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Brass instrument

A brass instrument is a musical instrument whose tone is produced by vibration of the lips as the player blows into a tubular resonator. They are also called labrosones, literally meaning "lip-vibrated instruments" (Baines, 1993).

There are two factors in changing the pitch on a valved brass instrument: pressing the valves to change the length of the tubing, and changing the player's lip aperture or "embouchure", which determines the frequency of the vibration into the instrument.

The view of most scholars (see organology) is that the term "brass instrument" should be defined by the way the sound is made, as above, and not by whether the instrument is actually made of brass. Thus, as exceptional cases one finds brass instruments made of wood like the alphorn, the cornett, and the serpent, while some woodwind instruments are made of brass, like the saxophone.

Families of brass instruments

Modern brass instruments generally come in one of two families:

Valved brass instruments use a set of valves (typically three or four but as many as seven or more in some cases) operated by the player's fingers that introduce additional tubing into the instrument, changing its overall length. This family includes all of the modern brass instruments except the trombone: the trumpet, horn (also called the French horn), euphonium, and tuba, as well as the cornet, flügelhorn, baritone horn, sousaphone, mellophone, and the old saxhorn. As valved instruments are predominant among the brasses today, a more thorough discussion of their workings can be found below. The valves are usually piston valves, but can be rotary valves. Rotary valves are the norm for the horn and are also prevalent on the tuba.

Slide brass instruments use a slide to change the length of tubing. The main instruments in this category are the trombone family, though valve trombones are occasionally used, especially in jazz. The trombone family's ancestor the sackbut and the folk instrument bazooka are also in the slide family.

There are two other families that have, in general, become functionally obsolete for practical purposes. Instruments of both types, however, are sometimes used for period-instrument performances of Baroque- or Classical-era pieces. In more modern compositions, they are occasionally used for their intonation or tone color.

Natural brass instruments, on which only notes in the instrument's harmonic series are available. Such instruments include the bugle and older variants of the trumpet and horn. The trumpet was a natural brass instrument prior to about 1795, and the horn before about 1820. Natural instruments are still played for period performances and some ceremonial functions, and are occasionally found in more modern scores, such as those by Richard Wagner and Richard Strauss.

Keyed or Fingered brass instruments used holes along the body of the instrument, which were covered by fingers or by finger-operated pads (keys) in a similar way to a woodwind instrument. These included the cornett, serpent, ophicleide and keyed trumpet. They are more difficult to play than valved instruments.

Brass instruments may also be characterised by the geometry of the tubing, the bore. Definition of bore is not clear cut, as with woodwind instruments, due to brass instruments' bell.

Cylindrical bore with approximately constant diameter tubing; cylindrical bore instruments have a bright projected tone. The trumpet, alto trombone and tenor trombone are cylindrical bore - the slide design of the trombone necessitates this.

Conical bore with constantly increasing diameter tubing; conical bore instruments have a mellow tone. The "British brass band" group of instruments fall into this category. This includes the cornet, tenor horn (alto horn), French horn, baritone, euphonium and tuba.

Some other wind instruments

Valves

Valves are used to change the length of tubing of a brass instrument allowing the musician to change pitch. When pressed each valve changes the pitch by diverting the air stream through additional tubing, thus lengthening the instrument and lowering the harmonic series on which the instrument is vibrating. It is possible, although rare, for this behaviour to be reversed, i.e., pressing the valve removes a length of tubing rather than adding one).

Valves are employed in combination to play different notes; a single standard had become almost universal. A particular combination of valves has an effect on pitch from any given harmonic, the effect may be seen below. This table is correct for almost any modern brass instrument.

Valve combination and effect on pitch on a given harmonic.
Valve combination	Effect on harmonic	Interval	Tuning problems
Second	1/2 step	Minor second
First	1 step	Major second
First and second	1 1/2 step	Minor third
Third	1 1/2 step	Minor third	Flat
Second and third	2 steps	Major third
First and third	2 1/2 steps	Perfect fourth	Sharp
First second and third	3 steps	Tritone	Very sharp

The tuning of brass instruments is not perfect, the mentioned tuning deficiencies are unavoidable; they are inherent in the construction of the instrument. Playing notes using certain combinations of valves requires "compensation" to adjust the tuning appropriately.

