There are several different possibilities for multiple sonorities, created through a combination of careful embouchure control and throat tuning (using the mouth and throat to give extra resonance). Multiphonics are naturally microtonal and each has its own particular tone colour, with certain component pitches naturally stronger than others, although this can be controlled to some extent by the player. When writing multiphonics, fingerings should ALWAYS be given as a guide. Fingerings fall roughly into three categories:
Using the principles of harmonics, octaves and other intervals may produced by overblowing a fundamental. Octaves are the simplest of these to produce, but smaller intervals in the harmonic series are also possible, although they can sometimes be difficult to control. A rich harmonic multiphonic can be produced from the very lowest notes of the instrument, incorporating up to five pitches.
Underblown high pitches may also create multiphonic effects. Any note from d''' upwards can be ‘split’ to create one, or sometimes more, pitches below it. These underblown pitches often have microtonal intonation, and frequently have a c'' or c#'' as their lowest note.
Other multiphonics may be produced through specially created fingerings, which may in some cases require the player to move the hands away from the usual positions. Time should be given to allow for these hand movements. The Kingma System allows for greater versatility of multiphonics from special fingerings, since the venting from the extra open holes enables chromatic movement of some multiphonics through the instrument.
Each multiphonic requires a different air angle and embouchure position, and some are more stable and reliable than others. The combination of notes available as multiphonic chords is large. C flute multiphonic fingerings, as listed in books such as The Other Flute by Robert Dick, will often work on the Kingma System bass flute, sounding an octave lower than written, but changes to the balance of pitches within the multiphonic may be encountered, and some notes may not sound at all, while others emerge, due to the different size of the instrument's tube.
Notation of multiphonics
Multiphonics may be written normally as chords, but an indication should be given regarding the fingering to be used. The example below shows a special fingering, followed by an underblown a''' and a harmonic multiphonic.