Bullroarer
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Music_insts_bullroarers2.jpg
It consists of a longish piece of cord fixed to an oval piece of wood or other suitable material which usually is thicker in the center, and sharpish at the edges.
The cord is given a slight initial twist, and the roarer is then waved in a large circle in a horizontal plane. The aerodynamics of the roarer will keep it whirling even after the initial twist has unwound.
It makes a characteristic roaring vibrato sound with notable modification from both Doppler effect and the changing speed of the roarer at different parts of its circuit.Music_insts_bullroarers1.jpg
By modifying the expansiveness of its circuit and the speed given it, the modulation of the sound can be controlled, making the coding of information possible. The low frequency component of the sound travels extremely long distances, especially on the wind.
This instrument has been used by numerous early and traditional cultures in both the northern and southern hemispheres but in the popular consciousness it is perhaps best known for its use by Australian Aborigines (it is from one of their languages that the name turndun comes).
Bull-roarers are still considered to be sacred/secret by some Aboriginal tribes and are not allowed to be shown to women, children or outsiders. They are used in men's initiation ceremonies and the sound they produced is considered to represent the sound of the Rainbow Serpent.
The bullroarer is sometimes used as a means of demonstrating the Doppler effect, by using sound. As the instrument travels round, its sound goes up or down according to its speed, and distance from the hearer.
"Bullroarer" is also a song on Midnight Oil's Diesel and Dust CD.
Bullroarer is the name of an ancestor of the Took clan of hobbits who was very tall (for a hobbit) and could ride a horse in J.R.R. Tolkien's Lord of the Rings.de:Schwirrholz