Pitch (music)

From Wikipedia for FEVERv2
Jump to navigation Jump to search

Pitch is a perceptual property of sounds that allows their ordering on a frequency-related scale, or more commonly, pitch is the quality that makes it possible to judge sounds as "higher" and "lower" in the sense associated with musical melodies. Pitch (music)_sentence_0

Pitch can be determined only in sounds that have a frequency that is clear and stable enough to distinguish from noise. Pitch (music)_sentence_1

Pitch is a major auditory attribute of musical tones, along with duration, loudness, and timbre. Pitch (music)_sentence_2

Pitch may be quantified as a frequency, but pitch is not a purely objective physical property; it is a subjective psychoacoustical attribute of sound. Pitch (music)_sentence_3

Historically, the study of pitch and pitch perception has been a central problem in psychoacoustics, and has been instrumental in forming and testing theories of sound representation, processing, and perception in the auditory system. Pitch (music)_sentence_4

Perception Pitch (music)_section_0

Pitch and frequency Pitch (music)_section_1

Pitch is an auditory sensation in which a listener assigns musical tones to relative positions on a musical scale based primarily on their perception of the frequency of vibration. Pitch (music)_sentence_5

Pitch is closely related to frequency, but the two are not equivalent. Pitch (music)_sentence_6

Frequency is an objective, scientific attribute that can be measured. Pitch (music)_sentence_7

Pitch is each person's subjective perception of a sound wave, which cannot be directly measured. Pitch (music)_sentence_8

However, this does not necessarily mean that most people won't agree on which notes are higher and lower. Pitch (music)_sentence_9

The oscillations of sound waves can often be characterized in terms of frequency. Pitch (music)_sentence_10

Pitches are usually associated with, and thus quantified as, frequencies (in cycles per second, or hertz), by comparing the sounds being assessed against sounds with pure tones (ones with periodic, sinusoidal waveforms). Pitch (music)_sentence_11

Complex and aperiodic sound waves can often be assigned a pitch by this method. Pitch (music)_sentence_12

According to the American National Standards Institute, pitch is the auditory attribute of sound according to which sounds can be ordered on a scale from low to high. Pitch (music)_sentence_13

Since pitch is such a close proxy for frequency, it is almost entirely determined by how quickly the sound wave is making the air vibrate and has almost nothing to do with the intensity, or amplitude, of the wave. Pitch (music)_sentence_14

That is, "high" pitch means very rapid oscillation, and "low" pitch corresponds to slower oscillation. Pitch (music)_sentence_15

Despite that, the idiom relating vertical height to sound pitch is shared by most languages. Pitch (music)_sentence_16

At least in English, it is just one of many deep conceptual metaphors that involve up/down. Pitch (music)_sentence_17

The exact etymological history of the musical sense of high and low pitch is still unclear. Pitch (music)_sentence_18

There is evidence that humans do actually perceive that the source of a sound is slightly higher or lower in vertical space when the sound frequency is increased or reduced. Pitch (music)_sentence_19

In most cases, the pitch of complex sounds such as speech and musical notes corresponds very nearly to the repetition rate of periodic or nearly-periodic sounds, or to the reciprocal of the time interval between repeating similar events in the sound waveform. Pitch (music)_sentence_20

The pitch of complex tones can be ambiguous, meaning that two or more different pitches can be perceived, depending upon the observer. Pitch (music)_sentence_21

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. Pitch (music)_sentence_22

A complex tone composed of two sine waves of 1000 and 1200 Hz may sometimes be heard as up to three pitches: two spectral pitches at 1000 and 1200 Hz, derived from the physical frequencies of the pure tones, and the combination tone at 200 Hz, corresponding to the repetition rate of the waveform. Pitch (music)_sentence_23

In a situation like this, the percept at 200 Hz is commonly referred to as the missing fundamental, which is often the greatest common divisor of the frequencies present. Pitch (music)_sentence_24

Pitch depends to a lesser degree on the sound pressure level (loudness, volume) of the tone, especially at frequencies below 1,000 Hz and above 2,000 Hz. Pitch (music)_sentence_25

The pitch of lower tones gets lower as sound pressure increases. Pitch (music)_sentence_26

For instance, a tone of 200 Hz that is very loud seems one semitone lower in pitch than if it is just barely audible. Pitch (music)_sentence_27

Above 2,000 Hz, the pitch gets higher as the sound gets louder. Pitch (music)_sentence_28

