The senses of sight and sound are probably the most important senses. Can you imagine what life would be like if you are deprived of these senses? People who have lost the sense of sight live in a world of perpetual darkness while people who have lost the sense of sound live in a world of total muteness. In other words, they become blind or deaf.
The sense of sight makes it possible for people to see. Human beings and animals use their eyes to see. The sense of sound allows people to hear. They do this with the ears. Now, you know why the eyes and the ears are so important. Let's learn about how they work.
The simplest way to explain how the eyes work is to think of them as video cameras. When the eyes are open, they are working. Sight begins when beams of light from object or objects go through the cornea to enter the eye. As the light rays each the pupil, the iris adjusts the size of the pupil to accommodate the amount of light. After this, the light rays go into the lens where the image is focused onto the retina through the vitreous humor. The retina is composed of some 150 million light-sensitive cells which are known as rods and cones. Working best in low light levels, rods make out the shapes. Conversely, cones work best in high light levels and they identify color. Via the optic nerve, the information is then sent to the brain. The brain then converts the inverted image right-side up in the visual cortex, letting you know what you are seeing.
When a sound is made, sound waves travel through the air. The outer ear then captures these vibrations, funneling them into the ear canal. Entering the middle ear, the vibrations cause the eardrum to vibrate too, setting off a whole sequence of vibrations. The vibrations from the eardrum hit the hammer and the anvil before hitting the stirrup. Next, the stirrup transmits the vibrations into the cochlea in the inner ear. There are thousands of cilia (hair-like nerve endings) in the liquid-filled cochlea. As the liquid in the cochlea vibrates, the cilia move and convert these vibrations into messages, passing them through the auditory nerve into the brain. In the brain, the messages are deciphered so you know what you are hearing. Other than hearing, the ears also help people to keep their balance.
Below are more educator materials which further explain how the eye and ear work.