A CATALOG OF SOUNDS

Normal sounds propagate through the air at sea level at a speed of about 1100 feet per second, or 750 miles per hour. Sounds travel faster in liquids, faster still in solids, and fastest of all in hot gases known as plasmas.

The fastest sounds propagate at supersonic speeds within a range of several thousand miles per second, to hypersonic speeds which approach the speed of light. The very fastest sounds are plasma waves which propagate in a low-density medium such as the upper atmosphere of a planet or the stellar wind, or high-density sounds which travel within the interior of stars, or are generated by chemical and nuclear reactions.

Slow sounds propagate at subsonic speeds, which range from several feet per second to several hundred feet per second.The slowest sounds form standing wave patterns in the place where they are generated. Standing waves do not travel through a medium like normal sound waves, but remain at or near their source, such as the wave patterns which are formed on the head of a drum. In a standing wave pattern, the frequency of the wave or waves is the same as it'straveling speed. The frequency and the velocity of the wave are identical because the wave is traveling through space in a recurrent, orbital path. Global standing wave patterns include large-scale geological, ecological, biological, social and cultural cycles. The very slowest sounds include the spins, orbits, beats, and lifecycles of the largest astronomical bodies, such as galaxies, intergalactic gas clouds, galactic groups, clusters, and superclusters.

The shortest sounds are those which can generate enough energy from a sound source to form a wave pattern.

Sounds with the longest duration are known as solitons. Solitons form atypical waves such as a tidal bore, which may travel for miles down a narrow river or stream. Normally, sound waves spread-out then disperse very quickly as the distance from their source increases. However, when the dispersion of the wave is exactly balanced by the tendency of the wave to narrow, the sound will keep on going.

 

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