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Standing Waves in Musical Instruments

المؤلف:  Will Raven

المصدر:  Atomic Physics for Everyone

الجزء والصفحة:  p-14

2026-11-10

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Fun Fact Many musical instruments make noise (hopefully pleasant noise!) because of standing waves. For example, when a guitarist plucks a guitar string, which is fixed at both ends, they are creating many standing waves (see Fig. 1) with different amplitudes all at the same time. Each of those standing waves has a frequency that is a multiple of the fundamental frequency. The amplitude of each of those standing waves is what gives the guitar it’s distinctive sound. To play a different note, the guitarist changes the length of the string by pressing on the string in a different spot, which in turn changes the fundamental frequency.a The same is true for a piano. A piano key strikes a wire that produces standing waves that result in a (hopefully!) pleasant noise. The amplitudes of all the standing waves on a struck piano wire are different than the amplitudes of a guitar string, which is why they sound different.

A note played on a trumpet or saxophone also produces standing waves, but the standing waves are created in the air and are physically manifested as places of high and low air density.

Fig. 1 The first three standing waves of a one dimensional rope or slinky. Each standing wave is drawn with the same amplitude A. Interestingly, the frequency of a standing wave is independent of the amplitude of the standing wave.