functionality by amplifying certain sounds as they reach the ear. Assistive listening devices such as FM systems and auditory rehabilitation may also be prescribed as treatment for SNHL.
Mixed Hearing Loss
A mixed hearing loss is a mixture of both CHL and SNHL. This could be the combination of age-related hearing loss and an ear infection because of a cold or a number of similar combinations.
Symptoms Of Hearing Loss
If you answer yes to any of the questions below, visit your hearing healthcare professional.
Do you find that you often have to ask people to repeat themselves when speaking?
Do you find that people mumble when they talk?
Do you think that everyday sounds such as birds chirping are much softer or gone completely?
Do you often have to increase your TV, radio or phone volume?
Do people complain that they have to repeat themselves a lot?
Do you often have to look at people’s faces (lip read) for clarity when they are talking?
Early Detection and Prevention Are Key To Hearing Conservation
If you suspect that your hearing ability may be deteriorating, visit your Audiologist or your General Practitioner and request a hearing test.
They will test your hearing with an audiometer which is a device specifically designed to measure how well you hear. The problem may be stopped from further development or, in the case of ear infections, easily treated with antibiotics.
The number one cause of hearing loss is exposure to excessive noise.
Take care of your hearing but avoiding areas where noise is an issue, wear hearing protection where appropriate and avoid listening to music at extreme volumes and remember to allow your ears to rest and recover after exposure to noise.