Improve Your Sense of Rhythm: Polyrhythms, Polymeter and Dotted Feels (Part 3)

A polyrhythm comes from dividing the beat evenly (for example into four sixteenths in 3/4) and then accenting in a different grouping (every three), so a second time feel appears while the original pulse stays intact; polymeter strings different bar lengths together, and the dotted feel groups a duple division in threes.

Video lesson by Jason Zac · Advanced · 27 min

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What this lesson covers

This is the final part of Jason Zac's three-part rhythm series at Nathaniel School of Music. It explains three ideas that sound advanced but turn up constantly in pop, film, rock and folk music: polyrhythm, polymeter and the dotted feel. It is shown on piano, but the ideas apply to singers, drummers, guitarists and any instrument. It suits students who are already comfortable with pulse, time signatures and subdividing the beat.

A quick recap of Parts 1 and 2

• Feel the pulse first and let your body react to it.
• Notice how the pulse cycles into a time signature.
• Divide the beat by 2, 3 or 4, and decide whether it feels straight or swung.
• Build patterns by dividing and then leaving some divisions out, as in the gallop. This is the idea of divide more, play less.

Polyrhythm: four born from three

Keep the left hand in 3/4, counting one, two, three. Now divide each beat into four sixteenths: one-e-and-a, two-e-and-a, three-e-and-a. That gives twelve sixteenths per bar.

In the right hand, accent every third sixteenth instead of every beat. Because you never land on the same subdivision (one, e, and, a) twice in a row, the accents fall in four evenly spaced places across the bar. The ear hears a feel of four, even though you are still thinking in three.

Use the LCM

The least common multiple of 3 and 4 is 12, so you need at least twelve units before the two patterns line up again. Count those twelve as sixteenths (1-e-and-a, 2-e-and-a, 3-e-and-a) rather than one to twelve, which is much easier to read.

Two over three

Divide the beat by two instead: one-and, two-and, three-and. You get six eighth notes in a 3/4 bar. Grouping them to suggest a two feel over the three-beat pulse gives a 3:2 polyrhythm. Three against four, by contrast, needs you to think in sixteenths.

Flipping into a triplet feel

Now start from 4/4 and let the left hand play triplets, counting one-and-a, two-and-a, three-and-a, four-and-a. Simply changing how you count changes how the music feels. Whatever you superimpose, the pulse is never lost.

Polymeter: combining time signatures

Polyrhythm layers two feels over the same span of time. Polymeter places different bar lengths one after another. Examples from the lesson:

• A phrase in 7 followed by a phrase in 9.
• 7 meeting 6, the kind of grouping found in progressive rock and heavy metal riffs.
• 7 plus 8, giving a 15-count cycle. Large numbers like 15 are easier to feel when broken into smaller groups.

Jason's Celtic-flavoured tune The Jellyfish turned out to be 7 + 8 + 7 + 9 = 31 counts, even though the band first assumed it was in 4/4. He did not plan it mathematically. The grouping came from years of listening to bands such as Dream Theater, Rush and Pink Floyd. Listening comes first and analysis comes after.

The dotted feel

A dot adds half the note's value. A dotted crotchet is 1.5 beats, or three quavers. A dotted minim is three beats. A dotted quaver is 0.75 of a beat, or three semiquavers.

In practice, the dotted feel means you divide by two or four but move in groups of three. Divide by four and accent every three sixteenths, like a rock guitar delay echoing in dotted time. Try a simple up-and-down left-hand bass: play it on the normal pulse, then on the dotted pulse, and notice how much more driving it feels. It is common in rock, EDM and Latin music.

Dotted notes alone never resolve in 4/4. Use a few dotted hits as accents and then resolve at the end of the phrase.

How to practise

1. Listen to five to ten songs a week with pen and paper, including instrumentals and songs in languages you don't know.
2. For each song, find the pulse, then the time signature, the division, straight or swing, and finally the accents and phrases.
3. Slowly play a three-beat left hand against right-hand accents every three sixteenths, counting aloud.
4. Clap or play short odd-metre cycles such as 7 + 9, keeping the counts steady.

Play tightly and patiently first. Emotion and expression follow.

Questions about this lesson

What is the difference between a polyrhythm and a polymeter?

A polyrhythm layers two different groupings over the same span of time, such as accents implying four over a 3/4 bar. A polymeter strings together sections of different lengths, such as a bar of 7 followed by a bar of 9.

How do I play 4 over 3 on the piano?

Keep the left hand counting three beats and divide each beat into four sixteenths (1-e-and-a), making twelve per bar. Accent every third sixteenth in the right hand, and four evenly spaced accents emerge over the three-beat pulse.

How long is a dotted note?

A dot adds half the note's value. A dotted crotchet lasts 1.5 beats (three quavers), a dotted minim lasts three beats, and a dotted quaver lasts 0.75 of a beat (three semiquavers).

Do composers calculate odd metres before writing?

Not necessarily. Jason Zac's tune The Jellyfish turned out to be 7 + 8 + 7 + 9 = 31 counts, but it grew naturally from years of listening to progressive music rather than from planning.

Practise it

• Rhythm TeacherBuild accent patterns, divide beats and explore odd metres and polyrhythms.
• Groove MetronomeWork with tempo, accents and polyrhythms instead of a single unchanging click.
• All free music apps40 practice tools for harmony, rhythm, ear training and more.

Related lessons

• Ode to Joy Piano Tutorial: Beethoven With Rhythmic Variations and PolyrhythmsYou can make a simple melody like Beethoven's Ode to Joy sound far more sophisticated by keeping the melody unchanged and adding rhythm: choose a time feel (dividing the beat by 2, 3, 4 or 6), leave gaps in it with rhythmic devices, then layer polyrhythmic patterns such as dotted quarter notes, quarter-note triplets or dotted eighth notes.
• 5 Methods to Use and Feel Triplets in All Forms of MusicA triplet divides a beat into three equal parts, and you can learn to feel it naturally by practising triplet rhythmic devices, 3-over-2 polyrhythms, compound time such as 6/8 and 12/8, accented sets of three, and swing.
• Urvasi Bass Groove: 4 Exercises to Improve Your Timing (Part 2)To improve your timing on bass, keep a steady quarter-note pulse with your foot, imagine a sixteenth-note shaker running in your head, sing the line as you play it, and transcribe the groove onto a 1-e-and-a time grid so you know exactly where each note falls.
• Improve Your Sense of Rhythm on Piano: Time Feel, Swing and Triplets (Part 2)To build a strong time feel on piano, keep a steady pulse, divide each beat by two, three or four, choose straight or swing, and then create grooves by playing only some of the divisions or accenting them in irregular groups. In short: divide more and play less.