The+Eye+&+The+Ear

= = =__The Eye & The Ear__=

The ear is a very sensitive part of the body and picks up very faint sounds. the ear is divided into three parts;

Outer ear- Is the part of the ear that can actually be seen, it consists of the pinna, ear drum, and the auditory canal.
Middle ear- the middle ear; hammar, anvil, stirrup and the oval window.

Inner ear- where those vibrations are changed into the signal that is carried to your brain. in the inner ear; Cochlea, ausitoy nerve, semicircular canals and eustachian tubes.

How do we hear?

Sound (as waves) enters your ear canal and hits your ear drum. This makes it vibrate. the sound waves travel through the outer ear and into the middle ear, three tiny bones in your middle ear link the vibrating ear drum with the inner part of your ear.

Why are our ears positioned at the side of our heads?
By having our ears separated by about 8 - 10, our brains can use the timing differences between each ear to locate sounds spatially.

What are safe levels of sound for our hearing?
The hearing cells in your inner ear can tolerate no more than 85dB of sound for 8 hours before permanent damage starts to occur. Sounds of 100dB can causdamage in just over 15 minutes and sounds of 103dB in just 7 minutes 30 seconds

What is a cochlear implant? How does it work?
A implant has the following parts:

> >
 * A microphone
 * A speech processor
 * A transmitter
 * An electrode array

A cochlear implant is a small device that can help to provide a sense of sound to a person who is slightly deaf. The implant consists of an external portion that sits behind the ear and a second portion that is surgically placed under the skin.



Types of hearing aids
There are many types of hearing aids (also known as hearing instruments), which vary in size and power. Among the different sizes and models are;
 * **Behind the ear aids**
 * **Body worn aids**
 * **Receiver In the Canal/Ear**
 * **Invisible In canal hearing aids**
 * **Disposable hearing aids**
 * === Eyeglass aids  ===

A hearing aid is an electroacoustic device which typically fits in or behind the wearer's ear, and is designed to amplify and modulate sound for the wearer.



=__The Eye__=

How does the eye focus light?
Our eye focus's on light by the muscles in the eye change the length and thickness of the retina.

**What causes short and long sightedness?**
Long sightedness; May be because your eyeball is too short, your cornea isn't curved enough or your lens isn't thick enough. You may find that close objects seem fuzzy or blurred. Distant objects won't look blurred because the light rays don't need as much focusing power, so they focus on your retina properly. Short sightedness; may be because your cornea is too curved or your eyeball is too long, meaning that light rays from distant objects focus in front of your retina. This makes distant objects seem fuzzy or blurred.



**What causes colour blindness?**
Most colour cause of blindness is if your born with it,Inherited color blindness happens when you don't have one of these types of cone cells or they don't work right. You may not see one of these three basic colors, or you may see a different shade of that color or a different color. This type of color vision problem doesn't change over time.

What are corneal transplants? Why are they needed?
They are for when theres damage to the cornea causes a drop in vision, or pain that interferes with daily activities such as driving, reading or working at a computer.

== Do all organisms have the same amount of lenses in their eyes? Which organisms have more or less than humans? == Compared to human eyes, the eyes of insects are considerably different. Their structures come in one of two types, simple or complex. Simple-structured eyes are round and small, capable only of separating light and dark.A human eye's lens can change shape, letting us focus on objects at various distances. The lens in an insect's eye cannot change shape, however, and so insects cannot focus.

== Do other animals see colour differently to humans? Why or why not? Give an example of an animal that sees colour differently and why? == Most likely every animal sees colour and things differently then humans,butterflies and bees can see UV rays, and flowers actually use this so that these insects will pollinate them.

A blind spot is when there is a part or area of your surroundings that is block by something and therefore you cannot see that area. Blind spots occur when driving and you cannot see what is behind you.
 * What is the blind spot? **