Types and Causes of Hearing Loss
Hearing is a vital sense that we use daily. We use it in our social and professional lives, we use it to unwind and relax, and it is integral to how we communicate with those around us. So, we need to keep an eye on it and not take it for granted.
Hearing loss can lead to feelings of isolation and depression, yet, on average, people wait seven years after initial symptoms before seeking the help that they deserve from a hearing practitioner.
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Oftentimes, people think that their level of hearing loss is ‘not bad enough’ to seek help or they talk themselves out of it because ‘it is just a part of getting older’. Others may fear the necessity of a medical procedure, however only 5% of hearing loss cases can be improved medically or surgically. For the remaining 95%, hearing aids can vastly improve the lives of those living with even mild hearing loss, so there is no reason to struggle in a world with muted or less distinct sounds.
Signs of hearing loss
Here are a few things to take into account if you’re suspecting you, or someone around you, may have hearing issues.
- You ask people to repeat themselves often.
- Group conversations are difficult to follow.
- People tell you that the TV or radio is too loud.
- Sometimes you miss the doorbell or phone ringing.
- Certain sounds, especially speech, are hard to make out in noisy environments.
How do we hear?
Our ears are made up of three parts, the outer ear, middle ear and inner ear.
The outer ear – also called the pinna or auricle, acts as a funnel, collecting sounds to channel them into the ear canal or external auditory canal. The ear canal’s role is to form earwax containing chemicals that fight off infections. These infections could damage the inside of the ear canal. Earwax also helps to keep the ear canal clean and free of dust and dirt.
At the end of the ear canal is the eardrum – this is where the middle ear starts. The eardrum is a thin piece of tightly stretched skin, made to vibrate when sound waves hit it.
When this happens it moves a set of three tiny bones on the inside. These three bones are called the ossicles and are made up of the hammer (or malleus) incus and stapes. These bones are connected to the cochlea which is a small curled tube filled with fluid and lined with tiny hair cells. The vibrations sent through the ossicles create waves in the fluid which move the hair cells. These cells then translate vibrations into electrical impulses which are carried to the brain by sensory nerves. The nerves send unique signals for each sound, as high-frequency and low-frequency sounds affect the hair cells in different ways. This is how sounds are distinguished from one another.
Diagram like this or:
Types of hearing loss
Hearing loss can be categorised into three basic types depending on which part of the auditory system is affected. Speaking to an audiologist can be useful in testing and diagnosing your hearing loss to provide a better idea of the category you may fall into.
- Sensorineural hearing loss
Sensorineural hearing loss is the most common type of hearing loss, and in certain cases, it isn’t actually the auditory nerve causing a problem, but the tiny hair cells that line the cochlea.
When these hair cells are damaged, they cannot move and flex as well as they used to, resulting in signals failing to travel to the brain correctly. These signals contain information about the loudness and clarity of sounds, so if they are weakened, hearing loss is experienced.
The two biggest causes of sensorineural hearing loss are excessive exposure to loud noise and age.
If hair cells receive a lot of damage from noise (either impact sounds or long duration sounds), then hearing loss could be sustained. The good news is that this is preventable with hearing protection.
If age is the cause of the damage, then hearing aids will help as long as the inner hair cells are not damaged too severely. There are three rows of hairs in the cochlea and an audiologist can assess the severity of the damage.
This type of hearing loss is typically treated with air conduction hearing aids which amplify sound. These work by:
- The microphone receives the sound and converts it into an electric signal.
- The amplifier, which is located between the microphone and loudspeaker, strengthens or boosts the electric signal which increases the amplitude of the sounds supplied by the microphone.
- The loudspeaker then converts the electric signal back into sound which flows through the tube, ear mould and into the person’s ear.
Amplification only helps hearing loss if the inner ear, also known as the ‘organ of hearing’, or the cochlea, is damaged (but not too severely). All the other pathways have to be clear and working well in order for the sounds to be cleanly transmitted all the way to the inner ear.
Some causes of sensorineural hearing loss include:
- Deterioration caused by age (presbycusis)
- Excessive exposure to loud noise
- Viral or bacterial infections
- Autoimmune diseases
- Traumatic injuries
- Meniere’s disease
- Growths in the inner ear
- Medication side effects
- Hereditary factors
- Conductive hearing loss
Conductive hearing loss relates to any issue within the region between your stapes (one of the bones in your inner-ear) to the external ear. It is caused by some kind of physical interference that prevents the proper transmission of sound waves from the inner ear into the cochlea. This could be an obstruction or damage. This type of hearing loss can also be caused by a buildup of earwax in the ear canal.
Usually, the primary difficulty faced with conductive hearing loss is the sounds you are hearing are, quite simply, just not loud enough. The sensitive inner ear and auditory nerve are working correctly, so sounds tend to be clear, but not of adequate volume.
Medical intervention, and sometimes surgery, may be needed to fix the issue. However, If the hearing loss is caused by an abnormality like stenosis/narrowing of the ear canal or fused ossicles, the damage may be considered permanent and may need to be treated with traditional or bone conduction hearing aids.
Bone conduction hearing aids create vibrations that are sent across the skull to the inner ear, directly stimulating the cochlea where these vibrations are perceived as sound. So if there is an issue with the outer and middle ear components, the process of transmitting sound by air can be bypassed.
Some causes of conductive hearing loss include:
- Fluid in the middle ear
- Ear infection
- Stenosis or a narrowing of the ear canal
- Wax impaction
- Exostoses (bone-like protrusions that can develop inside the ear canal and cause potential blockages)
- Disconnected or fused ossicles
- Unusual growths or tumours
- Perforation or scarring of the eardrum
- Swimmers ear
- Mixed hearing loss
This is caused by a combination of sensorineural and conductive hearing loss issues and is very uncommon, although it can happen when the ear sustains some trauma. This type of hearing loss usually requires multiple forms of treatment as the sensorineural loss is most likely permanent, while the conductive hearing loss may be temporary or permanent.
Hearing loss can appear gradually or all of a sudden.
- Typically sudden hearing loss in one ear can be from earwax, an ear infection, a perforated eardrum, a tumour or Meniere’s disease.
- Sudden hearing loss in both ears may be caused by damage from a very loud noise, or a side effect of taking certain medications.
- Gradual hearing loss in one ear may be due to something inside the ear such as fluid, a growth (ostosclerosis) or a build up of skin cells (cholesteatoma).
- Gradual hearing loss in both ears is typically caused by aging or repeated exposure to loud noise.
Your hearing care professional will classify the extent and type of your hearing loss and make suggestions for treatment so you can start experiencing better hearing right away.
Click here to book a free hearing test now.
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