Any cracks that occur anywhere along the length of a didgeridoo will reduce both the

quality and volume of the sound it produces and will alter the key of the instrument.

Often didgeridoos are made from unseasoned and/or inadequately prepared and finished timbers. It is extremely important that your instrument is properly seasoned and finished to eliminate this singularly most detrimental factor affecting sound quality.

An important note regarding the nature of timber is its unpredictability over time. Even well seasoned timber that has been professionally treated has an unpredictable nature. This is particularly relevant with the types of timbers used for the crafting of termite hollowed didgeridoos. Although minor cracks can appear in any timber products over time, proper preparation, treatment and finishing will significantly minimise this.

A musical instrument must be tuned to a specific key or note if it is to be played with other music. This also applies to the didgeridoo even though it is a fixed length instrument.

It is interesting to note that besides length, a number of other factors affect the key that any given didgeridoo will produce. Changes in air temperature, pressure and humidity as well as the player's lip, mouth, throat and lung sizes all have an effect on the final note produced. The exact characteristics of the didgeridoo change with the day and the player, making it a truly unique and individual instrument.

Sound quality is severely and adversely affected by the presence of any air leaks anywhere along the length of an instrument. Improperly finished and/or seasoned timber will often cause this problem. Besides these detrimental problems, there are other factors, which also have an effect on the quality and character of the sound produced by a didgeridoo.

1) Tonal Quality of the Sound

The human ear responds to musical sound in an interesting, perhaps peculiar way. ‘Pure’ notes; i.e., notes that are produced without overtones are not as enjoyable to us as ‘dirty’ or ‘full’ notes, containing many overtones. Pure notes, in reference to wind instruments, are produced by a smooth bore. Eg, a piece of PVC pipe, or bored out piece of timber, whereas full notes are produced by an irregular, contoured bore.

In an authentic termite hollowed didgeridoo, there are many channels and irregularities running up the centre of the instrument. These have been formed by nature in a completely individual and random way in each didgeridoo. The sound produced by a genuine termite hollowed instrument is unique and complex in ways that are not yet understood. Hundreds and perhaps thousands of overtones are produced by these irregular contours. This is part of what gives this instrument its remarkably subtle, full and earthy tones.

2) Resonance and Sharpness (or “Edge”)

These two attributes are often mutually exclusive because they are predominantly governed by the inside bore diameter of the instrument, although in some cases both are present in larger bore didgeridoos. Such an instrument—one with a full, all encompassing resonance and the ability to deliver a sound that would make you think was going to break glass may be more scarce but certainly not impossible to find.

Both these attributes have their advantages and disadvantages. A large bore, warm, resonant sounding didgeridoo will fill a space with a sound and feeling that can almost be touched. It is capable of creating a mood of solemnity and reflection where the sound is experienced through the sense of ‘feel’, both on a physical and emotional level.

Such an instrument is not as easy to play fast rhythms on and due to its warmth and softness, it can sometimes be lost to perception when played at a constant level and combined with other instruments throughout the duration of a tune. An instrument with a sharp edge to its sound often has a small diameter bore, and thus lacks the fuller base sound of the larger bore. The sharpness of such an instrument is heightened by its absence of a full, resonant base characteristic. This allows the didgeridoo to ‘cut’ because of its sharper edge and when combined with other base instruments, has a similar effect that a lead guitar can have. Another advantage of a smaller bore instrument is that it requires less air to play and therefore is more suitable for a beginner; or player who wishes to make rhythms which would require lots of air on a larger bore didgeridoo or long spaces between breathing cycles. (As will be explored later, backpressure also effects ease of playability, particularly for a beginner, meaning that not all small bore didgeridoos are easy to play—even if they do not require as much air to operate). Such an instrument lends itself to being played faster than one in the same key of a larger bore.

Amplification can help to add a fullness to the smaller bore didgeridoos, particularly if levels are adjusted, so it is not so much that ‘base is better’, but rather, what the instrument’s intended use is to be.