Valve tuning compensation

The additional tubing for each valve usually features a short tuning slide of its own for fine adjustment of the valve's tuning, except when it is too short to make this practicable. For the first and third valves this is often designed to be adjusted as the instrument is played, to account for the deficiencies in the valve system.

In most trumpets and cornets, the compensation must be provided by extending the third valve slide with the fourth finger, and the first valve slide with the left hand thumb, see "triggers and throws" below. This is used to lower the pitch of the 1-3 and 1-2-3 valve combinations. On the trumpet and cornet, these valve combinations correspond to low D, low C, low G, and low F, so chromatically, to stay in tune, one must use this method.

In instruments with a fourth valve, such as tubas, euphoniums, and piccolo trumpets, that valve lowers the pitch by a perfect fourth; this is used to compensate for the sharpness of the valve combinations 1-3 and 1-2-3 (4 replaces 1-3, 2-4 replaces 1-2-3). All three normal valves may be used in addition to the fourth to increase the instrument's range downwards by a perfect fourth, although with increasingly severe intonation problems.

When four-valved models without any kind of compensation play in the corresponding register, the sharpness becomes so severe that players must finger the note a half-step below the one they are trying to play. This eliminates the note a half-step above their open fundamental.

Manufacturers of low brass instruments may choose one or a combination of four basic approaches to compensate for the tuning difficulties, whose respective merits are subject to debate:

Compensation system

In the Compensation system, each of the first two (or three) valves has an additional set of tubing extending from the back of the valve. When the third (or fourth) valve is depressed in combination with another one, the air is routed through both the usual set of tubing plus the extra one, so that the pitch is lowered by an appropriate amount. This allows compensating instruments to play with accurate intonation in the octave below their open second partial, which is critical for tubas and euphoniums in much of their repertoire.

The compensating system was applied to French horns to serve a different purpose. It was used to allow a double horn in F and B flat to ease playing difficulties in the high register. In contrast to the system in use in tubas and euphoniums, the default 'side' of the horn is the longer F horn, with secondary lengths of tubing in coming into play when the first, second or third valves are pressed; pressing the thumb valve takes these secondary valve slides and the extra length of main tubing out of play to produce a shorter B-flat horn. A later "full double" design has completely separate valve section tubing for the two sides, and is considered superior, although rather heavier in weight.

Additional valves

Initially, compensated instruments tended to sound stuffy and blow less freely due to the air being doubled back through the main valves. In early designs, this led to sharp bends in the tubing and other obstructions of the air-flow. Some manufacturers therefore preferred adding more 'straight' valves instead, which for example could be pitched a little lower than the 2nd and 1st valves and were intended to be used instead of these in the respective valve combinations. While no longer featured in euphoniums for decades, professional tubas are still built like this, with five valves being the norm on CC- and BB-tubas and five or six valves on F-tubas.

Compensating double French horns can also suffer from the stuffiness resulting from the air being passed through the valve section twice, but as this really only affects the longer F side, a compensating double can be very useful for a 1st or 3rd horn player, who uses the F side less.

Additional sets of slides on each valve

Another approach was the addition of two sets of slides for different parts of the range. There used to be euphoniums and tubas built like this, but today, this approach has become highly exotic for all instruments - except French horns for which it is the norm, usually in a double, sometimes even triple configuration.

Trigger or Throw

Triggers or throws are sometimes provided on valved brass instruments allow manual, temporary, lengthening of the main tuning slide or a valve slide. These mechanisms are used to lower the pitch of notes that are naturally sharp in a specific register of the instrument, and are designed for speedy adjustment whilst playing.

A trigger is a mechanical lever that lengthens a slide when pressed in a contrary direction. Triggers are sprung in such a way to that they return the slide to its original position when released.

