Mechanics of the flute
Construction and Operation of the flute
The flutes geometry and component parts
The flute is pitched at standard UK pitch (A=442Hz) and is in three sections (excluding the crown). The flute on which my work is based is the Miyazawa model PA 401RE. It has a 92.5% solid silver headjoint, body and footjoint with a 9 carat red gold riser.
The first section is the headjoint. The tubing length without the stopper is 22cm. The thickness of the tubing is approx 0.38mm. The lip-plate is coupled to the tubing via a chimney/riser which also forms the embouchure hole. Inserted in the end of the tubing is the crown and inside is the cork. The crown is also considerably heavier. The cork should be positioned 17.5mm from the front plate to the middle of the embouchure hole inside the flute. In this set position, the flute is at its most tuned. The sections of the headjoint are;
(1)The 'crown'. (2) The cork, usually natural but there are synthetic alternatives. (3) The front plate. (4) The back plate (5) The threaded rod. (This is permanently fixed to the front plate.)
The second section is the body of the flute, measuring 46.3cm in length. It houses the majority of the keywork using the Boehm system; operated by the player’s fingers is a system of keys, rods and levers which are commonly made from silver-plated nickel silver. On this model, the tone holes are open with French pointed key-arms and drawn tone holes. Coupled to the keywork are the pad cups, on the underside of which are pads. Traditional pads are made of strong thin felt, backed and covered with a doubled layer of treated membrane. The pad is stable in most climates although “Straubinger” pads were designed specifically for handmade flutes. The design of the pad ensures that it is virtually resistant to the changes in temperature and humidity that cause felt pads to expand or contract”.[1] The body is also home to the B♭ thumb key lever mechanism. It is the highest tonehole on the flute (discounting the trill and small C# toneholes).
The third section is the footjoint (approximately 13cm in length) which is home to the rod and roller for the low C, C# and E♭ keys.
The Method of sound production and radiation
The flute is an open-ended tube/pipe. The tube is the resonator, whilst the primary vibrator is the excited column of air produced by the sound source which is the player blowing a steady stream through the lips creating a velocity of airflow, directed across the far edge of the embouchure hole. “The airflow velocity can also be varied as well as the fine detailed nature of the airstream dimensions by adjusting the shape, width and height of the opening between the lips. The flautist has therefore direct control over the stability of the overblown modes.”[2]
The primary vibrator, now identified as the air jet produced through the player’s lips, oscillates either side of the edge of the embouchure hole, sporadically injecting discrete puffs of air into the air column, the puffs of air being of higher pressure (compressions) and the gaps regions of lower pressure (rarefactions). This creates a sinusoidal pressure wave containing a broad range of frequencies, some of which match the tube resonance. This results in low-amplitude *standing waves being set up which influence the fluctuation of the air across the hole.
*Two travelling waves interact to produce the standing wave in the air column. This is because as one travelling wave is set up when it reaches the end of the air column, it is reflected and inverted and the rarefaction (where the air molecules become separated) in the initial wave becomes a compression (where the air molecules are tighter) in the reflected wave.
As the hole is a displacement antinode, the low-amplitude standing waves cause the air jet to fluctuate in and out of the hole at a rate determined by the air-column resonance frequencies. These low-amplitude standing waves are reinforced and although the wave is reflected and there is partial loss of wave energy, the instrument sounds, the sustained note sounded being determined by the number of holes open or closed (operated by the players fingers) which will lengthen or shorten the vibrating air column. An analogy of this would be if you were to cut off the remainder of the flute - as each key is systematically released, each note would have the same wavelength as if the flute was one length.
The flute’s resonator acts as a sound modifier, the sound source being the blown air from the lips “the amplitude relationship between the pipe/flutes modes is governed by the material from which the pipe/flute is constructed and the diameter of the pipe/flute with respect to its length” [3]
I took measurements of a selection of flutes, using a Vernier gauge, to demonstrate that flutes vary in size between different makers; each flute varies in terms of materials and dimensions, particularly in the size of the embouchure hole, which I believe will have a bearing on its sound production, as this is where the column of air hits. The material’s density would also deeply affect the resonance. Further investigations made showed the differences in amplitude and harmonics, but I felt them to be too in-depth for this article. It was clear from the evidence that material and dimensions did account for differences within the harmonics and that the differences in metals and dimensions demonstrated that amplitude varied most in the 1st and 2nd peaks and the frequency in the 3rd and 4th. This experiement is not conclusive, as the air pressure via the lips could not be measured exactly and it is not possible to calculate which change is due to measurements and which to metal, although the fact that the Yamahas are of almost exactly the same dimensions, but of different metals provides significant evidence that different metals do affect the sound production and radiation.
