Syncopation, polyrhythm, and groove

There are three basic types of tension expressed in the relation between rhythm and meter: syncopation, polyrhythm, and groove.

Syncopation

Syncopation challenges our perception of meter. In other words, meter tells us where things are most likely to occur; syncopation subverts those expectations.

Generally, we expect rhythmic emphasis to occur on the downbeat (otherwise known as strong beats), as opposed to upbeats, or weak beats.

Here’s what no syncopation looks like:

We can syncopate this by simply removing beat 3. This emphasizes the weak part of the 2nd beat.

This example is more syncopated; all weak beats are emphasized, resulting in more tension. 

There’s a lot more to say about syncopation, but I’ll save that for a later post. For now, let’s move on to polyrhythm.

Polyrhythm

Sometimes meter is only weakly expressed; sometimes it’s not expressed at all. The rhythm in question may simply not communicate a meter, in which case the musicians rely on the listener to be able to predict the metrical framework.

Cross-rhythm is an example of this. Cross-rhythm occurs when a rhythmic pattern suggests more than one meter. An example is 3 against 4 – three equally spaced beats played against four equally spaced beats.

Is this in 3/4 or 4/4? Depending on how you listen, it can be one or the other. The ambiguity created by this phenomenon can create a lot of tension; and adding more layers with different meters adds more tension.

Metric displacement

Metric displacement occurs when a rhythmic motif starts  in a particular location…

and is then shifted to start in a different location.

This causes new relationships between layers. They interlock in new ways, and create different levels of complexity.

A simple example would be to imagine the first rhythm played in two separate parts… 

and then the first rhythm superimposed on the displaced rhythm.

  

Again, there’s lots more to say, but that will come later.

Groove

Groove can be as simple as a drum kit repeating a 2-bar pattern, or the complex interplay of a rhythm section. It involves some degree of syncopation, along with cross-rhythm and metric displacement; it is continuously repeated, and it makes you want to move.

In the context of continuous repetition, then, the violation of expectation (tension) found in syncopation and polyrhythm become pleasurable. This is good news, but makes me wonder how long a rhythmic unit can be repeated before it’s no longer pleasurable. In other words, when does it become boring?