Air sounds may be produced by blowing across the flute in normal playing position or down into the embouchure hole, and different combinations of air and pitch can be used.
Air sounds (sometimes also called residual or aeolian sounds) are created through blowing an airstream across the embouchure hole. Air sounds can be produced at producing varying dynamics, but frequent breaths are required to sustain a loud sound. The pitch is dictated by the fingerings of the flute, although no tone is produced in the normal sense. The air stream can be difficult to control (especially if a sound without any pitched note is required), but different positions of the flute in relation to the mouth may be considered (eg turning the flute away from the mouth, or moving the flute as a whole away from the player). If the flute's position is to move considerably away from the usual playing position, it is necessary to allow time to move to and from that position for the effect to be most reliable. Frequent breaths are needed and amplification may be required.
It is possible to move smoothly from an air sound to a normal tone and back again, or to combine elements of pitch and air in the sound.
Transition from air to pitched note and back again
As above but trilled
With all air sounds, air use is highly uneconomic and breaths are required every few seconds. This can be extremely fatiguing for players, so prolonged passages of air sounds, especially at loud dynamic levels, should be avoided.
Jet whistles are produced by blowing a fast air stream into the embouchure hole, producing a pitched sound which contains many harmonics. A loud sound cannot be sustained for more than a few seconds on the alto flute due to the amount of air used. This is most effective using the lowest pitches of the instrument, as a greater harmonic spectrum is available from these notes.
A jet whistle may be modified through changing the flute's position against the lip (ie by rolling out), to bring out the upper partials in the sound. Changing the vowel shape inside the mouth can also have an impact on the type of sound, as well as the pitch, produced.
Generally speaking, jet whistles are more difficult to achieve and often less effective on the lower flutes than the C flute, due to the amount of air required and fewer higher partials in the sound.
A gentle air stream through the instrument produces a much softer, unpitched effect, which can be more sustainable, but very frequent breaths are needed.
Gentle air stream into the flute
Unlike other wind instruments, it is not practical to breathe in through the instrument on an alto flute, as the breath itself does not travel through the flute. Inwards breath sounds are not naturally particularly noisy, and by creating a deliberately noisy in-breath for musical purposes it is likely that the player will then have to breathe in again in order to have a suitable amount of air to play. The alto flute uses large volume of air and for this reason it is advisable to avoid incorporating controlled breathing sounds into a composition. Players have varying lung capacities and breathing too frequently in a specifically noisy way can easily cause discomfort to the player or hyper-ventilation. As an alternative, it is recommended that one solution to incorproate breathing sounds into a composition if for them to be pre-recorded and used as part of an electronics part.
Notation of air sounds
Air sounds range from breathy pitched notes to jet whistles. There is no standardised notation for these effects - those shown below are merely suggestions. Ensure all notations are shown in a glossary.
Pure air sounds
Pure air sounds transition to pitch