A poorly formed mouthpiece will make the playing process extremely difficult and virtually impossible for the novice to learn at all. If the diameter is too large or small, or the shape is poorly formed, a good didgeridoo can become almost impossible to play. The type of wax used to form the mouthpiece is also a significant contributing quality factor.

In simple terms back-pressure is the amount of air pressure asserted back onto a player’s lips by the standing wave or base drone/harmonic of a didgeridoo. An instrument with excellent backpressure is one whose backpressure characteristics are ‘middle of the road’—not too high and not too low. A good backpressure didgeridoo is easiest for a novice to learn on because it ‘falls’ into the note easily, without effort and will keep the player’s lips vibrating within the ‘frequency band’ created by the backpressure characteristics. This means that a new player will be able to maintain the note of the instrument easier and for longer. The ‘frequency band’ or how far the note can be ‘bent’ or altered up and down from the note of the instrument, is narrow on a good backpressure didgeridoo. This means that although such an instrument is easy to play, its key cannot be as readily ‘bent’, something that adds to the versatility of a player’s repertoire—herein is the advantage of a lower or higher backpressure instrument.

A good backpressure didgeridoo is easy to play while a lower or higher backpressure instrument is slightly harder to master, but a little more versatile. A poor backpressure instrument would be one which is too high or low on the backpressure scale to be practical to play.

Responsiveness is the ability of an instrument to ‘keep up’ with fast rhythms and changes a player makes during playing. The longer an instrument or the larger the bore diameter, the less responsive it will generally be. This is because more air volume is contained within the instrument bore and therefore it takes more time and effort to move and change it. Another way of saying this is that there is a lag between a player’s input and the reaction that results. This lag is always there in any instrument and is more pronounced in a longer/larger bore didgeridoo.

It follows from this that a short, large bore didgeridoo would be expected to have similar responsiveness to a longer, smaller bore instrument.

An instrument with good vocal projection will clearly transfer a player’s voice through itself to the listener. Clarity and volume of the vocals projected will determine the vocal standard of the didgeridoo.

Some didgeridoos use a lot of air from the player to keep them going. Fast and complex rhythms add to the burden of a player to keep air up to their instrument and therefore air usage is an important consideration in didgeridoo assessment. Generally, the larger bore didgeridoos use more air. Length is not so much of an issue here, and backpressure that is middle of the road will reduce the air requirements of any given instrument.

The volume of sound produced by a didgeridoo is very dependent on its individual shape. If the centre hole decreases in size anywhere along the length, the didgeridoo's potential for volume is reduced. The best shape for greatest volume is conical with the bottom section of the instrument ‘flaring’ more rapidly—like a megaphone, where the end or ‘bell’ finishes with a significantly larger diameter than the mouthpiece end. A bottom end diameter of 200mm and larger will make a good difference in volume as opposed to a similar instrument without such a large conical finish.

Curves and conical shapes also affect key, and can cause quite unpredictably different results than what might be expected.

NOTE: Volume has nothing to do with sound quality and an excessively loud didgeridoo can sometimes become an annoyance to everyone—including the player! Consideration in regards to transport and protection should also be taken into account when thinking of purchasing a ‘large bell’ didgeridoo as damage to it can occur much easier. With the modern advantages of amplification, an instrument with good tonal qualities, but not necessarily loud in regards to volume, can be a better long-term choice.

Finally, it is better to look at all these factors—resonance or sharpness, low or high volume, and low or high backpressure as attributes of the personality of a didgeridoo and not as one attribute being better than the other. A player’s individuality will also affect the final character of the sound produced by each instrument. The choice you make should be based on what you want from your instrument. And remember that you will probably never get everything you want in any one didgeridoo, because they are like people—each completely individual and rarely perfect in all the ways you would like them to be!

Traditionally, the style of artwork, which appears on the didgeridoo, is that of the Australian Aboriginal. As popularity for the artwork from this culture has increased, many copies and fakes have appeared. This has been particularly true in regards to the artworks placed on ornamental or 'tourist' didgeridoos. Besides the fact that there is so much mass produced non-genuine indigenous artwork on the market, there are also ethical concerns involved.