27/26
| Interval information |
reduced
[sound info]
In 13-limit just intonation, 27/26, the small tridecimal third tone, appears as the interval between the Pythagorean major sixth of 27/16 and the thirteenth harmonic of 13/8. It measures about 65.3¢. It is close in size to another 13-limit microtone – 26/25. These intervals differ by the superparticular ratio 676/675, about 2.6¢, the island comma; tempering it out produces temperaments associated with The Archipelago.
27/26 is significant in Helmholtz-Ellis notation as the tridecimal formal comma which translates a Pythagorean interval to a nearby tridecimal interval, analogous to 64/63 and 33/32 for septimal and undecimal, respectively. However, in Functional Just System, that role is taken by 1053/1024.