Acoustics of the Australian didjeridu

Abstract

The didjeridu (or yiraki) of the Australian Aborigines is a very primitive musical instrument, both historically and acoustically. It consists simply of a more-or-less straight small tree trunk or branch, typically between one and two metres long, hollowed out by the action of fire or insects to produce a roughly tapered tube. The inside diameter typically increases from about 30 millimetres at the narrow end, from which the instrument is blown, to about 50 millimetres at the wide end, and the average wall thickness is 5 to 10 millimetres. T he bore may expand slightly at the two ends, where it can be easily scraped, and the narrow end is often given a smooth finish, for comfort in playing, by application of a resinous gum. The outside of the instrument is smoothed and painted in geometrical totemic designs, usually in black, white and orange. A didjeridu maker typically spends about two days in shaping and finishing the tube of the instrument and a further two days on the decorative painting.