natural harmonics
Ethereal, flute-like tones produced on string instruments by lightly touching the string at specific nodal points while bowing, allowing only certain overtones to sound.
In Depth
Natural harmonics are produced by lightly touching (not pressing) a string at specific fractional points — halfway, one-third, one-quarter, one-fifth, etc. — while bowing normally. This contact creates a node that divides the string into equal vibrating segments, suppressing the fundamental and lower overtones while allowing the targeted harmonic to ring clearly. The resulting tone is pure, transparent, and bell-like, with an ethereal quality quite different from normally stopped notes.
The most common natural harmonics occur at the octave (half string length), octave plus fifth (one-third), two octaves (one-quarter), and two octaves plus a major third (one-fifth). Artificial harmonics extend the technique by stopping the string with one finger while lightly touching with another, allowing harmonics at any pitch. Ravel was particularly fond of string harmonics — his String Quartet and orchestral works feature extensive harmonic writing. Modern composers use harmonics to create shimmering, spectral textures. The spectralist school (Grisey, Murail) built entire compositional systems around the harmonic series revealed through this technique.
The harmonic series produced by touching a string at fractional points follows exactly the same mathematical pattern as the overtone series — a physical demonstration of the fundamental relationship between mathematics and music that has fascinated scientists since Pythagoras.