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When you listen to or play music, or better yet, dance to it, you are
very aware of the rhythm. You might notice that every 3rd or 4th beat
is played a little louder than the others, or that it is accented
somehow. In some types of music, several different rhythms are
performed at the same time. When that happens, it is called a
polyrhythm. Polyrhythms are a very important feature of African
In this problem you will be investigating polyrhythms, and then have
a chance to build your own so you can investigate the mathematics.
Play with the applet using the various rhythms. Experiment to find
out what it means to play a 1:2 or a 1:3 rhythm. See how the
different rhythms interact when you play them together. When a 1:2
and a 1:3 rhythm are played together, the polyrhythm is called a
2:3. The number of beats it takes a pattern to repeat itself is
the phrase length. Explore how long it takes different patterns to
- What is the ratio of the mystery polyrhythm? Explain how you know.
- Create a polyrythm of your own using two of the rhythms in the
applet. What is the ratio of
the polyrhythm and its phrase length? Explain how you know.
- A complicated polyrhythm has the ratio 2:3:4:5:6:7. What is its
phrase length? How do you know?
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