Chirality
A scale is called chiral if reversing the order of the steps results in a different scale. The two scales form a chiral pair and are right/left-handed. Handedness is determined by writing both scales in their canonical mode and then comparing the size of both. The smallest example of a chiral pair in an EDO is 321/312, with the former being right-handed and the latter being left-handed.
Scales for which this property does not hold are called achiral. For example, the diatonic scale is achiral because 2221221 reverses to 1221222, which is identical to the original scale up to cyclical permutation.
Properties:
- Chiral scales can only exist in EDO's larger than 5-EDO
- Chiral scales are at least max-variety 3 (they cannot be MOS or DE)
- Chiral scales have at least 3 notes
- Chiral scales have a density of 1 (see table below)
| EDO | Number of
Chiral Scales |
Percentage of
Chiral Scales |
Corresponding Ratio |
| 1 | 0 | 0.0% | 0/1 |
| 2 | 0 | 0.0% | 0/1 |
| 3 | 0 | 0.0% | 0/1 |
| 4 | 0 | 0.0% | 0/1 |
| 5 | 0 | 0.0% | 0/1 |
| 6 | 2 | 22.2% | 2/9 |
| 7 | 4 | 22.2% | 2/9 |
| 8 | 12 | 40.0% | 2/5 |
| 9 | 28 | 50.0% | 1/2 |
| 10 | 60 | 60.6% | 20/33 |
| 11 | 124 | 66.7% | 2/3 |
| 12 | 254 | 75.8% | 254/335 |
| 13 | 504 | 80.0% | 4/5 |
| 14 | 986 | 84.9% | 986/1161 |
| 15 | 1936 | 88.7% | 968/1091 |
| 16 | 3720 | 91.2% | 31/34 |
| 17 | 7200 | 93.4% | 240/257 |
| 18 | 13804 | 95.0% | 493/519 |
| 19 | 26572 | 96.3% | 26/27 |
| 20 | 50892 | 97.2% | 16964/17459 |