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→Sound Wave Propagation: A wrote a few more paragraphs using a differend source: Harris, N. Hemmerling, E. 1980. ''Introductory Applied Physics, Fourth Edition.'' Chapter 19. USA: McGraw-Hill, Inc
Reverberation is sound echoing and reechoing. Wallace Sabine measured reverberation in a lecture hall using a stopwatch. He then measured the effect of sound absorbing materials such as seat cushions. He found they reduced the duration of the reverberation. <ref name="Stevens & Warshofsky Chapter One" />
Reverberation is sound echoing and reechoing. Wallace Sabine measured reverberation in a lecture hall using a stopwatch. He then measured the effect of sound absorbing materials such as seat cushions. He found they reduced the duration of the reverberation. <ref name="Stevens & Warshofsky Chapter One" />
===Natural sound===
While the physiologist would say that sound has: pitch, loudness and quality, the physicist would say it has: frequency, intensity and overtones. A “sound source” is a vibration such as from a bell, drum, tuning fork, clarinet reed or piano wire. Sound is transmitted through a material medium – solid, liquid or gas – by molecules pushing those in front of them. Each molecule moves just a little as a wave moves through the material like on the surface of water only three dimensional. Where there is no solid, liquid or gas, sound is not transmitted by molecules pushing other molecules.<ref name="Harris & Hemmerling, Chapter 19">Harris, N. Hemmerling, E. 1980. ''Introductory Applied Physics, Fourth Edition.'' Chapter 19. USA: McGraw-Hill, Inc.</ref>
The speed of sound waves in air is much slower than the speed of light. One way it was timed was by looking at the flash of a gun and timing how long it took for the sound to be heard. It was calculated to be 1087 ft/sec at 32 F. The speed of sound increases as the temperature of the air increases: 1.1 ft/sec per 1 F. How far lightning is away can be calculated if the temperature is known, and physics books have such homework problems in them. Sound travels slowest in gasses and fastest in solids. Thus, sound speed is a property of the material the waves are in and the medium’s temperature.<ref name="Harris & Hemmerling, Chapter 19" />
===Supersonic sound===
As a bullet flies, air keeps moving out of the way causing sound waves. Two waves forming a V shape are caused by the projectile (described as if two dimensional). The V is wider when the projectile is moving slower. If the speed of the sound is known as well as the angle of the waves to the projectile (from a high speed movie camera) the speed of the projectile can be calculated using trigonometry.<ref name="Harris & Hemmerling, Chapter 19" />
On a larger scale, when a jet flies faster than sound moves through the air, it pushes the air molecules faster than sound waves would. The jet itself acts like sound waves. It is like more than one sound wave combined, resulting in a loud thundering sonic boom from the intense V wave of the jet passing by. The speed of a supersonic object divided by the speed of sound for that temperature is the Mach number. For example, Mach 1 is a speed. It is equal to about 770 mph.<ref name="Harris & Hemmerling, Chapter 19" />
===Music===
Music is different from noise in that is has a tune. Music contains distinct pitches. A high voice can sing high pitches and a low voice can sing low pitches. Savart’s wheel demonstrates that a regular frequency of vibration causes a definite pitch which could be notated, while irregularity of frequency has no definite pitch. Like, if you held the end of a playing card a little against the spokes of a bicycle wheel, a higher pitch would result when the wheel is moving faster.<ref name="Harris & Hemmerling, Chapter 19" />
==Sound patterns==
==Sound patterns==
===Beat===
===Beat===