Pitch / Fundamental Frequency

Pitch is a perceptual property of a sound that lets us classify tones as higher or lower. For a sustained tone from a single voice or instrument, pitch corresponds closely — but not identically — to the fundamental frequency: the lowest frequency in a periodic signal, of which all the harmonics are integer multiples.

The Distinction Between Pitch and Fundamental Frequency

The fundamental frequency is a measurable physical property of the signal. The pitch is what a human listener actually hears, and the two can drift apart for several reasons:

  • Two listeners can disagree about the pitch of the same sound, especially if it is short, noisy, or in an unusual register.

  • The ear can perceive a pitch even when the corresponding frequency is missing from the signal — the missing fundamental effect. If only the 2nd, 3rd, and 4th harmonics of 100 Hz reach the ear, most listeners still hear the pitch as 100 Hz.

  • Sounds whose components are not on a harmonic series — singing bowls, bells, chimes — may have no single defensible pitch. Different listeners, and different analyzers, will give different answers.

For most singing and most pitched instruments, the perceived pitch and the harmonic fundamental coincide closely enough that the two terms can be used interchangeably.

How VoceVista Estimates Pitch

To estimate pitch, the analyzer looks for periodicity in the signal — in effect, asking "what is the fundamental frequency of which the prominent peaks are integer multiples?" When the signal is clean and harmonic, this is reliable. The estimate becomes less stable on:

  • unvoiced consonants and other noise-like sounds, where there is no periodicity;

  • very low or very high pitches near the limits of the analyzer’s range;

  • polyphonic material with two or more independent voices.

In these cases the displayed pitch line may flicker, jump, or disappear; the spectrogram remains an honest record of what the signal contains, even where the pitch estimate fails.

In VoceVista

The estimated pitch is overlaid on the Analyzer View and can be turned on or off there. The expected pitch range can be configured in Fundamental Ranges, which helps the analyzer avoid octave errors when tracking very low or very high voices.