Frameshift comma
The frameshift comma is an unnoticeable 11-limit comma- specifically of the 2.3.11 subgroup- with a complicated ratio of 22876792454961/22866405883904, and a size of roughly 0.79 cents. It is the interval separating the Rastma from the Pythrabian comma, as well as the amount by which an octave-reduced stack of three 11/8 intervals falls short of a stack of four apotomes. Since both the Rastmic and Pythrabian temperaments are ways of conceptualizing how the 11-prime relates to the 3-prime within the 2.3.11 subgroup, that means that these two distinct frameworks for viewing the 11-prime relative to the 3-prime become linked when 22876792454961/22866405883904 is tempered out- hence the name "frameshift" comma. Naturally, tempering out this comma results in some form of Frameshift microtemperament.
| Interval information |
Frameshift cadence
The name of the frameshift comma is even more appropriate in light of the fact that when one tempers out this comma, one can move stepwise to 11/8 though a series of four motions by the apotome and one motion by 128/121- all rather typical-sounding semitone-based motions- with this gesture forming the basis of what has since been dubbed the frameshift cadence- a cadence which shifts a listener's perception of pitch relations such that a modulation to 11/8 sounds in tune.
