Harmonics

The didgeridoo is a wind instrument of the Indigenous Australians of northern Australia. It is sometimes described as a natural wooden trumpet or drone pipe. Musicologists classify it as an aerophone. Some sources state that the didgeridoo had other uses in ancient times.

It is usually cylindrical or conical in shape and can measure anywhere from 3 to 9 feet in length. Generally, the longer the instrument, the lower the pitch or key of the instrument. Keys from D to F are the preferred pitch of traditional Aboriginal players. The didjeridoo functions as an aural kaleidoscope of timbres and the extremely difficult virtuoso techniques developed by expert performers find no parallel elsewhere.

There are no reliable sources stating the didgeridoo’s exact age, though it is commonly claimed to be the world’s oldest wind instrument. Archaeological studies of rock art in Northern Australia suggests that the Aboriginal people of the Kakadu region of the Northern Territory have been using the didgeridoo for about 1500 years, based on the dating of paintings on cave walls and shelters from this period. A rock painting in Ginga Wardelirrhmeng from the freshwater period 1500 years ago shows a didgeridoo player and two songmen. In some Aboriginal cultures, only men are permitted to play it, and women can only use clapsticks.

Authentic Aboriginal didgeridoos are produced in traditional communities in Northern Australia and are usually made from hardwoods, especially the various eucalyptus species that are endemic to the region. Sometimes a native bamboo or pandanus is used. Generally, the main trunk of the tree is harvested, though a substantial branch may be used instead. Aboriginal didgeridoo craftsmen spend considerable time in the challenging search for a tree that has been hollowed out by termites to just the right degree. If the hollow is too big or too small, it will make a poor quality instrument.

When a suitable tree is found and cut down, the segment of trunk or branch that will be made into a didgeridoo is cut out. The bark is taken off, the ends trimmed, and some shaping of the exterior then results in a finished instrument. It may then be painted or left undecorated. A rim of beeswax may be applied to the mouthpiece end. Traditional instruments made by Aboriginal craftsmen in Arnhem Land are sometimes fitted with a wax mouthpiece. This comes from wild bees and is black in appearance with a distinctive aroma.

Didgeridoos are also made from PVC piping. These generally have a 1.5 to 2 inch inside diameter, and have a length corresponding to the desired key. The mouthpiece is often made of the traditional beeswax, or duct tape. An appropriately sized rubber stopper with a hole cut into it is equally acceptable. Some have also found that finely sanding and buffing the end of the pipe creates a sufficient mouthpiece.

The didgeridoo is played with continuously vibrating lips to produce a drone while using a special breathing technique called circular breathing. This requires breathing in through the nose while simultaneously expelling air out of the mouth using the tongue and cheeks. By use of this technique, a skilled player can replenish the air in their lungs, and with practice can sustain a note for as long as desired. Recordings exist of modern didgeridoo players playing continuously for more than 40 minutes. Mark Atkins, in Didgeridoo Concerto plays for over 50 minutes continuously.

A termite bored didgeridoo has an irregular shape that usually increases in diameter towards the lower end. This shape means that its resonances occur at frequencies that are not harmonically spaced in frequency. This contrasts with the harmonic spacing of the resonances in a cylindrical plastic pipe, whose resonant frequencies fall in octaves, fifths and fourths. The second resonance of a didgeridoo, or the note sounded by overblowing, is usually around an 11th higher than the fundamental frequency.

The vibration produced has specific harmonics. It has frequency components falling exactly in the ratios of octaves, fifths and fourths. However, the nonharmonic spacing of the instrument’s resonances means that the harmonics of the fundamental note are not systematically assisted by instrument resonances, as is usually the case for Western wind instruments.

Sufficiently strong resonances of the vocal tract can strongly influence the timbre of the instrument. At some frequencies, depending on the position of the player’s tongue, resonances of the vocal tract inhibit the oscillatory flow of air into the instrument. Bands of frequencies that are not thus inhibited produce variations in the output sound. These variations give the instrument its readily recognizable sound.

Other variations in the didgeridoo’s sound are made with “screeches” related to sounds emitted by Australian animals, such as the dingo or the kookaburra. To produce these sounds the player simply has to cry out in the didgeridoo while continuing to blow air through it. The results range from very high pitched sounds to much lower guttural vibrations.

The didgeridoo is sometimes played as a solo instrument for recreational purposes, though usually it accompanies dancing and singing in ceremonial rituals. For Aboriginal groups of northern Australia, the didgeridoo is an integral part of ceremonial life, as it accompanies singers and dancers in religious rituals. Pair sticks, sometimes called clapsticks or bilma, establish the beat for the songs during ceremonies. The rhythm of the didgeridoo and the beat of the clapsticks are precise, and these patterns have been handed down for many generations. Only men play the didgeridoo and sing during ceremonial occasions, whilst both men and women may dance. The taboo against women playing the instrument is not absolute. Female Aboriginal didgeridoo players did exist, although their playing generally took place in an informal context and was not specifically encouraged. Linda Barwick, an ethnomusicologist, says that women have traditionally not played the didgeridoo in ceremony, but in informal situations there is no prohibition.

The didgeridoo was also used as a means of communication across far distances. Some of the sound waves from the instrument can be perceived through the ground or heard in an echo. Each player usually has his own base rhythm which enables others to identify the source of the message.

There are sacred and even secret versions of the didgeridoo in Aboriginal communities in parts of Arnhem Land, Northern Territory, and the surrounding areas. These types of instruments have specific names and functions and some of these are played like typical didgeridoos whereas others are not.

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