The eardrum separates the outer ear from the middle ear and the ossicles. The ossicles are the three tiny delicate bones that help move sound along into the inner ear.
When the sound waves reach the ear drum it vibrates, causing the tiny bones to move. These bones are called
- The malleus which is attached to the eardrum and means “Hammer” in Latin.
- The incus, which is attached to the malleus and means “Anvil” in Latin.
- The stapes, the smallest bone in the body is attached to the incus and means “stirrup” in Latin. (Appendix 1)
The inner ear
The sounds come into the inner ear as vibrations and enter the cochlea, a small curled up tube in the inner ear. The cochlea is filled with liquid, which is set into motion, like a wave, when the ossicles vibrate. The cochlea is also lined with tiny cells covered in tiny hairs that are so small you would need a microscope to see them. When the vibrations reach the cochlea they cause hairs on the cells to move, creating nerve signals that the brain understands as sounds.
Balance
In the inner ear, there are three small loops above the cochlea called semicircular canals. Like the cochlea they are also filled with liquid and have millions of tiny microscopic hairs. When you move your head the liquid in the semicircular canals move too. The liquid moves the tiny hair, which sends a never message to the brain about the position of your head in less then a second, your brain sends messages to the right muscles so you keep your balance.
Some the liquid in the semicircular canals keeps moving after you’ve stopped moving, this causes you to feel dizzy because the hairs in the canals still sense movement your brain gets two different messages and is confused about the position of your hear. Once the fluid stops moving, your brain gets the right message and you regain your balance.
Hearing loss and the cause
Hearing loss or impairment happens when there is a problem with one or more parts of the ear or ears someone who has loss of hearing maybe able to some sounds or nothing at all. About one thousand babies are born with hearing impairment making it one of the most common birth defects but hearing problem can also develop later in life.
There are a few different types of hearing loss, conductive, sensory, mixed and neutral.
Conductive hearing loss
This happens when there is a problem with a part of the outer or middle ear. Conductive hearing loss is usually temporary as in most cases medical treatment can help.
Sensory hearing loss
This happens when the cochlea is not working correctly because the tiny cells are damaged or destroyed. Sensory hearing impairment is almost always permanent and effect the ability to talk normally as there is little or no sound.
Neutral hearing loss
This happens when there is a problem with the connection from the cochlea to the brain. Neutral means related to nerve, so neural hearing loss means the nerve that carries the message to the brain from the cochlea is damaged.
The cause of hearing loss
Hearing loss can happen because a person was born with parts of the ear that didn’t form correctly and don’t work well. Other problems can happen later because if an injury or illness, including:
- Middle ear fluid.
- Serious infections, such as meningitis.
How Is Hearing Loss Treated?
Firstly your hearing is tested by an audiologist who uses an audiogram(appendix 2)to see whether or not hearing loss is detectable and from the finding on this treatment depends on the type of hearing loss, how severe it is, and the persons other needs. Common treatments include medicine, operations, hearing aids, or assistive listening devices, which emphasize voices and help the person hear better in noisy settings. With treatment, most people will be able to hear normally again.
Hearing aids are kind of like tiny microphones. They help someone hear sounds better and can even pick up the sounds so that what is hear is more clear. Hearing aids deliver amplified sounds (via sound vibrations) from the eardrum and middle ear to the inner ear or cochlea. Hearing aid technology is available that can adjust the volume of sounds automatically.
For some people who are not able to hear or understand words even with the help of hearing aids, there is a device called a cochlear implant. This is a very tiny piece of electronic equipment that is put into the cochlea during an operation. It takes over the job of the damaged or destroyed hair cells in the cochlea by turning sounds into electrical signals that stimulate the hearing nerve directly.