The Flute’s Pitch range
The normal range of fully chromatic notes on a concert flute is from the lowest, C4 (unless a B♭ footjoint is added as an alternative to the common C footjoint), to the highest, C7. Although there are some higher notes, C7 is considered to be the highest in the standard flute range. The notes are changed by opening the holes/keys to reduce the effective length of the air column or by overblowing. In addition to notes produced by opening and closing of key work, “because the air column is cylindrical and open at both ends, its resonance frequencies form a complete harmonic series so the flute overblows to the octave.“ [4] Also, “by varying the air pressure, a flute player can also change the pitch of a note by causing the air in the flute to resonate at a harmonic other than the fundamental frequency without opening or closing any holes.” [5]
The tuning of the instrument is by reducing or increasing the air column length, usually via the headjoint which is used as a slide and is pushed in or pulled out to the required pitch. When pushed in fully, most flutes are pitched at A = 442, which is why most flutes will always need to be pulled out a little. The headjoint cork stopper is positioned so that the instrument will play in tune, but is not used by the player for fine tuning.
Timbre and other musical or playing features
Timbre or sometimes tone colour is our perception and is associated with sound quality. The flute may be described as being mellow, rich, open, bright, dark, etc. This is largely dependent on which material the instrument is made from. For example, gold being denser than silver will have more resistance, therefore the perceived sound we hear will be richer meaning it has lower harmonics. Timbre is also dependent on the listeners hearing. Dynamics also affect the timbre, as to play louder you need to increase air stream and have the correct air stream angle.
Other musical features that affects sound is articulation (movement of the tongue to separate the notes/stop air flow) the player’s positioning of the tongue such as in the French articulation the attack is softer whereas the German articulation is much harsher and is often used by beginner flute players, pronunciation with staccato, legato, semi-legato also affect the sound made and heard. There is of course the fundamental issues of breathing and breath control. Many new flutists will begin with breathy sounds and aim to eradicate them as they progress.
[1] http://www.miyazawa.co.uk/images/pads_straubinger.jpg, 17th August 2009
[2] David M. Howard & Jamie Angus, Acoustics and Psychoacoustics Focal Press pg 182
[3] David M. Howard & Jamie Angus, Acoustics and Psychoacoustics Focal Press pg.178.
[4] The Open University, TA212 The Technology of Music, Block 3:1, pg. 83.
[5] http://en.wikipedia.org/wiki/Flute, 16th August 2009
The flutes geometry and component parts
The flute is pitched at standard UK pitch (A=442Hz) and is in three sections (excluding the crown). The flute on which my work is based is the Miyazawa model PA 401RE. It has a 92.5% solid silver headjoint, body and footjoint with a 9 carat red gold riser.
The first section is the headjoint. The tubing length without the stopper is 22cm. The thickness of the tubing is approx 0.38mm. The lip-plate is coupled to the tubing via a chimney/riser which also forms the embouchure hole. Inserted in the end of the tubing is the crown and inside is the cork. The crown is also considerably heavier. The cork should be positioned 17.5mm from the front plate to the middle of the embouchure hole inside the flute. In this set position, the flute is at its most tuned. The sections of the headjoint are;
(1)The 'crown'. (2) The cork, usually natural but there are synthetic alternatives. (3) The front plate. (4) The back plate (5) The threaded rod. (This is permanently fixed to the front plate.)
The second section is the body of the flute, measuring 46.3cm in length. It houses the majority of the keywork using the Boehm system; operated by the player’s fingers is a system of keys, rods and levers which are commonly made from silver-plated nickel silver. On this model, the tone holes are open with French pointed key-arms and drawn tone holes. Coupled to the keywork are the pad cups, on the underside of which are pads. Traditional pads are made of strong thin felt, backed and covered with a doubled layer of treated membrane. The pad is stable in most climates although “Straubinger” pads were designed specifically for handmade flutes. The design of the pad ensures that it is virtually resistant to the changes in temperature and humidity that cause felt pads to expand or contract”.[1] The body is also home to the B♭ thumb key lever mechanism. It is the highest tonehole on the flute (discounting the trill and small C# toneholes).
The third section is the footjoint (approximately 13cm in length) which is home to the rod and roller for the low C, C# and E♭ keys.
The Method of sound production and radiation
The flute is an open-ended tube/pipe. The tube is the resonator, whilst the primary vibrator is the excited column of air produced by the sound source which is the player blowing a steady stream through the lips creating a velocity of airflow, directed across the far edge of the embouchure hole. “The airflow velocity can also be varied as well as the fine detailed nature of the airstream dimensions by adjusting the shape, width and height of the opening between the lips. The flautist has therefore direct control over the stability of the overblown modes.”[2]
The primary vibrator, now identified as the air jet produced through the player’s lips, oscillates either side of the edge of the embouchure hole, sporadically injecting discrete puffs of air into the air column, the puffs of air being of higher pressure (compressions) and the gaps regions of lower pressure (rarefactions). This creates a sinusoidal pressure wave containing a broad range of frequencies, some of which match the tube resonance. This results in low-amplitude *standing waves being set up which influence the fluctuation of the air across the hole.