These results were obtained in the pioneering works by S.Stevens and W.Snow. Pitch (music)_sentence_29

Later investigations, i.e. by A.Cohen, had shown that in most cases the apparent pitch shifts were not significantly different from pitch‐matching errors. Pitch (music)_sentence_30

When averaged, the remaining shifts followed the directions of Stevens' curves but were small (2% or less by frequency, i.e. not more than a semitone) Pitch (music)_sentence_31

Theories of pitch perception Pitch (music)_section_2

Theories of pitch perception try to explain how the physical sound and specific physiology of the auditory system work together to yield the experience of pitch. Pitch (music)_sentence_32

In general, pitch perception theories can be divided into place coding and temporal coding. Pitch (music)_sentence_33

Place theory holds that the perception of pitch is determined by the place of maximum excitation on the basilar membrane. Pitch (music)_sentence_34

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. Pitch (music)_sentence_35

However, a purely place-based theory cannot account for the accuracy of pitch perception in the low and middle frequency ranges. Pitch (music)_sentence_36

Moreover, there is some evidence that some non-human primates lack auditory cortex responses to pitch despite having clear tonotopic maps in auditory cortex, showing that tonotopic place codes are not sufficient for pitch responses. Pitch (music)_sentence_37

Temporal theories offer an alternative that appeals to the temporal structure of action potentials, mostly the phase-locking and mode-locking of action potentials to frequencies in a stimulus. Pitch (music)_sentence_38

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. Pitch (music)_sentence_39

However, it has long been noted that a neural mechanism that may accomplish a delay—a necessary operation of a true autocorrelation—has not been found. Pitch (music)_sentence_40

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; however, earlier work has shown that certain sounds with a prominent peak in their autocorrelation function do not elicit a corresponding pitch percept, and that certain sounds without a peak in their autocorrelation function nevertheless elicit a pitch. Pitch (music)_sentence_41

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. Pitch (music)_sentence_42

Some theories of pitch perception hold that pitch has inherent octave ambiguities, and therefore is best decomposed into a pitch chroma, a periodic value around the octave, like the note names in western music—and a pitch height, which may be ambiguous, that indicates the octave the pitch is in. Pitch (music)_sentence_43

Just-noticeable difference Pitch (music)_section_3

The just-noticeable difference (jnd) (the threshold at which a change is perceived) depends on the tone's frequency content. Pitch (music)_sentence_44

Below 500 Hz, the jnd is about 3 Hz for sine waves, and 1 Hz for complex tones; above 1000 Hz, the jnd for sine waves is about 0.6% (about 10 cents). Pitch (music)_sentence_45

The jnd is typically tested by playing two tones in quick succession with the listener asked if there was a difference in their pitches. Pitch (music)_sentence_46

The jnd becomes smaller if the two tones are played simultaneously as the listener is then able to discern beat frequencies. Pitch (music)_sentence_47

The total number of perceptible pitch steps in the range of human hearing is about 1,400; the total number of notes in the equal-tempered scale, from 16 to 16,000 Hz, is 120. Pitch (music)_sentence_48

Aural illusions Pitch (music)_section_4

The relative perception of pitch can be fooled, resulting in aural illusions. Pitch (music)_sentence_49

There are several of these, such as the tritone paradox, but most notably the Shepard scale, where a continuous or discrete sequence of specially formed tones can be made to sound as if the sequence continues ascending or descending forever. Pitch (music)_sentence_50

Definite and indefinite pitch Pitch (music)_section_5

Not all musical instruments make notes with a clear pitch. Pitch (music)_sentence_51

The unpitched percussion instrument (a class of percussion instrument) does not produce particular pitches. Pitch (music)_sentence_52

A sound or note of definite pitch is one where a listener can possibly (or relatively easily) discern the pitch. Pitch (music)_sentence_53

Sounds with definite pitch have harmonic frequency spectra or close to harmonic spectra. Pitch (music)_sentence_54

A sound generated on any instrument produces many modes of vibration that occur simultaneously. Pitch (music)_sentence_55

A listener hears numerous frequencies at once. Pitch (music)_sentence_56

The vibration with the lowest frequency is called the fundamental frequency; the other frequencies are overtones. Pitch (music)_sentence_57

Harmonics are an important class of overtones with frequencies that are integer multiples of the fundamental. Pitch (music)_sentence_58

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. Pitch (music)_sentence_59

A sound or note of indefinite pitch is one that a listener finds impossible or relatively difficult to identify as to pitch. Pitch (music)_sentence_60

