Partial, harmonic, and overtone are distinct spectral terms: a harmonic is an integer-multiple partial, an overtone is any harmonic above the fundamental

These three terms are often used interchangeably but have precise, distinct meanings. A partial is any member of a spectrum — it may be harmonic or inharmonic. A harmonic is a partial whose frequency is an integer multiple of the fundamental: in a harmonic spectrum the fundamental sits at f, with harmonics at 2f, 3f, 4f…, so the fundamental is the greatest common divisor of all component frequencies. An overtone is any harmonic above the fundamental, so the first overtone equals the second harmonic. When components are not integer multiples of the fundamental, the sound is inharmonic (non-harmonic) and its components are inharmonic partials. Harmonic spectra produce a clear sense of pitch; inharmonic spectra (bells, gongs, metallic percussion) produce bell-like or noisy timbres. The distinction matters for synthesis: harmonic additive synthesis yields pitched sounds, while inharmonic spectra yield bell-like or noisy timbres, and in FM the sidebands are harmonic or inharmonic depending on the carrier-to-modulator ratio.

Examples

A sawtooth wave has only harmonic partials (f, 2f, 3f…); its first overtone is the second harmonic. A guitar string at 110 Hz has harmonics at 220, 330, 440 Hz — harmonic, clear pitch. A bell has inharmonic partials (e.g. 200, 520, 860 Hz) — non-harmonic, metallic. A drum may have both. FM sidebands can be harmonic or inharmonic depending on the C:M ratio.

Assessment

Given partials at 100, 200, 280, 300, 400 Hz with fundamental 100 Hz, identify which are harmonics and which are inharmonic partials, and name the first overtone. Given a spectrum at 150, 300, 600, 900 Hz, identify the fundamental and classify the sound as harmonic or non-harmonic.