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Vibration, or oscillation, is a periodic movement in time of a system around a certain equilibrium position. The system consists of at least an element for storing kinetic energy and one for storing potential energy. The vibration is a process of energy-type exchanges between the kinetic and potential energies. The equilibrium position is the state in which the potential energy becomes zero. The periodicity of the movement is described in frequency which is the measurement of the numbers of times the repeated events that occurred in a unit time. Vibration is an omnipresent type of dynamic behavior of a system and exists in many forms, such as sound and music. Human beings first recognized the vibration phenomenon by entertaining themselves with percussion, string, and plate music instruments in ancient times. Just like the time when the lever principle was discovered is much later than that of its real utilization in human history, the time when the vibration and acoustics theory on the principles of the music instruments were discovered is much later than that of the music instruments were made and played. The earliest music instrument unearthed in Henan Province, China, is a bone flute, which can be traced back about 6000–5000 years B.C., while the earliest string vibration frequency and music acoustic theory for a string instrument ever written and published in Chinese history is around 700 B.C. in “Guanzi” byGuan Zhong (723–645 B.C.). In hismusic-scale algorithm, if the length of the basic string for the major tone is 1, the string lengths of the next scales are either added 1/3 (4/3) of the basic length or subtracted 1/3 (or 2/3), other music scales are determined by this 1/3 length rule, and he obtained five tones by this algorithm: C, D, E, G, A. It’s amazing that more than 100 years later the Greek Philosopher and Mathematician Pythagoras (570–504 B.C.) discovered independently the very similar theory for seven tones: The Pythagorean scale.