Rhythms, Polymeter and Polyrhythm

                Rhythms, Polymeter and Polyrhythm

I have a lot of college work to catch up on, as well as stay ahead of new topics, such as today’s Poly Rhythm and Poly Meter class, and as I am REALLY weak in this area, as far as a defined technical understanding of the basic concepts and terminology of these timing based topics, I thought a Post would help me get it clearer in my head. Rhythm for example – you know what it is, but try to define it!

At this stage, this WikiP comment sums things up for this topic.

“The main distinction is between Polyrhythms and Polymeters. The two are often confused.

http://en.wikipedia.org/wiki/Polyrhythm

“Polyrhythm is the simultaneous use of two or more conflicting rhythms that are not readily perceived as deriving from one another, or as simple manifestations of the same meter.”

Polyrhythm is sometimes referred to as “measure preserving polymeter,”. The beat varies and the measure stays constant. For example, in a 4:3 polyrhythm, one part plays 4/4 while the other plays 3/4, but the 3/4 beats are stretched so that three beats of 3/4 are played in the same time as four beats of 4/4.”

“Polymeter is sometimes referred to as “tactus-preserving polymeter.” The measure size differs, the beat is the same. Since the beat is the same, the various meters eventually agree. (Four measures of 7/4 = seven measures of 4/4).”

NOPE – Clear as mud still! The Polyrhythm is defined in terms of Polymeter above! Big help.

OK – this graphic sums a Polyrhythm up better:

It is where the “conflicting” timings above of triplets and duplets fit exactly into the same bar length.

http://en.wikipedia.org/wiki/Polymeter

“… the organization of music into regularly recurring measures or bars of stressed and unstressed “beats”, indicated in Western music notationby a time signature and bar-lines.”

Basically, in a Polymeter, the bar lengths for one timing like ¾, and another like 4/4 are NOT preserved. They are different length bars of time, but may coincide periodically over a larger time frame.

OK, I’m going to have to go back to real basics on this one, to define the simplest case of Rhythm, first, before simultaneous variations of these can be played together:

http://en.wikipedia.org/wiki/Rhythmic_unit#Unit_and_gesture

“Rhythm (from Greek ??????—rhythmos, “any regular recurring
motion, symmetry[1]) generally means a “movement marked by the regulated succession of strong and weak elements, or of opposite or different conditions.”

Rhythm is the variation of the length and accentuation of a series of sounds or other events.”

In other words, a repetitive cycle marked by an “accent” at a defined period (usually the start) which in the simplest Western music case, is taken as a bar of four equal measures of beats (notes) playing for four equal periods of time. The 1-2-3-4 time signature of Dance, say.

There can be time cycles of different length and duration, after which, multiples of smaller periods fit equally into larger ones, effectively ending an infinite growth in beats per bar, and so bar length – regardless of tempo (the rate per minute of the amount of beats played in real time).

Larger time signatures can then be viewed as groups of smaller ones strung together dependent on where the accent falls. For example, if you count 5/4 time as 5 repeating beats – 1.2.3.4.5; 1.2.3.4.5… etc. and emphasise the first beat each time, you will get a stable loop, like the guitar riff on the track Kid Gloves by Rush:

https://www.youtube.com/watch?v=7qJmYCY7q1U

But this time signature can also be thought of as 2 smaller groups being counted as 1,2,3-1,2; 1,2,3;1,2…the same time signature, but giving different rhythms – it could be accented on the 1 and 3 only – 1,2,3,1,2, or on the one and two – giving different rhythm to same 5/4 signature.

FiveFour.mp3

ThreeTwo.mp3

TwoThree.mp3

The default Sequencer length comprises 1 bar of 4 beats. Each beat is divided into 4 x 1/16 notes – a total bar length of 16 x 1/16 notes – obviously…

In the Sequencer window, the time signature was changed to 5/4 by dragging the top left LCD window number up from — to 5, so changing the default total length from 4 x 4 beats, to 5 x 4 beats = 20/16 notes.

This is a mathematical way to work out what total bars are required for multiple different time signatures to synchronise periodically, so for a 4/4 kick drum beat with 3/4 hi hats, the loop sync would happen at every 3 x 4 = 12 beats, so the common time signature for both is 12 x 1/16 notes provided the ¾ time quarter notes are lengthened!

The key to realising how this works as a Polyrhythm is when you look at each set of ¾ and 4/4 time quarter notes in the Piano Roll, as you see that the ¾ time notes are longer in duration than the 4/4. They have to be “stretched” to fit and become 4 lots of triplet quarter notes.

44sixteenths.jpg

Looking at this, it could be simplified to a 12 notes in 1 beat loop for just these 3 Channels, as the kick (1)and snare (7) make a 1-2 count, with the hi hats on 1, 5 and 9 as a 1-2-3 count in the same time frame. Having more bars now though allows for adding more complex rhythms later.

34Poly.jpg

4kicksn3hat.mp3

You can count 1,2 -1,2… on the kick and snare, or concentrate on the 3/4 hi hats. This sort of time signature mixing can become complex and disorientating or hypnotic, and you can get up to complex mischief with just mixing 4/4 and 3/4 time with multiple instruments and accents on different beats alone.

The 3/4 hi hats could have the accent changed to the 3rd beat adding the clap to give a different feel:

4kicksn3hatClap.mp3

Adding BooBass, we could accentuate a Waltz in 3/4 time with a bass line, so changing the Snap to 1/3 beat in its Piano Roll:

4kicksn3hatClapBass.mp3

Here I add a Piano chord on notes 5 and 11 of 1 bar to accent a 5 count – still with Snap to 1/3 beat:

511Piano.mp3

And now I got so carried away with this fun – I added more percussion instruments and a Sytrus Acid track as these first few Sytrus presets tend to arpeggiate in time and delay FX with the BPM from a single note trigger:

I love it! Poly Percussion Mayhem…This simple study exercise becomes another handy tool in the creative tool box, as you don’t know where experimentation like this will take you. I would never have imagined writing a piece like this from my current music knowledge thought train.

What I like is there is plenty to focus on at different levels without it appearing too complex as a basic tune on the surface.

The consecutive 4 x 1/16 note Cowbell worked well as a ringing telephone rhythm through it which is odd but works! This principle is used as an effect now for really increasingly fast snare rolls that become a “machine gun” type of blur in some tracks like Zircon uses sometime, with a pitch shift or Phaser etc. also.

PolyPercSytrus.mp3

Actually, I just cloned the Cowbell Channel, turned them off, and used a TiteyRide bell sound instead so it is more like a phone:

PolyPercPhone.mp3

I prefer the blocks overall though, as percussion.

Try it yourself and see what wackiness evolves…

So you can see how complex this can become, here is the video we were shown in class:

 

ogene udu 1

http://www.youtube.com/watch?v=RVwJTXz7j98