Period: Difference between revisions
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This isn't limited to mos scales |
Improve lead section, add "Scale types" section (not sure about the title, good enough for now), enclose last part into an "Examples" section, categories |
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The '''period''' | 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. | |||
In [[regular temperament theory]], the period of a scale always coincides with one of its generators. | |||
== Scale types == | |||
* 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. | |||
* A ''non-periodic scale'' is a scale whose step pattern does not systematically repeat, but that may have small repeating segments in its step pattern. 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 {{w|DTMF}} tones. | |||
* An ''aperiodic scale'' is a scale whose step pattern never repeats. The [[harmonic series]] is an example of aperiodic scale. | |||
== Examples == | |||
In [[mos scale]]s, the period is one of the two defining intervals, the other being the [[generator]]. For example: | In [[mos scale]]s, the period is one of the two defining intervals, the other being the [[generator]]. For example: | ||
* The diatonic scale (LLsLLLs) has period equal to the octave. | * The diatonic scale (LLsLLLs) has period equal to the octave. | ||
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[[Category:Scale]] | [[Category:Scale]] | ||
[[Category: | [[Category:Generator]] | ||
[[Category:Terms]] | [[Category:Terms]] | ||
Revision as of 06:16, 23 February 2025
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.
In regular temperament theory, the period of a scale always coincides with one of its generators.
Scale types
- 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.
- A non-periodic scale is a scale whose step pattern does not systematically repeat, but that may have small repeating segments in its step pattern. 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.
- An aperiodic scale is a scale whose step pattern never repeats. The harmonic series is an example of aperiodic scale.
Examples
In mos scales, the period is one of the two defining intervals, the other being the generator. For example:
- The diatonic scale (LLsLLLs) has period equal to the octave.
- The diminished scale (sLsLsLsL) has period 1\4, since the mos pattern sL repeats at every 300 cents.
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.