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Bullroarer

In this activity, students explore how sound production was used by ancient cultures as a communication tool over long distances.

The bullroarerrhombus, or turndun, are ancient musical instrument used in rituals for communicating over extended distances and in driving animals. These instruments date to the Paleolithic period (roughly 2.5 million years ago to 10,000 B.C.), documented in Europe, Asia, the Indian sub-continent, Africa, the Americas, and Australia.

Bullroarers are a prominent musical technology used in ceremonies, to communicate with different people groups across the continent, and as toys.

A bullroarer consists of a weighted airfoil (a rectangular thin slat of wood about 15 cm to 60 cm  long and about 1.25 cm  to 5 cm wide) attached to a long cord. Typically, the wood slat is trimmed down to a sharp edge around the edges, and serrations along the length of the wooden slat may or may not be used, depending on the cultural traditions of the region in question.

The bullroarer cord is given a slight initial twist, and the roarer is then swung in a large circle in a horizontal plane, or in a smaller circle in a vertical plane. As the instrument travels around its circular path, the pitch appears to rise and fall as it moves closer to and farther away from the listener (Doppler Effect).

By modifying the bullroarer cord's length and/or the speed with which it is turned, the sound can be altered. This can be used to code messages over far distances.

Objectives

  • Describe the properties of sound.

Materials

  • Per Student:
    a ruler with a hole in one end
    1m string

    Teacher tip: For younger student safety, cardboard Bullroarers may be made

Key Questions

  • Why might a bullroarer also be called a hummer?
  • What part of the bullroarer makes the noise?
  • How could you prove that?
  • Can you vary the sound of the hummer?

What To Do

In class:
Tie a metre-long length of string to the hole in the end of the ruler.

In a gym or outside:

  1. Space yourself out from your classmates by at least 2 metres.
  2. Twist the string 20–30 times, holding the ruler still.
  3. As you let go of the ruler, whirl the hummer in a horizontal circle over your head, finding the right speed to make a nice buzzing noise. (Be careful of other students!).

Extensions

  • Play with the length of the string and the speed to produce various sounds.
  • Try using a tool other than a ruler to see if you can make different sounds.
  • Try items like a plastic spoon or a ruler with a postcard taped to it.
  • Brainstorm uses of the bullroarer in ancient cultures.
  • How is a bullroarer similar to our hummer? How is it different?

Other Resources

How to Spin a Bullroarer| Video