15/11
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| Ratio | 15/11 |
| Factorization | 3 × 5 × 11-1 |
| Monzo | [0 1 1 0 -1⟩ |
| Size in cents | 536.95077¢ |
| Names | undecimal augmented fourth, undecimal grave infra-augmented fourth |
| Color name | 1uy4, luyo 4th |
| FJS name | [math]\text{A4}^{5}_{11}[/math] |
| Special properties | reduced |
| Tenney height (log2 nd) | 7.36632 |
| Weil height (log2 max(n, d)) | 7.81378 |
| Wilson height (sopfr (nd)) | 19 |
| Harmonic entropy (Shannon, [math]\sqrt{nd}[/math]) |
~4.26195 bits |
[sound info] | |
| open this interval in xen-calc | |
The interval 15/11, known most frequently as undecimal augmented fourth, is the difference between the 11th and 15th partials of the harmonic series. It is 536.95 cents wide, exactly 45/44 larger than a perfect fourth, and almost exactly a sixth-tone sharper than a 12edo fourth. It is narrower than 11/8 by exactly 121/120, and is wider than 27/20 by exactly 100/99. Additionally, it is narrower than 243/176 by exactly 81/80, which lends to it being called the undecimal grave infra-augmented fourth. 15/11 can be called a superfourth, as it falls between the interval categories of perfect fourth and tritone. 4 steps of 9edo is an excellent approximation for 15/11.