Mon Prof Augmenté
How a String Splits Into Harmonics
Age 15 · Music
A plucked string can vibrate as one whole arc or in 2, 3, 4 or more equal parts, separated by still points called nodes, and each split adds a higher note called a harmonic. When the vibrating part is half as long, it vibrates twice as fast and sounds exactly one octave higher.
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Age 15: open this week
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In the picture
- Fundamental: the whole string vibrates in one arc and gives the lowest note
- Second harmonic: two equal halves with a still point in the middle, one octave higher
- Third harmonic: three equal thirds, three times the fundamental frequency
- Fourth harmonic: four equal quarters, two octaves above the fundamental
Examples
- A guitarist lightly touches a string exactly above the 12th fret, at its midpoint, and gets a bell-like note one octave higher.
- Pressing a guitar or violin string halfway along its length makes it sound the same note, one octave up.
Key takeaways
- Halving the length of a vibrating string doubles its frequency, which raises the note by one octave.
- Harmonics split the string into whole-number equal parts, giving frequencies of 2, 3, 4… times the fundamental.
Quiz: How a String Splits Into Harmonics (Age 15)
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If the vibrating part of a string is made half as long, what happens to its note?
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In the third harmonic, how does the string’s frequency compare with the fundamental?
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When a string vibrates in harmonics, how does it divide?
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