Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point. The oscillations may be periodic such as the motion of a pendulum or random such as the movement of a tire on a gravel road.

Vibration is occasionally "desirable". For example the motion of a tuning fork, the reed in a woodwind instrument or harmonica, or mobile phones or the cone of a loudspeaker is desirable vibration, necessary for the correct functioning of the various devices.

More often, vibration is undesirable, wasting energy and creating unwanted sound – noise. For example, the vibrational motions of engines, electric motors, or any mechanical device in operation are typically unwanted. Such vibrations can be caused by imbalances in the rotating parts, uneven friction, the meshing of gear teeth, etc. Careful designs usually minimize unwanted vibrations.

The study of sound and vibration are closely related. Sound, or "pressure waves", are generated by vibrating structures (e.g. vocal cords); these pressure waves can also induce the vibration of structures (e.g. ear drum). Hence, when trying to reduce noise it is often a problem in trying to reduce vibration.

Read more about Vibration:  Types of Vibration, Vibration Testing, Vibration Analysis, Multiple Degrees of Freedom Systems and Mode Shapes

Famous quotes containing the word vibration:

    In the very midst of the crowd about this wreck, there were men with carts busily collecting the seaweed which the storm had cast up, and conveying it beyond the reach of the tide, though they were often obliged to separate fragments of clothing from it, and they might at any moment have found a human body under it. Drown who might, they did not forget that this weed was a valuable manure. This shipwreck had not produced a visible vibration in the fabric of society.
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    All sound heard at the greatest possible distance produces one and the same effect, a vibration of the universal lyre, just as the intervening atmosphere makes a distant ridge of earth interesting to our eyes by the azure tint it imparts to it.
    Henry David Thoreau (1817–1862)