Bullroarer
A bullroarer consists of a weighted airfoil (a rectangular thin slat of wood about 15 to 60 centimetres (6
to 20 in) long and about 1.2 to 5 centimetres (0.5 to 2 in) 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 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. The aerodynamics of the roarer will keep it spinning about its axis even after the initial twist has unwound. The cord winds fully first in one direction and then the other, alternating.
It makes a characteristic roaring vibrato sound with notable sound modulations occurring from the rotation of the roarer along its longitudinal axis, and the choice of whether a shorter or longer length of cord is used to spin the bullroarer. By modifying the expansiveness of its circuit and the speed given it, and by changing the plane in which the bullroarer is whirled from horizontal to vertical or vice versa, the modulation of the sound produced can be controlled, making the coding of information possible.
The low-frequency 2component of the sound travels extremely long distances, clearly audible over many miles on a quiet night
The 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. The aerodynamics of the roarer will keep it spinning about its axis even after the initial twist has unwound. The cord winds fully first in one direction and then the other, alternating.
It makes a characteristic roaring vibrato sound with notable sound modulations occurring from the rotation of the roarer along its longitudinal axis, and the choice of whether a shorter or longer length of cord is used to spin the bullroarer. By modifying the expansiveness of its circuit and the speed given it, and by changing the plane in which the bullroarer is whirled from horizontal to vertical or vice versa, the modulation of the sound produced can be controlled, making the coding of information possible.
The low-frequency 2component of the sound travels extremely long distances, clearly audible over many miles on a quiet night