Sounds with indefinite pitch do not have harmonic spectra or have altered harmonic spectra—a characteristic known as inharmonicity. Pitch (music)_sentence_61

It is still possible for two sounds of indefinite pitch to clearly be higher or lower than one another. Pitch (music)_sentence_62

For instance, a snare drum sounds higher pitched than a bass drum though both have indefinite pitch, because its sound contains higher frequencies. Pitch (music)_sentence_63

In other words, it is possible and often easy to roughly discern the relative pitches of two sounds of indefinite pitch, but sounds of indefinite pitch do not neatly correspond to any specific pitch. Pitch (music)_sentence_64

A special type of pitch often occurs in free nature when sound reaches the ear of an observer directly from the source, and also after reflecting off a sound-reflecting surface. Pitch (music)_sentence_65

This phenomenon is called repetition pitch, because the addition of a true repetition of the original sound to itself is the basic prerequisite. Pitch (music)_sentence_66

Pitch standards and standard pitch Pitch (music)_section_6

Main article: Concert pitch Pitch (music)_sentence_67

A pitch standard (also concert pitch) is the conventional pitch reference a group of musical instruments are tuned to for a performance. Pitch (music)_sentence_68

Concert pitch may vary from ensemble to ensemble, and has varied widely over musical history. Pitch (music)_sentence_69

Standard pitch is a more widely accepted convention. Pitch (music)_sentence_70

The A above middle C is usually set at 440 Hz (often written as "A = 440 Hz" or sometimes "A440"), although other frequencies, such as 442 Hz, are also often used as variants. Pitch (music)_sentence_71

Another standard pitch, the so-called Baroque pitch, has been set in the 20th century as A = 415 Hz—approximately an equal-tempered semitone lower than A440 to facilitate transposition. Pitch (music)_sentence_72

Transposing instruments have their origin in the variety of pitch standards. Pitch (music)_sentence_73

In modern times, they conventionally have their parts transposed into different keys from voices and other instruments (and even from each other). Pitch (music)_sentence_74

As a result, musicians need a way to refer to a particular pitch in an unambiguous manner when talking to each other. Pitch (music)_sentence_75

For example, the most common type of clarinet or trumpet, when playing a note written in their part as C, sounds a pitch that is called B♭ on a non-transposing instrument like a violin (which indicates that at one time these wind instruments played at a standard pitch a tone lower than violin pitch). Pitch (music)_sentence_76

To refer to that pitch unambiguously, a musician calls it concert B♭, meaning, "...the pitch that someone playing a non-transposing instrument like a violin calls B♭." Pitch (music)_sentence_77

Labeling pitches Pitch (music)_section_7

Scales Pitch (music)_section_8

The relative pitches of individual notes in a scale may be determined by one of a number of tuning systems. Pitch (music)_sentence_78

In the west, the twelve-note chromatic scale is the most common method of organization, with equal temperament now the most widely used method of tuning that scale. Pitch (music)_sentence_79

In it, the pitch ratio between any two successive notes of the scale is exactly the twelfth root of two (or about 1.05946). Pitch (music)_sentence_80

In well-tempered systems (as used in the time of Johann Sebastian Bach, for example), different methods of musical tuning were used. Pitch (music)_sentence_81

In almost all of these systems interval of the octave doubles the frequency of a note; for example, an octave above A440 is 880 Hz. Pitch (music)_sentence_82

If however the first overtone is sharp due to inharmonicity, as in the extremes of the piano, tuners resort to octave stretching. Pitch (music)_sentence_83

Other musical meanings of pitch Pitch (music)_section_9

In atonal, twelve tone, or musical set theory a "pitch" is a specific frequency while a pitch class is all the octaves of a frequency. Pitch (music)_sentence_84

In many analytic discussions of atonal and post-tonal music, pitches are named with integers because of octave and enharmonic equivalency (for example, in a serial system, C♯ and D♭ are considered the same pitch, while C4 and C5 are functionally the same, one octave apart). Pitch (music)_sentence_85

Discrete pitches, rather than continuously variable pitches, are virtually universal, with exceptions including "tumbling strains" and "indeterminate-pitch chants". Pitch (music)_sentence_86

Gliding pitches are used in most cultures, but are related to the discrete pitches they reference or embellish. Pitch (music)_sentence_87

See also Pitch (music)_section_10

Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Pitch (music).