Period: Difference between revisions
Improve lead section, add "Scale types" section (not sure about the title, good enough for now), enclose last part into an "Examples" section, categories |
Move non-periodic scales at the bottom of the page, rephrase its definition to lessen the impression that the term is common. |
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The '''period''' (or '''interval of repetition''') of a [[scale]] is the [[interval]] at which the scale's [[step pattern]] eventually repeats, if it does at all. | The '''period''' (or '''interval of repetition''') of a [[scale]] is the [[interval]] at which the scale's [[step pattern]] eventually repeats, if it does at all. In practice, the period often corresponds to the [[equave]] (interval of equivalence) or to a fraction of the equave. | ||
A ''[[periodic scale]]'' is a scale whose step pattern always repeats after a certain number of steps. The [[diatonic scale]] is an example of periodic scale. | |||
An ''aperiodic scale'' is a scale whose step pattern never repeats. The [[harmonic series]] is an example of aperiodic scale. | |||
In [[regular temperament theory]], the period of a scale always coincides with one of its generators. | In [[regular temperament theory]], the period of a scale always coincides with one of its generators. | ||
== Examples == | == Examples == | ||
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The same definition applies for a [[rank]]-2 temperament, when the temperament is seen as generating a mos. Every interval of a rank-2 temperament is a sum of some number of the period and some number of the generator of the temperament. | The same definition applies for a [[rank]]-2 temperament, when the temperament is seen as generating a mos. Every interval of a rank-2 temperament is a sum of some number of the period and some number of the generator of the temperament. | ||
== Special cases == | |||
A scale whose step pattern does not systematically repeat, but that may have small repeating segments in its step pattern, may be called a ''non-periodic scale''. This type of scale is less common, but technically includes any scale with a finite number of notes and which is not expected to repeat at all, such as the sequence of DTMF tones. Aperiodic scales are a subset of non-periodic scales. | |||
[[Category:Scale]] | [[Category:Scale]] | ||
[[Category:Generator]] | [[Category:Generator]] | ||
[[Category:Terms]] | [[Category:Terms]] | ||