didjeridu, wind instrument in the form of a straight wooden trumpet. The instrument is made from a hollow tree branch, traditionally eucalyptus wood or ironwood, and is about 1.5 metres (5 feet) long. Decorated ceremonial varieties, however, may be two or three times longer. Modern instruments may be made from a metal or plastic tube.
The didjeridu is coated with wax and resined on the blowing end, while its other end rests on the ground and is sometimes placed in an object such as a tin can for resonance. Usually the performer blows into the instrument to produce the fundamental drone pitch of the instrument, but performance techniques and playing styles vary regionally and according to the preference of the performer. Some didjeridu players tighten the lips to increase the air pressure, thereby producing overtone pitches, while other players use a technique in which they simultaneously hum and blow into the instrument, creating complex harmonic chords. Nasal (or circular) breathing, or drawing air in through the nose while expelling air from the cheeks into the instrument, is often used to produce pulsations, tonal variations, and elevations of pitch. Rhythmic and metrical patterns are created through the mouthing of various types of vocables.
Once heard only in music associated with Australian Aboriginal ritual ceremonies, such as those for sunsets, circumcisions, and funerals, the didjeridu is now also used in other contexts by Aborigines as well as in many popular- and art-music genres in the 21st century.