Flute
The flute is a musical instrument of the woodwind family. A musician who plays the flute is sometimes called a flutist or flautist.
(Public domain image from Websters Dictionary 1911)
A flute is usually an open-ended reedless tube with circular holes, which produce higher or lower sounds when opened or closed with the fingers. The tone is most usually produced either by blowing horizontally across a hole located near one end of the instrument or by blowing vertically through a narrow channel against a sharp edge.
Flute sounds are typically open and hollow as a result of relatively weak upper partials. As a result, flute tones are sweet in character and blend well with other instruments. The flute's timbre, pitch and attack are flexible, allowing a very high degree of instantaneous expressive control.
In western classical music the standard concert flute is pitched in C and has a range of about 3 octaves starting from middle C. Also commonly used in orchestras is the piccolo, a small flute usually pitched an octave above the concert flute. Alto and bass flutes, pitched a fourth and an octave below the concert flute, are used occasionally. Many other sizes of flute and piccolo are used from time to time, including soprano flutes in Eb, and Db instruments used principally in older wind band music.
The modern professional concert flute is generally made of silver, gold, or combinations of the two. Student instruments are usually made of of nickel silver, or silver-plated brass. Wooden flutes and headjoints are increasingly popular. The dimensions and key system of the modern western concert flute and its close relatives are almost completely the work of the great flutist, composer, acoustician and silversmith, Theobald Boehm, who described his invention in his 1871 book, "The Flute and Flute Playing." Minor additions to and variations on his key system are common but the acoustical struture of the tube remains almost exactly as he designed it.
Boehm's key system, with minor variations, continues to be regarded as the most effective system of any modern woodwind, allowing trained players to perform with facility in all keys and with extraordinary velocity and brilliance.
Types of Flute
Flutes may be either transverse or end-blown, and their tubes may be either open or closed.
The familiar concert flute, piccolo, and fife are examples of transverse flutes, in which air is blown from the mouth across a small hole at the top of the instrument. In a transverse flute the embouchure (position of the lips and tongue) is the main determining factor in tone production (as well as having an effect on pitch).
End blown flutes, include the recorder, organ pipe, ocarina, and the tin whistle. In these, the stream of air is directed by a pathway against a blade. The embouchure is less critical, though is still important in mastery of the finer points of playing. Nose flutes exist in some cultures.
Flutes may also be either open or closed-ended. The organ pipe, ocarina, pan-pipes, concert whistle, jug, police-whistle and bosun's whistle are common examples. Open-ended flutes such as the concert flute and recorder have more harmonics, and thus more flexibility for the player, and brighter, more pleasing timbres.
Production of sound
A flute produces sound when a stream of air directed across the top of a hole bounces in and out of the hole. Some engineers have called this a fluidic multivibrator, because it forms a mechanical analogy to an electronic circuit called a multivibrator.
The stream beats against the air in a resonator, usually a tube. The player changes the pitch of the flute by changing the effective length of the resonator. This is done either by closing holes, or more rarely, with a slide similar to a trombone's slide.
Because the air-stream is lower mass than most of the resonators used in instruments, it can beat faster, but with less momentum. As result, flutes tend to be softer, but higher-pitched than other sound generators of the same size.
To be louder, a flute must use a larger resonator, and a wider air-stream. A flute can generally be made louder by making its resonator and tone-hole wider. This is why police whistles, a form of flute, are very wide for their pitch, and why organs can be far louder than concert flutes: an organ pipe's tone-hole is usually eight or more times wider.
The air-stream must be flat, and precisely aimed at the correct angle and velocity, or it will not vibrate. In end-blown flutes, a precisely machined slot extrudes the air. In organs, the air is supplied by a regulated blower.
In a transverse flute, especially the concert flute and piccolo, the player must form and direct the stream with his lips. This makes the transverse flute's pitch and timbre more instantly expressive than any other instrument. However, it also makes the transverse flute immensely more difficult to play than the recorder.
Generally, the quality called "tone color" or "timbre" varies because the flute produces harmonics in different intensities. A harmonic is a frequency that's an even multiple of the lowest, or "fundamental" tone of the flute. When a flute sounds harsh, or whiny, it is being played to provide more harmonics. Generally the air-stream is thinner (to vibrate in more modes), faster (providing more energy to vibrate), and aimed across the hole more shallowly (permitting a more shallow deflection of the airstream to resonate).
Almost all flutes can be played in fundamental, octave, tierce, quatre and cinque modes simply by blowing harder and making the air-stream move more quickly and at a more shallow angle. Flute players select their instrument's resonant mode with embouchure and breath control, much as brass players do.
The timbre is also affected by the quality of the resonator. Generally, more rigid resonators (such as wood) have a "dead" sound, because they have a higher acoustic impedance, and do not resonate with the harmonics. Concert flutes are expected to produce a "brilliant" sound, with a wide range of harmonics. To help this, they are thin tubes made of hard-drawn silver or gold alloys. These are more mechanically elastic than wood, and therefore vibrate in more modes. Theoretically, flutes constructed in thin tubes of elastic but heavy metals, such as alloys of gold, tungsten, platinum or osmium sound "richer" because they vibrate to a lower, therefore more audible range of harmonics. This effect also explains the good tone of bronze and brass flutes, which are less massive, but more elastic.
