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Sound

{alt}Sound waves are like ripples on a pond{more}Click to play videoSound is a form of energy made when objects vibrate (move to and fro rapidly). As an object vibrates it sets the air around it vibrating, too: molecules of the gases in the air press close together and then pull apart. These regions of higher and lower air pressure move away from the source and are called sound waves. Sounds also travel through liquids and solids. Sound waves usually move away from the sound source in all directions, like ripples in a pond.



This illustration shows the many sources of sound you might hear in a typical street. Sounds can have different pitches. An...Read More >>This illustration shows the many sources of sound you might hear in a typical street. Sounds can have different pitches. An example of a low-pitched sound is the rumble of a jet or the beat of a pop song. Birdsong is a high-pitched sound. Sounds can also have different volumes. A very soft sound is a watch ticking or a leaf falling. A very loud sound is one made by a drill or a car tooting its horn.


As an object vibrates it sets the air around it vibrating, too: molecules of the gases in the air (represented here by blue...Read More >>As an object vibrates it sets the air around it vibrating, too: molecules of the gases in the air (represented here by blue balls) press close together (compression) and then pull apart (rarefaction). These regions of higher and lower air pressure are called sound waves. Compression corresponds to the crest of the wave, while rarefaction corresponds to the trough.

Sound waves

Sound waves travel as a series of alternating high and low pressure regions, called compressions and rarefactions. As they move, the distance between compressions and rarefactions remains the same. The distance between one compression and the next is the wavelength of the sound. The difference between the low pressure of a rarefaction and the high pressure of a compression is the amplitude of the sound wave. The greater the amplitude of the wave, the greater its energy.

Sound travels more than 10 times faster through solid steel than through the air.

WHY DO BIRDS
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