Pitch class: Difference between revisions

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A ''pitch class'' is a set (equivalence class) of all pitches that are a whole number of octaves (2/1) apart, e.g., the pitch class C consists of the Cs in all octaves. Thus the pitch class "C" is the set
{{Wikipedia|Pitch class}}
A '''pitch class''' is a set (equivalence class) of all pitches that are a whole number of [[octave]]s (2/1) apart, e.g., the pitch class C consists of the Cs in all octaves. Thus the pitch class "C" is the set


<math>{..., C_{-2}, C_{-1}, C_0, C_1, C_2 ...}</math>
<math>\left\lbrace \ldots, C_{-2}, C_{-1}, C_0, C_1, C_2, \ldots \right\rbrace</math>


In terms of frequencies expressed in hertz, assuming a base frequency for middle C of 262 Hz, this would be {... 65.5, 131, 262, 524, 1028 ...}. In terms of midi note numbers, we can write it as {... 36, 48, 60, 72, 84 ...}.
In terms of frequencies expressed in [[Hertz]], assuming a base frequency for middle C of 262&nbsp;Hz, this would be {…, 65.5, 131, 262, 524, 1028, …}. In terms of [[MIDI]] note numbers, we can write it as {…, 36, 48, 60, 72, 84, …}.


In a [[nonoctave]] xenharmonic system, an interval other than the octave might be used to define equivalence. For example, in [[Bohlen-Pierce]] tuning, all pitches separated by a whole number of tritaves (3/1) may be considered equivalent.
In a [[nonoctave]] xenharmonic system, an interval other than the octave might be used to define [[equivalence]]. For example, in [[Bohlen–Pierce]] tuning and other [[edt|equal divisions per tritave]], all pitches separated by a whole number of tritaves (3/1) may be considered equivalent.


=Links=
== See also ==
http://en.wikipedia.org/wiki/Pitch_class
* [[Interval class]]
* [[Octave equivalence]]
* [[Periodic scale]]


[[Category:pitch]]
[[Category:Scale]]
[[Category:theory]]
[[Category:tone]]