*Two travelling waves interact to produce the standing wave in the air column. This is because as one travelling wave is set up when it reaches the end of the air column, it is reflected and inverted and the rarefaction (where the air molecules become separated) in the initial wave becomes a compression (where the air molecules are tighter) in the reflected wave.
As the hole is a displacement antinode, the low-amplitude standing waves cause the air jet to fluctuate in and out of the hole at a rate determined by the air-column resonance frequencies. These low-amplitude standing waves are reinforced and although the wave is reflected and there is partial loss of wave energy, the instrument sounds, the sustained note sounded being determined by the number of holes open or closed (operated by the players fingers) which will lengthen or shorten the vibrating air column. An analogy of this would be if you were to cut off the remainder of the flute - as each key is systematically released, each note would have the same wavelength as if the flute was one length.
The flute’s resonator acts as a sound modifier, the sound source being the blown air from the lips “the amplitude relationship between the pipe/flutes modes is governed by the material from which the pipe/flute is constructed and the diameter of the pipe/flute with respect to its length” [3]
I took measurements of a selection of flutes, using a Vernier gauge, to demonstrate that flutes vary in size between different makers; each flute varies in terms of materials and dimensions, particularly in the size of the embouchure hole, which I believe will have a bearing on its sound production, as this is where the column of air hits. The material’s density would also deeply affect the resonance. Further investigations made showed the differences in amplitude and harmonics, but I felt them to be too in-depth for this article. It was clear from the evidence that material and dimensions did account for differences within the harmonics and that the differences in metals and dimensions demonstrated that amplitude varied most in the 1st and 2nd peaks and the frequency in the 3rd and 4th. This experiement is not conclusive, as the air pressure via the lips could not be measured exactly and it is not possible to calculate which change is due to measurements and which to metal, although the fact that the Yamahas are of almost exactly the same dimensions, but of different metals provides significant evidence that different metals do affect the sound production and radiation.
The Flute’s Pitch range
The normal range of fully chromatic notes on a concert flute is from the lowest, C4 (unless a B♭ footjoint is added as an alternative to the common C footjoint), to the highest, C7. Although there are some higher notes, C7 is considered to be the highest in the standard flute range. The notes are changed by opening the holes/keys to reduce the effective length of the air column or by overblowing. In addition to notes produced by opening and closing of key work, “because the air column is cylindrical and open at both ends, its resonance frequencies form a complete harmonic series so the flute overblows to the octave.“ [4] Also, “by varying the air pressure, a flute player can also change the pitch of a note by causing the air in the flute to resonate at a harmonic other than the fundamental frequency without opening or closing any holes.” [5]
The tuning of the instrument is by reducing or increasing the air column length, usually via the headjoint which is used as a slide and is pushed in or pulled out to the required pitch. When pushed in fully, most flutes are pitched at A = 442, which is why most flutes will always need to be pulled out a little. The headjoint cork stopper is positioned so that the instrument will play in tune, but is not used by the player for fine tuning.
Timbre and other musical or playing features
Timbre or sometimes tone colour is our perception and is associated with sound quality. The flute may be described as being mellow, rich, open, bright, dark, etc. This is largely dependent on which material the instrument is made from. For example, gold being denser than silver will have more resistance, therefore the perceived sound we hear will be richer meaning it has lower harmonics. Timbre is also dependent on the listeners hearing. Dynamics also affect the timbre, as to play louder you need to increase air stream and have the correct air stream angle.
Other musical features that affects sound is articulation (movement of the tongue to separate the notes/stop air flow) the player’s positioning of the tongue such as in the French articulation the attack is softer whereas the German articulation is much harsher and is often used by beginner flute players, pronunciation with staccato, legato, semi-legato also affect the sound made and heard. There is of course the fundamental issues of breathing and breath control. Many new flutists will begin with breathy sounds and aim to eradicate them as they progress.
[1] http://www.miyazawa.co.uk/images/pads_straubinger.jpg, 17th August 2009
[2] David M. Howard & Jamie Angus, Acoustics and Psychoacoustics Focal Press pg 182
[3] David M. Howard & Jamie Angus, Acoustics and Psychoacoustics Focal Press pg.178.
[4] The Open University, TA212 The Technology of Music, Block 3:1, pg. 83.
[5] http://en.wikipedia.org/wiki/Flute, 16th August 2009