| • Science | • People | • Locations | • Timeline |
| Contents | ||
It must be noted that pitch is something we perceive, whereas frequency is the physical measurement of vibration. We can state that the note A above middle C played on any instrument gives the same pitch perception as the pure tone at 440Hz, which has exactly defined frequency. A slight change in frequency need not mean a change in pitch but a change in pitch implies a change in frequency. In fact, the just noticeable difference, the threshold at which a change in pitch is perceived, is about five cents, but varies over the range of hearing and is more precise when the two pitches are played simultaneously. Like other human stimuli, the perception of pitch also can be explained by the Weber-Fechner Law.
Pitches may be described in various ways, including high or low, as discrete or indiscrete, gliding or portamento, and as determinate or indeterminate. Pitch is often measured by frequency or wavelength, but is most often discussed either through notation and the accompanying letter labels (C#). Musically the frequency of specific pitches is not as important as their relationships to other frequencies - the difference between two pitches can be expressed by a ratio or measured in cents. People with a sense of these relationships are said to have relative pitchThe term relative pitch may denote: the distance of a musical note from a set point of reference, e. three octaves above middle C" a musician's ability to identify the intervals between given tones, regardless of their relation to concert pitch (A 440Hz) while people who have a sense of the actual frequencies independent of other pitches are said to have absolute pitchAbsolute pitch is either the exact pitch of a note described by its number of vibrations per second, or the ability, commonly referred to as perfect pitch to identify a note by name without the benefit of a reference note. The ability to attach labels to, less accurately called perfect pitch.
The relative pitches of individual notes in a scaleIn music, a scale is an ascending or descending series of notes or pitches, as opposed to a series of intervals, which is a musical mode. Each note in a scale is referred to as a scale degree''. Though the scales from musical traditions around the world a may be determined by one of a number of tuningThis page is about musical 'systems' of tuning, for the musical 'process' of tuning see tuning. Musical tuning is the system used to define which tones, or pitches, to use when playing music. In other words, it is the choice of level and spacing of freque systems. In the west, the twelve-note chromatic scaleThe chromatic scale is a musical scale that contains all twelve pitches of the Western tempered scale. All of the other scales in traditional Western music are currently subsets of this scale. Each pitch is separated from its upper and lower neighbors by is the most common method of organization, with equal temperamentEqual temperament is a scheme of musical tuning in which the octave is divided into a series of equal steps (equal frequency ratios). The best known example of such a system is twelve t one e qual t emperament sometimes abbreviated to 12-TET which is nowa now the most widely used method of tuning that scale. In it, the pitch ratio between any two successive notes of the scale is exactly the twelfth root of two. In well-tempered systems (as used in the time of Johann Sebastian Bach, for example), different methods of musical tuning were used. Almost all of these systems have one interval in common, the octave, where the pitch of one note is double the frequency of another. For example, if the A above middle C is 440 Hz, the A an octave above that will be .
Like other senses, the relative perception of pitch can be fooled, resulting in " audio illusions". 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 like this sequence continues ascending forever, when this in fact is a clever audio illusion.
In atonal, twelve tone, or set theory a "pitch" is a specific frequency while a pitch class is all the octaves of a frequency. Pitches are named with integers because of octave and enharmonic equivalency (for example, C# and Db are the same pitch while C4 and C5 are functionally the same).
Discrete pitches, rather than continuously variable pitches, are virtually universal, with exceptions including "tumbling strains" (Sachs & Kunst, 1962) and "indeterminate-pitch chants" (Malm, 1967). Gliding pitches are used in most cultures, but are related to the discrete pitches they reference or embellish. (Burns, 1999)