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Scale 37: "Akha 3 Tone"

Scale 37: Akha 3 Tone, Ian Ring Music Theory

Bracelet Diagram

The bracelet shows tones that are in this scale, starting from the top (12 o'clock), going clockwise in ascending semitones. The "i" icon marks imperfect tones that do not have a tone a fifth above. Dotted lines indicate axes of symmetry.

Tonnetz Diagram

Tonnetz diagrams are popular in Neo-Riemannian theory. Notes are arranged in a lattice where perfect 5th intervals are from left to right, major third are northeast, and major 6th intervals are northwest. Other directions are inverse of their opposite. This diagram helps to visualize common triads (they're triangles) and circle-of-fifth relationships (horizontal lines).

Common Names

Southeast Asia
Akha 3 Tone
Karen 3 Tone Type 1
Lahuzu 3 Tone Type 2
Western Modern
Minor Seventh Trichord



Cardinality is the count of how many pitches are in the scale.

3 (tritonic)

Pitch Class Set

The tones in this scale, expressed as numbers from 0 to 11


Forte Number

A code assigned by theorist Allen Forte, for this pitch class set and all of its transpositional (rotation) and inversional (reflection) transformations.


Rotational Symmetry

Some scales have rotational symmetry, sometimes known as "limited transposition". If there are any rotational symmetries, these are the intervals of periodicity.


Reflection Axes

If a scale has an axis of reflective symmetry, then it can transform into itself by inversion. It also implies that the scale has Ridge Tones. Notably an axis of reflection can occur directly on a tone or half way between two tones.



A palindromic scale has the same pattern of intervals both ascending and descending.



A chiral scale can not be transformed into its inverse by rotation. If a scale is chiral, then it has an enantiomorph.

enantiomorph: 1153


A hemitone is two tones separated by a semitone interval. Hemitonia describes how many such hemitones exist.

0 (anhemitonic)


A cohemitone is an instance of two adjacent hemitones. Cohemitonia describes how many such cohemitones exist.

0 (ancohemitonic)


An imperfection is a tone which does not have a perfect fifth above it in the scale. This value is the quantity of imperfections in this scale.



Modes are the rotational transformations of this scale. This number does not include the scale itself, so the number is usually one less than its cardinality; unless there are rotational symmetries then there are even fewer modes.


Prime Form

Describes if this scale is in prime form, using the Starr/Rahn algorithm.



Indicates if the scale can be constructed using a generator, and an origin.


Deep Scale

A deep scale is one where the interval vector has 6 different digits, an indicator of maximum hierarchization.


Interval Structure

Defines the scale as the sequence of intervals between one tone and the next.

[2, 3, 7]

Interval Vector

Describes the intervallic content of the scale, read from left to right as the number of occurences of each interval size from semitone, up to six semitones.

<0, 1, 1, 0, 1, 0>

Proportional Saturation Vector

First described by Michael Buchler (2001), this is a vector showing the prominence of intervals relative to the maximum and minimum possible for the scale's cardinality. A saturation of 0 means the interval is present minimally, a saturation of 1 means it is the maximum possible.

<0, 0.5, 0.5, 0, 0.5, 0>

Interval Spectrum

The same as the Interval Vector, but expressed in a syntax used by Howard Hanson.


Distribution Spectra

Describes the specific interval sizes that exist for each generic interval size. Each generic <g> has a spectrum {n,...}. The Spectrum Width is the difference between the highest and lowest values in each spectrum.

<1> = {2,3,7}
<2> = {5,9,10}

Spectra Variation

Determined by the Distribution Spectra; this is the sum of all spectrum widths divided by the scale cardinality.


Maximally Even

A scale is maximally even if the tones are optimally spaced apart from each other.


Maximal Area Set

A scale is a maximal area set if a polygon described by vertices dodecimetrically placed around a circle produces the maximal interior area for scales of the same cardinality. All maximally even sets have maximal area, but not all maximal area sets are maximally even.


Interior Area

Area of the polygon described by vertices placed for each tone of the scale dodecimetrically around a unit circle, ie a circle with radius of 1.


Polygon Perimeter

Perimeter of the polygon described by vertices placed for each tone of the scale dodecimetrically around a unit circle.


Myhill Property

A scale has Myhill Property if the Distribution Spectra have exactly two specific intervals for every generic interval.



A scale is balanced if the distribution of its tones would satisfy the "centrifuge problem", ie are placed such that it would balance on its centre point.


Ridge Tones

Ridge Tones are those that appear in all transpositions of a scale upon the members of that scale. Ridge Tones correspond directly with axes of reflective symmetry.



Also known as Rothenberg Propriety, named after its inventor. Propriety describes whether every specific interval is uniquely mapped to a generic interval. A scale is either "Proper", "Strictly Proper", or "Improper".


Heteromorphic Profile

Defined by Norman Carey (2002), the heteromorphic profile is an ordered triple of (c, a, d) where c is the number of contradictions, a is the number of ambiguities, and d is the number of differences. When c is zero, the scale is Proper. When a is also zero, the scale is Strictly Proper.

(1, 0, 6)

Coherence Quotient

The Coherence Quotient is a score between 0 and 1, indicating the proportion of coherence failures (ambiguity or contradiction) in the scale, against the maximum possible for a cardinality. A high coherence quotient indicates a less complex scale, whereas a quotient of 0 indicates a maximally complex scale.


Sameness Quotient

The Sameness Quotient is a score between 0 and 1, indicating the proportion of differences in the heteromorphic profile, against the maximum possible for a cardinality. A higher quotient indicates a less complex scale, whereas a quotient of 0 indicates a scale with maximum complexity.



