4afdo: Difference between revisions

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Terminological development
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[[File:4ado scale.wav|thumb]]
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'''4afdo''' ([[AFDO|arithmetic division of the octave]]), or '''4odo''' ([[otonal division]] of the octave), divides the octave into four parts of 1/4 each. As a scale it may be known as [[Harmonic mode|mode 4 of the harmonic series]] or the [[Overtone scale #Over-n scales|Over-4]] scale. Because 4 is a power of 2, 4afdo corresponds to the 4th to 8th harmonics octave-reduced. The notes of 4afdo create a harmonic seventh chord.
'''4afdo''' ([[AFDO|arithmetic division of the octave]]), or '''4odo''' ([[otonal division]] of the octave), divides the octave into four parts of 1/4 each. As a scale it may be known as [[Harmonic mode|mode 4 of the harmonic series]] or the [[Overtone scale #Over-n scales|Over-4]] scale. Because 4 is a power of 2, 4afdo corresponds to the 4th to 8th harmonics octave-reduced. The notes of 4afdo create a [[4:5:6:7|harmonic seventh chord]].
 
The smallest [[EDO]]s that maintain 25% or lower relative error on all intervals of 4afdo are [[10edo]] and [[15edo]], though they are not very accurate. The next two EDOs, [[22edo]] and [[31edo]], are the smallest that approximate 4afdo with appreciable accuracy.


== Intervals ==
== Intervals ==
{| class="wikitable center-all"
{| class="wikitable center-all"
|-
! #
! #
! Cents
! Cents

Revision as of 12:02, 12 February 2025

← 3afdo 4afdo 5afdo →
Prime factorization 22
Fifth 6/4 (701.955c)

4afdo (arithmetic division of the octave), or 4odo (otonal division of the octave), divides the octave into four parts of 1/4 each. As a scale it may be known as mode 4 of the harmonic series or the Over-4 scale. Because 4 is a power of 2, 4afdo corresponds to the 4th to 8th harmonics octave-reduced. The notes of 4afdo create a harmonic seventh chord.

The smallest EDOs that maintain 25% or lower relative error on all intervals of 4afdo are 10edo and 15edo, though they are not very accurate. The next two EDOs, 22edo and 31edo, are the smallest that approximate 4afdo with appreciable accuracy.

Intervals

# Cents Ratio Decimal Interval name Audio
0 0 1/1 1.0000 perfect unison
1 386.3 5/4 1.2500 just major third
2 702.0 3/2 1.5000 just perfect fifth
3 968.8 7/4 1.7050 harmonic seventh
4 1200.0 2/1 2.0000 perfect octave