characteristics_of_sound by paydot888

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									characteristics of sound

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344

Summary:
Sound in brief but remarkeable terms is a vibration, that our ears
percieve by the sense of hearing. Most commonly vibrations travel to our
ears via the air. The ear then converts these sound waves into nerve
impulses that are sent to our brains, where the impulses become sound. To
say all that in a more technical language: Sound "is an alternation in
pressure, particle displacement, or particle velocity propagated in an
elastic material" (Olson 1957).


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Article Body:
Sound in brief but remarkeable terms is a vibration, that our ears
percieve by the sense of hearing. Most commonly vibrations travel to our
ears via the air. The ear then converts these sound waves into nerve
impulses that are sent to our brains, where the impulses become sound. To
say all that in a more technical language: Sound "is an alternation in
pressure, particle displacement, or particle velocity propagated in an
elastic material" (Olson 1957). Sound is also a series of mechanical
compressions and rarefactions or longitudinal waves that successively
propagate through media that are at least a little compressible. What
causes sound waves is known as "the source of waves". Examples of sounds
sources is: A violin string that vibrates upon being bowed or plucked.

The four characteristics of sound are frequency, wavelength, amplitude
and velocity.

The <b>frequency</b> of sound is the number of air pressure oscillations
per second at a fixed point occupied by a sound wave.

The <b>amplitude</b> is the magnitude of sound pressure change within the
wave. Basically this is the maximum amount of pressure at any point in
the sound wave. A sound wave is caused literally by increases in pressure
at certain points causing a "domino effect" outward, the higher pressure
points are the crests in a sound wave, and behind them are low pressure
points which tail them. These are known as the troughs on a wavelength
graph. Sound's propagation <b>Velocity</b> depends largely on the type,
temperature and pressure of the medium through which it propagates.
Because air is nearly a perfect gas, the speed of sound does not depend
on air pressure.

The frequency range of sound that is audible to humans is approx. between
20 and 20,000 Hz. This range of course varies between individuals, and
goes down as are age increases. Sounds will begin to damage our ears at
85 dBSPL and sounds above approximately 130 dBSPL will cause pain, as a
result are known as the: "threshold of pain". Of course again this range
will vary among individuals and will change with age.

								
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