This scale has no generator.

Common Triads

There are no common triads (major, minor, augmented and diminished) that can be formed using notes in this scale.


Modes are the rotational transformation of this scale. Scale 37 can be rotated to make 2 other scales. The 1st mode is itself.

2nd mode:
Scale 1033
Scale 1033: Ute Tritonic, Ian Ring Music TheoryUte Tritonic
3rd mode:
Scale 641
Scale 641: Lahuzu 3 Tone Type 1, Ian Ring Music TheoryLahuzu 3 Tone Type 1


This is the prime form of this scale.


The tritonic modal family [37, 1033, 641] (Forte: 3-7) is the complement of the enneatonic modal family [1471, 1789, 2027, 2783, 3061, 3439, 3767, 3931, 4013] (Forte: 9-7)


The inverse of a scale is a reflection using the root as its axis. The inverse of 37 is 1153

Scale 1153Scale 1153: CHOian, Ian Ring Music TheoryCHOian


Only scales that are chiral will have an enantiomorph. Scale 37 is chiral, and its enantiomorph is scale 1153

Scale 1153Scale 1153: CHOian, Ian Ring Music TheoryCHOian


In the abbreviation, the subscript number after "T" is the number of semitones of tranposition, "M" means the pitch class is multiplied by 5, and "I" means the result is inverted. Operation is an identical way to express the same thing; the syntax is <a,b> where each tone of the set x is transformed by the equation y = ax + b

Abbrev Operation Result Abbrev Operation Result
T0 <1,0> 37       T0I <11,0> 1153
T1 <1,1> 74      T1I <11,1> 2306
T2 <1,2> 148      T2I <11,2> 517
T3 <1,3> 296      T3I <11,3> 1034
T4 <1,4> 592      T4I <11,4> 2068
T5 <1,5> 1184      T5I <11,5> 41
T6 <1,6> 2368      T6I <11,6> 82
T7 <1,7> 641      T7I <11,7> 164
T8 <1,8> 1282      T8I <11,8> 328
T9 <1,9> 2564      T9I <11,9> 656
T10 <1,10> 1033      T10I <11,10> 1312
T11 <1,11> 2066      T11I <11,11> 2624
Abbrev Operation Result Abbrev Operation Result
T0M <5,0> 1027      T0MI <7,0> 2053
T1M <5,1> 2054      T1MI <7,1> 11
T2M <5,2> 13      T2MI <7,2> 22
T3M <5,3> 26      T3MI <7,3> 44
T4M <5,4> 52      T4MI <7,4> 88
T5M <5,5> 104      T5MI <7,5> 176
T6M <5,6> 208      T6MI <7,6> 352
T7M <5,7> 416      T7MI <7,7> 704
T8M <5,8> 832      T8MI <7,8> 1408
T9M <5,9> 1664      T9MI <7,9> 2816
T10M <5,10> 3328      T10MI <7,10> 1537
T11M <5,11> 2561      T11MI <7,11> 3074

The transformations that map this set to itself are: T0

Nearby Scales:

These are other scales that are similar to this one, created by adding a tone, removing a tone, or moving one note up or down a semitone.

Scale 39Scale 39: AFUian, Ian Ring Music TheoryAFUian
Scale 33Scale 33: Honchoshi, Ian Ring Music TheoryHonchoshi
Scale 35Scale 35: Major Seventh Trichord, Ian Ring Music TheoryMajor Seventh Trichord
Scale 41Scale 41: Vietnamese Tritonic, Ian Ring Music TheoryVietnamese Tritonic
Scale 45Scale 45: APRian, Ian Ring Music TheoryAPRian
Scale 53Scale 53: ABSian, Ian Ring Music TheoryABSian
Scale 5Scale 5: Vietnamese Ditonic, Ian Ring Music TheoryVietnamese Ditonic
Scale 21Scale 21: Wholetone Trichord, Ian Ring Music TheoryWholetone Trichord
Scale 69Scale 69: DEZian, Ian Ring Music TheoryDEZian
Scale 101Scale 101: All-Interval Tetrachord 3, Ian Ring Music TheoryAll-Interval Tetrachord 3
Scale 165Scale 165: Genus Primum, Ian Ring Music TheoryGenus Primum
Scale 293Scale 293: Raga Haripriya, Ian Ring Music TheoryRaga Haripriya
Scale 549Scale 549: Lahuzu 4 Tone Type 4, Ian Ring Music TheoryLahuzu 4 Tone Type 4
Scale 1061Scale 1061: Karen 4 Tone Type 4, Ian Ring Music TheoryKaren 4 Tone Type 4
Scale 2085Scale 2085: MOGian, Ian Ring Music TheoryMOGian

This scale analysis was created by Ian Ring, Canadian Composer of works for Piano, and total music theory nerd. Scale notation generated by VexFlow and Lilypond, graph visualization by Graphviz, audio by TiMIDIty and FFMPEG. All other diagrams and visualizations are © Ian Ring. Some scale names used on this and other pages are ©2005 William Zeitler ( used with permission.

Pitch spelling algorithm employed here is adapted from a method by Uzay Bora, Baris Tekin Tezel, and Alper Vahaplar. (An algorithm for spelling the pitches of any musical scale) Contact authors Patent owner: Dokuz Eylül University, Used with Permission. Contact TTO

Tons of background resources contributed to the production of this summary; for a list of these peruse this Bibliography. Special thanks to Richard Repp for helping with technical accuracy, and George Howlett for assistance with the Carnatic ragas.