groups in the most northerly areas. Clapsticks A clapstick is a type of musical instrument that, according to western musicological classification, falls into the category of percussion. Unlike drumsticks, which are generally used to strike a drum, clapsticks are intended for striking one stick on another, and people as well. They are of oval shape with paintings of snakes, lizards, birds and more. Gum leaf Used as a hand-held free reed instrument. Bullroarer A bullroarer consists of a weighted airfoil (a rectangular thin slat of wood about (6 in) to (24 in) long and about (0.5 in) 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. Audio/visual demonstration Sound modulation by changing orbital plane. The low-frequency component of the sound travels extremely long distances, clearly audible over many miles on a quiet night. Various cultures have used bullroarers as musical, ritual, and religious instruments and long-range communication devices for at least 19,000 years. Bullroarers have been used in initiation ceremonies and in burials to ward off evil spirits, bad tidings, and especially women and children. Bullroarers are considered secret men's business by all or almost all Aboriginal tribal groups, and hence forbidden for women, children, non-initiated men, or outsiders to even hear. Fison and Howitt documented this in "Kamilaroi and Kurnai" (page 198).