A throw is a simple metal grip for the player's finger or thumb, attached to a valve slide. The general term "throw" can be used to describe a u-hook, a saddle (u-shaped grips), or a ring (ring-shape grip) in which a player's finger or thumb rests. A player extends their finger or thumb to lengthen a slide, and retracts their finger to return the slide to its original position.

Some examples of instruments that utilize triggers or throws are:

Trumpet or Cornet

Triggers or throws are sometimes found on the first valve slide. They are operated by the player's thumb and are used to adjust the higher F, D and B.

Triggers or throws are often found on the third valve slide. They are operated by the player's fourth finger, and are used to adjust the lower D, C A, G, and F. Trumpets typically use throws, whilst cornets may have a throw or trigger.

Euphoniums

A euphonium occasionally has a trigger on valves other than 2 (especially 3).

Valve mechanism

The two major types of valves are rotary valves and piston valves. The first piston valve instruments were developed just after the start of the 19th century. The Stölzel valve (invented by Heinrich Stölzel in 1814) was an early variety. In the mid 19th century the Vienna valve was an improved design. However most professional musicians preferred rotary valves for quicker, more reliable action, until better designs of piston valves were mass manufactured towards the end of the 19th century. Since the early decades of the 20th century, piston valves have been the most common on brass instruments.

Sound production in brass instruments

Because the player of a brass instrument has direct control of the prime vibrator (the lips), brass instruments exploit the player's ability to select the harmonic at which the instrument's column of air will vibrate. By making the instrument about twice as long as the equivalent woodwind instrument and starting with the second harmonic, players can get a good range of notes simply by varying the tension of their lips (see embouchure). Brass players call each harmonic a "partial" because each loop of the vibrating air column only occupies part of the tubing (whereas at the fundamental, the loop occupies the entire length of tubing).

Most brass instruments are fitted with a removable mouthpiece. Different shapes, sizes and styles of mouthpiece may be used to suit different embouchures, or to more easily produce certain tonal characteristics. Trumpets, trombones, and tubas are characteristically fitted with a cupped mouthpiece, while horns are fitted with a conical mouthpiece.

One interesting difference between a woodwind instrument and a brass instrument is that woodwind instruments are non-directional. This means that the sound produced propagates in all directions with approximately equal volume. Brass instruments, on the other hand, are highly directional, with most of the sound produced traveling straight outward from the bell. This difference makes it significantly more difficult to record a brass instrument accurately. It also plays a major role in some performance situations, such as in marching bands.

Materials

Brass instruments are made of a lacquered or plated metal. Traditionally the instruments are normally made of brass, polished and then lacquered to prevent corrosion. Some higher quality and higher cost instruments use gold or silver plating to prevent corrosion. A few specialty instruments are made from wood.

Alternatives to brass include other alloys containing significant amounts of copper or silver. These alloys are biostatic due to the oligodynamic effect, and thus suppress growth of molds, fungi or bacteria. Brass instruments constructed from stainless steel or aluminum have good sound quality but are rapidly colonized by microorganisms and become unpleasant to play.

Most higher quality instruments are designed to prevent or reduce galvanic corrosion between any steel in the valves and springs, and the brass of the tubing. This may take the form of desiccant design, to keep the valves dry, sacrificial zincs, replaceable valve cores and springs, plastic insulating washers, or nonconductive or noble materials for the valve cores and springs. Some instruments use several such features.

Didactics

Children may start to learn a brass instrument as soon as all their permanent teeth have arrived, usually at age 11. It is possible to start earlier, but while the teeth are still changing, the embouchure will need occasional adjustment, and pressure on the lips and teeth may have undesirable effects.

Ensembles

Brass instruments are one of the major classical instrument families and are played across a range of ensembles.

Orchestras include a varying number of brass instruments depending on music style and era, typically:

Classical symphony orchestra:

*two to five trumpets

*two to eight french horns

*two tenor trombones

*one bass trombone

*one tuba

Baroque orchestras may include valveless trumpets or bugles, or trumpets/cornets playing these parts.
Romantic and modern orchestras may include larger numbers of brass including more exotic instruments.

British brass bands are made entirely up of brass, mostly conical bore instruments. Typical membership is: