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.
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.
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||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.
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:
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.
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.
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:
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.
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.
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.
Orchestras include a varying number of brass instruments depending on music style and era, typically:
British brass bands are made entirely up of brass, mostly conical bore instruments. Typical membership is:
quintets are common small brass ensembles, a quintet typically contains:
Big Bands and other jazz bands commonly contain cylindrical bore brass instruments
Concert bands have similar brass instrumentation to an orchestra, typically: