Soundwaves

Sound Waves: What produces sound?

Sound Intensity: Click here to see how too much sound can do harm!

The Larynx: How do we actually produce sound?

Sound is caused when vibrations causes air to vibrate which causes sound waves which are picked up by your eardrum causing it to vibrate which is translated by your brain into a sound.

Sound needs a medium to travel on egs. gases, solids or liquids. Sound travels in air at about 1,224 Km
It travels in water at about 5,400 Km much faster than air
An echo occurs when a sound bounces off a surface and bounces back to you.

A large vibration causes a large sound and a small vibration causes a small sound.
Sound can also be caused by energy. This energy causes vibration which causes sound.
Vibrations were used by indians to track buffalo they would put their ears to the ground to try and hear the buffalo.

Soft materials such as cottonwool absorb sound, this is why you cannot hear when you drop them.

An Ancient Greek Philosopher caled Aristotle believed that sound and light were carried through air like waves. He also said that they couldn't travel through a vacuum.Many centuries later (the 17th century) scientists could create a vacuum to test Aristotle's theory. An Irish scientist called Robert Boyle created an experiment in 1658. The experiment was that he pumped air from a jar that held a ticking watch. As there was less air left in the jar, he could not hear ticking at all. This proved Aristotle's theory correct.

Sound Intensity

Just as you would use centimetres to measure a science book, you would use decibles to measure the intensity of sound. In other words to measure how powerful sound is.

If something is 0 decibles it is not powerful enough to be heard.
Whispering is approximately 10 decibles.
Wind and leaves rustling is approximately 20 decibles.
Waves on the seashore measure approximately 40 deicibles.
A shouted conversation measures approximately 70 decibles.
A vacumn cleaner measures approximately 80 decibles.
Rock music music measures approximately 100 decibles.
A jet engine measures approximately 110 decibles.
The threshold of pain measures at 120 decibles!

So maybe Mum and Dad have a point when they say listening to loud rock music will make you deaf.

The Larynx.

The larynx is another name for the voice box. The larynx joins with the pharynx with the trachea. It is made up of nine parts of cartilage and it has two main parts. When you are swallowing the epiglottis which is the upper cartilage covers the voice box to stop food going into the lungs. Whenever you aren't swallowing food the epiglottis opens and the larynx opens as well.

The Larynx and Sound

The larynx plays an important part in voice production. Sound is produced when the vocal cords vibrate as air flows out of the lungs. The adam's apple is in front of the larynx. When boys reach puberty the larynx grows and that causes their voice to deepen.

Ultrasonics: What is it? If you were studying Physics you could study ultrasonics. Ultrasonics is the study of high-frequency sound waves.

Sound Waves: What are they? A vibrating object gives off sound waves and different vibrating objects can give off different amounts of sound waves.

Frequency: What is it? Frequency is the number of sound waves given off by a vibrating object. Frequency is measured in Hertz (or Hz for short) which is the number of sound waves given off by a vibrating object per second.

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