Norbert-Sound

After sight, hearing is the sense that provides the brain with most information about the surroundings. Then human ear can register a wide range of sounds compared to animals. This system, the auditory system, also gives us the sense of balance. 

Balancing 

Head movement swirl fluid insde the semicircular canals. They are sensory cells that fire nerve signals to the brain. They are arranged in pairs and each detects motion in one of the three dimensions. 

Atmospheric Pressure 

The Eustachian tube allows air from the throat to flow into the middle ear cavity, so as atmospheric pressure changes, the air pressure on either side of the eardrum can equalize, allowing the eardrum to vibrate without any restrictions. This is why our ear ‘pops’ when we go downhill, because the pressure is increasing. 

Hearing 

Sound waves funnel into the canal and strike the eardrum. Then vibrations are created. The movement travels along then three tiny ear bones, ossicles. They span in the middle ear and are our body’s smallest bones. They contract when sound hits the eardrum. The ossicles vibrate the oval window into the cochlea. Then the membrane shake, which then pulls microscopic hairs, and the hairs transfer nerve signals to the brain. 

Damage 

The Royal National Institute for Deaf People accused manufactures of MP3 players failed to put warning messages on the packaging to urge customers not to crank the volume to high up. They also recommended customers should invest in in-ear canal filters or noise-isolating headphones, thus reducing the need to increase volume.

It was also found that 58% of those surveyed was unaware of any risk when using MP3 players and 79% claimed they haven’t seen any warning on volume levels on the packaging when purchasing their MP3 player.

http://en.wikipedia.org/wiki/Ear

http://news.bbc.co.uk/2/hi/health/6982184.stm

Book: '€˜Human Body'€™ Author: Steve Parker

Touch -- Zoha

Everything humans do involves using one or more senses. It is through the senses that infants discover the world. Humans experience these sensations through interactions with the environment; interpreting the meaning of these sensations for actions is called sensory processing.

Touch is our oldest, most primitive and pervasive sense. It's the first sense we experience in the womb and the last one we lose before death Not only does the skin have a main job of protecting the young infant, but it also exposes the infant to the sense of touch. It lets your infant feel it's way around and feel the differences between a soft blanket and a hard wood floor.

Touch may be considered one of five human senses; however, when a person touches something or somebody this gives rise to various feelings: the perception of pressure (hence shape, softness, texture, vibration, etc.), relative temperature and sometimes pain. Thus the term "touch" is actually the combined term for several senses. In medicine, the colloquial term "touch" is usually replaced with somatic senses, to better reflect the variety of mechanisms involved.

http://social.jrank.org/pages/557/Sensory-Development-Touch.html
http://en.wikipedia.org/wiki/Somatosensory_system

Chloe Chan: Smell

Our sense of smell is valuable and powerful, it contributes to discreet parts of our lives. Smell plays a major role to taste, without it we cannot tell if something tastes delicious or not because we can only taste sweet, salty, bitter, sour.

Our noses warm, moisten and filters the air we breathe, it also has the ability to smell odors. Odor molecules inhaled float upwards towards two small areas at the top of the naval cavity. This area is covered with 5 million tiny nerve cells which can detect 10,000 different smells. Nerves cells are different shapes and only specific molecules can fit them. Our cells send signals to the brain allowing us to recognize particular odors.

We naturally have preferences for certain smells. Our preference for certain smells has much to do with our past experiences and what we are used to as a child. It is so powerful that it can alter our preference of people and places, most of the time this happens unconsciously. As well as these things, smell can alert us to things such as danger when we smell gas. Evidently our sense of smell plays a very wide role in our lives.

http://yucky.discovery.com/flash/body/pg000150.html
http://www.sirc.org/publik/smell_human.html
http://www.senseofsmell.org/feature/odor/odor_whitepaper_1.php

Ming Fung: Touch

People might think our skin is the organ of the sense of touching. However it is the sensory receptors that does the job, there are more than 4 million of these things in our skin. This system detects experiences such as touch or pressure, temperature (that;s why we feel cold), pain, itch, tickle, etc... When someone touches something, we get perception of the pressure, therefore we can make out what is the object we are touching, like texture, shape, etc...

When we touch, signals go through things called neurons to the brain. Which the brain determines what we are touching, telling us what we are feeling and how it feels. If we get burnt by flame, the signal is too urgent to be sent to the brain, but stops half way at the spinal cord. This gives a fast reaction, moving away from the thing that is hurting us.

Source: http://www.wikipedia.com/ http://www.askjeeves.com/ http://www.answerbag.com/

Robert Win - Sound

How are we able to hear things?

People are able to hear sound frequencys from 20 - 20,000 Hz using their Ears and the organs within, as well as the Brain. Our outer ears which stick out from the sides of our heads, are like noise cones which receive and channel sounds to travel down the ear canal. When sound reaches the Ear drum, it vibrates the ear-drum, at the frequency of the orginal sound (every sound has a different frequency, unless they are identical sounds). The vibrations are converted by the cochlea, which is a snail like shaped organ which is filled with fluid, into signals which can be sent and read by the brain. The brain then decodes and reads the signals, and that is how we are able to hear things, and distinguish one sound from another.

Information provided by: http://www.wikipedia.com/, http://www.discovery.com/ and http://www.askjeeves.com/

Hey Tou Chiu: Sight

When asked the question “How do we see?” many would say – “we use our eyes!” This is true; however the eye is not as simple as it looks.

We see things when we process the light rays that reflect into our eye. The light rays first pass through the surface of our eye (cornea) and then to through the pupil. Here the pupil can regulate the amount of light that can pass through into the inside of the eye. If the outside environment is dim, more light will be allowed to pass through to enable us to see clearly. On the other hand, if the outside environment is bright, then the pupil will allow less light to the back of our eye – the retina. The rays of light then become electric impulses and get sent to the brain to be processed and we are then able to see.

Some people may ask – “How do we see color?” The answer is simple. There are photo receptor cells in the retina which respond to dim light and color. They are known as rod and cone cells. Others may also wonder why we can still see an upright image when the image created on our retina is actually inverted. This is actually because our brain “knows” that the picture on our retina is inverted which is not what we usually sees, so it “adjusts” the picture so that we can see it with the right way up.