The overtone series, or harmonic series, is a progression of natural frequencies related to a fundamental frequency in whole-number ratios. If you listen to a musical chord or sound, the lowest and most dominant tone is the fundamental frequency, and the higher-pitched tones are the overtones. Physics relies heavily on the overtone series to describe the resonances and vibrations of everyday objects, including musical instruments.
Each overtone in the overtone series is the next whole-number multiple of the fundamental frequency. If the fundamental frequency is 100 hertz, the first overtone would be 200 hertz (the second harmonic), the second overtone would be 300 hertz (the third harmonic), and so on. The term “harmonic series” is used because each overtone in the sequence is likewise called a “harmonic.”
Sound waves and their interactions with various materials can be better understood by looking at the overtone series. The shape and length of a tube, like the body of a wind instrument, affect which overtones are enhanced and which are suppressed by the passage of a sound wave through the tube. As a result, the instrument’s tone will change. The natural resonances of a guitar string can also be explained using the overtone series, as can the way a singer’s formant resonances affect the sound they produce.
In addition to its use in physics, the overtone series has important applications in music theory and composition. One type of consonant chord is the harmonic chord, which consists of tones from the overtone series rather than the traditional chord notes. It’s also possible to make melodies and chord progressions by using the interplay between various harmonics.
Fundamental to acoustics, music theory, and physics is the idea of the overtone series. It’s useful for understanding the physics behind things like musical instruments’ innate resonances and vibrations. A more complete appreciation of music, from the construction of musical instruments to the writing of songs, can be gained through a better grasp of the overtone series.