Sound

:This article is about compression waves. For other meanings, see sound (disambiguation).

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Sound is vibration, as perceived by the sense of hearing. Vibrations usually travel to our ears through the air; the ear converts them into nerve impulses sent to our brains, where the impulses become sound.

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In more technical language, sound "is an alternation in pressure, particle displacement, or particle velocity propagated in an elastic material" (Olson 1957) or series of mechanical compressions and rarefactions or longitudinal waves that successively propagate through media that are at least a little compressible (solid, liquid or gas but not vacuum). In sound waves parts of matter (molecules or groups of molecules) move in a direction of the spreading of the disturbance (as opposite to transversal waves). The cause of sound waves is called the source of waves, e.g. a violin string vibrating upon being bowed or plucked.

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A sound wave is usually represented graphically by a wavy, horizontal line; the upper part of the wave (the crest) indicates a compression and the lower part (the trough) indicates a rarefaction.

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Pressure: Pressure is the amount of force applied normal to a surface divided by the area of that surface. As an example of varying pressures, a finger can be pressed against a wall without making any lasting impression; however, the same finger pushing a thumbtack can easily damage the wall. Although the f...

Particle displacement: Particle displacement or particle amplitude (represented in mathematics by the lower case Greek letter ξ) is a measurement of distance (in metres) of the movement of a particle in a medium as it transmits a wave. In most cases this is a longitudinal wave of pressure (such as sound), but it can a...

Particle velocity: Particle velocity is the velocity v of a particle (real or imagined) in a medium as it transmits a wave. In many cases this is a longitudinal wave of pressure as with sound, but it can also be a transverse wave as with the vibration of a taut string....

Sound related Images and Photos (experimental)

Chicago Sound	Sound Of Summer	Dixieland Sound	Pets Sound Puzzle
Farm Sound Blocks	Sound of Thunder, A (DVD) (WS)	Train Sound Puzzle	Milford Sound Lake
Marlborough Sound	Shapes Sound Puzzle	Sound of Colour I	Numbers Sound Puzzle