Previous posts have focused on how sound travels along a string and how this relates to string instruments. In addition to traveling on strings, sound waves travel through air. This is not just critical for wind instruments, but for our entire perception of sound. To understand how sound travels through air, we must first understand what air is and why sound waves are able to pass through it.
Air is a collection of gas particles: mostly nitrogen with some oxygen and a small percentage of other gases, such as carbon dioxide. Like all materials in a gaseous state, particles in air are constantly moving, which creates pressure. As a sound wave passes through air, it creates localized changes in pressure. Condensations are areas of high pressure and rarefactions are areas of low pressure. These changes in pressure can be modeled well by a sine wave as sound passes through air. This process of creating condensations and rarefactions is how sound is able to travel from a vibrating string to your ear. It is also the driving force in the creation of sound in wind instruments where sound waves are not generated by vibrating strings, but by vibrating air particles in a chamber. The next post will feature the results of experiment that explores the way in which sound is able to be generated in a tube.
Works Cited:
1. Gunther, Leon. The Physics of Music and Color. New York, New York: Springer, 2012.
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