Hearing & Hearing Loss
How do we hear?
Hearing relies on a number of events that change sound waves in the air into electrical signals. Our auditory nerve then carries these signals to the brain through a complex series of steps:
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Sound waves enter the outer ear and travel through the ear canal that leads to the eardrum.
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The eardrum vibrates from the incoming sound waves and sends these vibrations through three tiny bones in the middle ear. The middle ear is a small air filled cavity beyond the eardrum.
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The bones in the middle ear amplify, or increase, the sound vibrations and send them to the inner ear that is shaped like a snail and is filled with fluid. An elastic membrane runs from the beginning to the end of the cochlea, splitting it into an upper and lower part. This membrane is called the "basilar" membrane because it serves as the base, or ground floor, on which key hearing structures sit.
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The sound vibrations trigger the fluid inside the cochlea to ripple, and a traveling wave forms along the basilar membrane. On this membrane are microscopic hair cells that move up and down as the membrane moves.
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As the hair cells move up and down, their bristly structures bump up against an overlying membrane and tilt to one side. This tilting action causes pore-like channels, which are on the surface of the bristles, to open up. When that happens, certain chemicals rush in, creating an electrical signal.
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The auditory nerve carries this electrical signal to the brain that translates it into "sound" that we recognize and understand.
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Hair cells near the base of the cochlea detect higher-pitched sounds, such as a bell or a whistle. Those nearer the apex detect lower-pitched sounds, such as a large dog barking.
Why Does Hearing Loss Happen?
Hearing loss happens for many reasons. In most cases, hearing loss results from damage to the inner ear.
The most common cause of this damage to the inner ear is aging. This condition is called prescycusis and is the general wear and tear on the hairs or nerve cells in the inner ear that send sound signals to the brain. When these hairs or nerve cells are damaged or missing, electrical signals aren't transmitted as efficiently, and hearing loss occurs.
One in three people older than sixty and half of those older than eighty five have hearing loss due to ageing. According to the charity Deafness Research UK, age-related hearing loss normally begins at around fifty.
The second most common cause of hearing loss is exposure to industrial noise or too much loud music. The popularity of iPods and other personal music systems may be behind an increasing numbers of young people who are losing their hearing.
What is the early signs of hearing loss?
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Do other people seem to mumble?
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Is it sometimes difficult to hear other people’s voices in a noisy pub or restaurant where others seem to manage quite well?
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Do you find other people’s TV or radio volume too low for you to hear clearly?
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Do other people comment that your TV or radio is too loud for them?
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Do you sometimes misunderstand what others are saying to you?
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Do you find yourself ‘filling in the gaps’ when you have misheard what someone has said to you?
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Do you often have to ask others to repeat what they have said to you?
The high frequency sounds are the often first to go when a hearing loss develops. This leads not to a lack of volume as such, but to speech sounding less distinct. So, while you may still hear someone talking, you may think they are mumbling and not be able to make out exactly what is being said. Increasingly finding yourself in such a situation can become difficult, and over time, you may withdraw and begin to feel isolated.
If you suspect you may suffer with hearing loss, it is advisable to have a hearing test with an Audiologist or Hearing Aid Dispenser.
