Fundamental

The fundamental is the lowest partial of a sound, and its frequency is the fundamental frequency, usually written f or f0. In a harmonic sound, all higher partials are whole-number multiples of it. Listeners usually hear the pitch as the fundamental, even when the fundamental is weak or missing, because the upper partials are spaced at its multiples. A telephone line, which passes little energy below about 300 Hz, still conveys the pitch of a low male voice through its upper partials. For a string sounding a note at 110 Hz, the fundamental is 110 Hz, and the octave, fifth and two octaves above it are the second, third and fourth partials. The fundamental is the only partial that is not an overtone.

Related terms

• PartialAny frequency, including the fundamental, that a sounding body vibrates at and that together make up its tone.
• Harmonic seriesThe whole-number multiples of a fundamental frequency, f, 2f, 3f and so on, which a string or air column sounds together.
• PitchThe perceived highness or lowness of a sound, which for most sounds follows its fundamental frequency.
• OvertoneAny partial sounding above the fundamental, which together with the fundamental shapes a sound's timbre.

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