A continuation of the discussion from: Dealing with Irregular Beats in the Music of Chip MichaelModern music moves fast, often too fast for the human to accurately count. The reason for this is we (composers) have taken subdivision to a new level. We are breaking down the events that happen in a given moment, subdivided it and attached events to each of those divisions. Brian Ferneyhough, Michael Finnissy and other composers of the "New Complexity" give musicians an inordinate amount of information to take at each moment. In order to accomplish the actual "beat" of their music is rather slow, eighth = 56 is fairly common.
My music takes a page from this book. However, rather than try and cram a lot of information into a single note space, I use the a variable beat with a consistent under pulse.
In the new piece for TwtrSymphony, The Hawk Goes Hunting (a working title) the opening page shifts between 9/8 and 13/8 meters. But don't count the measures in 9 or 13. Count them in two and three.
The first measure is divided into the strong beats (solid red lines), and the weak sub-beats (dotted pink line). The first beat has three eighth notes in the first half and two in the second, where the second beat has two eight notes in each sub-beat. The 13/8 bar is similarly divided, with the first beat sub-divided into three eight notes and two eight notes, and the other two beats sub-divided into two eighth notes in each half of the beat. Counting this (or conducting this), I would expect to see, "One, and, Two, and." Then "One, and, Two, and, Three, and." If the conductor were to try and wave his or her arms about counting each eighth note, their arms would fall off mid way through the piece and the musicians would have no idea where they are in the music. However, but sub-dividing the "actual" beats of the music into a constant steady pulse, while the beat changes length/duration, the pulse is ever present.
The key to counting a variable beat is knowing how it is sub-divided. This does put the expectation on the player to know how the beat sub-divisions shift measure to measure, particularly since 13/8 may be divided into three beats and sometimes four. However, the flow of the music has a more syncopated feel, which is something composer since way back to Machaut (14th century) have been incorporating into their music.