Pitch (music)

[2] Pitch is a major auditory attribute of musical tones, along with duration, loudness, and timbre.

Pitch is the subjective perception of a sound wave by the individual person, which cannot be directly measured.

The exact etymological history of the musical sense of high and low pitch is still unclear.

[4] When the actual fundamental frequency can be precisely determined through physical measurement, it may differ from the perceived pitch because of overtones, also known as upper partials, harmonic or otherwise.

For instance, a tone of 200 Hz that is very loud seems one semitone lower in pitch than if it is just barely audible.

[13] Later investigations, e.g. by A. Cohen, have shown that in most cases the apparent pitch shifts were not significantly different from pitch‐matching errors.

When averaged, the remaining shifts followed the directions of Stevens's curves but were small (2% or less by frequency, i.e. not more than a semitone).

A place code, taking advantage of the tonotopy in the auditory system, must be in effect for the perception of high frequencies, since neurons have an upper limit on how fast they can phase-lock their action potentials.

[5] However, a purely place-based theory cannot account for the accuracy of pitch perception in the low and middle frequency ranges.

The precise way this temporal structure helps code for pitch at higher levels is still debated, but the processing seems to be based on an autocorrelation of action potentials in the auditory nerve.

[5] At least one model shows that a temporal delay is unnecessary to produce an autocorrelation model of pitch perception, appealing to phase shifts between cochlear filters;[17] however, earlier work has shown that certain sounds with a prominent peak in their autocorrelation function do not elicit a corresponding pitch percept,[18][19] and that certain sounds without a peak in their autocorrelation function nevertheless elicit a pitch.

[20][21] To be a more complete model, autocorrelation must therefore apply to signals that represent the output of the cochlea, as via auditory-nerve interspike-interval histograms.

[4] The just-noticeable difference (jnd) (the threshold at which a change is perceived) depends on the tone's frequency content.

[22] The jnd is typically tested by playing two tones in quick succession with the listener asked if there was a difference in their pitches.

Whether or not the higher frequencies are integer multiples, they are collectively called the partials, referring to the different parts that make up the total spectrum.

In modern times, they conventionally have their parts transposed into different keys from voices and other instruments (and even from each other).

For example, one can adopt the widely used MIDI standard to map fundamental frequency, f, to a real number, p, as follows.

In well-tempered systems (as used in the time of Johann Sebastian Bach, for example), different methods of musical tuning were used.

If however the first overtone is sharp due to inharmonicity, as in the extremes of the piano, tuners resort to octave stretching.