Appearance and development
The precursors of the modern flute were keyless wooden transverse flutes, similar to modern fifes. Later these were modified to to be well-tempered, and include between 1 and 8 keys to aid in producing chromatic notes. The most common pitch for such flutes was and remains D, but other pitches sometimes occur. These simple system flutes continue to be used in folk music (particularly Irish traditional music) and in "historically informed" performances of baroque (and earlier) music.
Construction and Materials
Concert flutes have three parts: the head, the body, and the extension. The head contains a tuning-cork (or plug) for precision tuning, adjusted by the head-end knob. Gross, temporary adjustments of pitch are made by moving the head in and out of the head-joint. The player makes fine, or rapid adjustments of pitch and timbre by adjusting their embouchure.
Often, a different head can make the flute play like a different flute. It is critical.
The most common mechanical options of flutes are "offset E" keys, "split E" modification, and a "B foot." All of Boehme's original models had offset-E keys, which are mechanically simpler, and permit a more relaxed hand position, especially for younger players. Offset-E keys are more common on less-expensive flutes, but available on almost all makes at every level of expense. The in-line E was originally invented because it was easier to manufacture, and was used by the better commercial flutes. The split E modification makes the 3rd octave E easier to play for some players. The B foot extends the range of the flute down to B below middle C.
Trill keys permit rapid alternation between two notes. False fingerings using the trill keys also permit a skilled player to reach four octaves of range, though the "natural" range is three octaves. Boehm's fingering is also used in saxophones, and many flute players therefore "double" on this instrument for jazz and small ensembles.
Less-expensive flutes are constructed of nickel alloys, possibly silver-plated. More expensive flutes are made of silver alloys. Flutes have been constructed of gold, platinum, wood, glass and many other materials.
The tubes are usually drawn, Tone-holes may be either drawn or soldered. The rest of the mechanism is constructed by lost-wax castings and machining, with mounting posts silver-soldered to the tube. On the best flutes, the castings are forged to increase their strength.
The head end is the most difficult part to construct, because it is a long thin parabola. The lip-rest and tone-hole have critical dimensions, edges and angles, which vary slightly in different models. Fortunately, once made, these never need adjustment.
The tube connecting the embouchere hole of the lip-plate to the head has a critical length. The shorter the hole, the more quickly a flute can be played. The longer the hole, the more expressive and beautiful the tone.
The holes are stopped by pads constructed of fish skin (gold-beater's skin) over felt, or in some very low-cost or ruggedized flutes, silicone rubber. A recent development are "precision" pads fitted by a factory-trained technician. Over time, fish skin pads rot, and must be replaced. At least one author prefers silicone rubber pads, especially for students' flutes, because they do not rot or change dimension.
Pads were originally bedded in wax or lacquer, which prevented leaks and permitted them to migrate to a perfect closure. Modern pads are held by screws, which are far sturdier.
Many flutes use open-holed "french" pads so that the players' fingers can open the pad more quickly than the return spring permits. Many flute-players prefer these. Closed-pads permit a more relaxed hand position for some players, which can help their playing.
The pad return springs are phosphor bronze, and roughly the shape of a pin. Steel springs are mechanically superior, but are less electronegative than the silver or brass from which most flutes are constructed. The galvanic corrosion of salt and water from a player's breath and sweat will quickly cause steel springs to corrode to powder in a silver or nickel flute.
Flutes should have axles and pad-retaining screws of a compatible electronegative material, such as silver or phosphor bronze, rather than steel, but this is rare. As a result, most flutes' steel axles, screws and mechanisms need periodic cleaning and relubrication to clear out the corroded steel. It appears as a black or grey-blue powder mixed in the lubricant.
Playing a flute
A maladjusted flute is much more difficult to play, and beginning flute-players should invest in a professional adjustment if their instrument is not new. The most common problem as a flute ages is that its pads rot and leak. Also, rough handling can bend the pads and make them leak. The return springs can also weaken, causing slow or unsynchronized opening of the holes. Also, the pad-closure mechanisms can become misaligned or misadjusted. Occasionally the alignment pins can fall out.
Beginning players frequently find themselves unable to produce a sound. The most common reason is that the hole produced by their mouth is not aligned with the tone-hole. The standard beginning technique is to feel for the tone hole with one's tongue, and then roll the flute away to the correct angle.
Beginning flute players also often have improper emboucheres: The correct embouchere is a small elliptical or slot-like hole formed by the lips and directed at the edge of the tone-hole opposite the player. The aim should be more outward, with faster air for higher, or more brilliant sounds (more high-frequency overtones), and lower, more into the hole, with slower air for lower-notes. One reliable way to aim is to move one's chin in and out.
Correct breath control requires a player to emit large amounts of air, especially when the flute must play more loudly. A breathy sound is preferable to a pinched sound, because the breathy sounds to not carry, and a breathy tone is often otherwise louder and more pure.
Flutes often have the most rapidly changing parts in orchestral music. To become able to play these parts, one should practice complex scales in different modes and keys.
In outdoor playing, wind can "blow out" players' emboucheres, causing the air stream to become misplaced. It is normal practice for the piccolo and flute players of a marching band to face away from the wind in heavy weather; determining this action is customarily assigned to the flutes' section leader of the marching band.