# Rhythm

## Contents

## Rhythmic modes

The music discussed here (labeled Jazz, Blues or Rock) is built on a fixed tempo even if it can sometimes be elastic with localized speedups or slowdowns. This tempo is defined by the pulses, the central flow of the piece. The interval between these pulses defines the beat, which will be noted mainly by a quarter note or a dotted quarter note in ternary contexts.

The beat divisions are fundamental and define the amount of possible rhythmic degrees for each beat. These divisions, repeated every beat, form a rhythmic grid or matrix that underlies the whole piece and gives it its rhythmic identity.

The fundamental divisions of the beats are the divisions by 2 and by 3, all the other divisions are only multiples of them. These fundamental divisions are called here rhythmic cells: binary for the division by 2, and ternary for the division by 3. We thus obtain binary rhythmic grids and ternary grids.

These grids will be called here rhythmic modes, by analogy with the melodic modes, because they constitute like the latter a amount of degrees available for the musical speech.

In addition to this flow of beat divisions, we often have more or less neighboring flows, slower and faster, producing a rhythmic variety, notably in improvisations. There is a whole stratification of flows: broader and defining longer durations, such as the strong degrees of the measure, the measures themselves, the chords cycles, the bar structures, etc. We also have the faster flows, beat divisions, sub-divisions and other neighboring flows. The broader flows define the structure of the rhythmic speech while the faster flows are used as local speedups and dynamization of the speech.

In summary, we have 3 types of flow:

- the central flow of the divisions which, polarized by the pulses, form the rhythmic mode,

- then the wider flows used mainly for rhythmic structures,

- and finally the faster flows used as local dynamizations..

## Modes dynamics

The pulses function as poles of attraction on the other degrees of the rhythmic mode, and are thus its strong degrees. In the case of a mode made up of several rhythmic cells, the strong degrees of these cells are the support points, thus the secondary strong degrees of the mode.

It follows a hierarchical and dynamic classification of the degrees of the mode in 3 main levels:

- the poles of attraction ( pulses), by definition strong, therefore very stable degrees,

- the secondary poles of attraction (for the modes with several cells), strong and stable degrees,

- the other degrees, attracted by the poles, unstable.

The more divisions the mode has, the more complex its hierarchy and its corresponding dynamics are. The binary rhythmic cells are dynamically quite simple with the weak antipode degree, also attracted by the 2 neighboring pulses (previous and following). Ternary rhythmic cells are more dynamically complex, with 2 weak degrees, each attracted by their neighboring pulse. Ternary modes are thus globally more unstable than binary modes.

The binary or ternary character of a mode is not only due to its cell type, but also to their number. The combination of these 2 aspects allows us to classify the rhythmic modes in 3 groups :

- the binary modes, division by 2, 4 and 8, that is to say respectively 1, 2 and 4 binary cells,

- the mixed modes, division by 6, that is to say 3 binary cells or 2 ternary cells,

- ternary modes, division by 3 and 9, i.e. 1 and 3 ternary cells respectively.

Similarities in the number or type of cells define neighboring rhythmic modes. This proximity is used to move from one mode to another, a process that can be called rhythmic modulation. The doubling or halving of the tempo is only a particular case of modulation.

## Ternary interpretation

The binary rhythmic cell is a simple cell with a weak antipode degree, i.e. at equal distance between the preceding and following strong degrees and therefore equally attracted by these 2 poles. We obtain an alternation, a sort of pendulum movement between the strong and weak degrees. This dynamic pattern characterizes the binary cell modes and their derived rhythms.

In the ternary cell, this alternation disappears because there are 2 weak degrees, each attracted by its closest strong degree. There is therefore no antipode degree and the dynamics of this cell is more complex.

Ternary interpretation consists, starting from a binary rhythmic cell, in moving slightly the antipode weak degree towards the following strong degree at a distance of 1/3 of a beat, thus creating an implicit division by 3. The delay of this previously antipode degree produces an impression of swaying, of characteristic jumping called swing. We still have the alternation of strong and weak degrees, but in a non-linear, non-equal way. This situation tends in some way towards the ternary cell where all degrees can be played.

Rhythmic cells ternary interpreted are built on an implicit division of beats by 3, but using only the degrees of the binary cell. However, this delay or shift can vary with tempo, smaller in fast tempos and larger in slow tempos. This results in a variable "swing rate", determining the round/angular, soft/tense, etc. qualities of the rhythms, chosen as needed.

Once the ternary process has been mastered on the binary rhythmic cell, it is easy to apply it to the 2 and 3 cell modes, and all their derived rhythms, of varying lengths.

## Rhythm practice

We have seen previously that the fundamental divisions are the divisions of beats by 2 and 3 (binary and ternary cells). The higher divisions of beats are constructed by multiplying the number of cells per beat (example: division by 4 = 2 binary cells, etc.).

Ignoring the pulses, we can consider any rhythm as a set of duration ratios between its degrees: double of..., half of..., triple of..., etc. In the same way that a melodic line can be transposed exactly and thus keep the pitch relationships between its notes, which makes it immediately recognizable, the same rhythm can be applied to different beat divisions, while keeping the same duration relationships. In some cases, the dynamics of the rhythm are practically unchanged despite the fact that the notations are sometimes very different.

The idea of the exercises proposed here is to take advantage of rhythmic similarities hidden by different notations for a progressive learning of more and more complex beat divisions.

One can use the knowledge of the fundamental divisions by 2 and 3, on rhythms of different lengths, and apply them in the higher beats divisions. The principle is simple: play a rhythm over a whole number of beats, and divide the flow of the pulses by 2, 3, or even 4, while continuing the same rhythm. A rhythm, previously spread out over several beats and well fixed by frequent pulses, after dividing the flow of pulses, makes a bigger bridge between more spaced pulses. The rhythmic set-up is more acrobatic, but the rhythm is unchanged and its strong degrees are still there as support points.

One can thus start from the rhythms of division by 2 to approach those of divisions by 4, 6 and 8 (rhythmic modes with binary cells), and from the rhythms of division by 3 to practice those of divisions by 6 and 9 (modes with ternary cells).