A brass instrument is a musical instrument that produces sound by sympathetic vibration of air in a tubular resonator in sympathy with the vibration of the player's lips. The term labrosone, from Latin elements meaning "lip" and "sound", is also used for the group, since instruments employing this "lip reed" method of sound production can be made from other materials like wood or animal horn, particularly early or traditional instruments such as the cornett, alphorn or shofar.
There are several factors involved in producing different pitches on a brass instrument. Slides, valves, crooks (though they are rarely used today), or keys are used to change vibratory length of tubing, thus changing the available harmonic series, while the player's embouchure, lip tension and air flow serve to select the specific harmonic produced from the available series.
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 one finds brass instruments made of wood, like the alphorn, the cornett, the serpent and the didgeridoo, while some woodwind instruments are made of brass, like the saxophone.
Families 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, or crooks, into the instrument, changing its overall length. This family includes all of the modern brass instruments except the trombone: the trumpet, horn (also called French horn), euphonium, and tuba, as well as the cornet, flugelhorn, tenor horn (alto horn), baritone horn, sousaphone, and the mellophone. 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; the latter are the norm for the horn (except in France) and are also common 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 pieces. In more modern compositions, they are occasionally used for their intonation or tone color. Natural brass instruments only play notes in the instrument's harmonic series. These 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. In the 18th century, makers developed interchangeable crooks of different lengths, which let players use a single instrument in more than one key. 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, keyed bugle and keyed trumpet. They are more difficult to play than valved instruments.
Bore taper and diameter Brass instruments may also be characterised by two generalizations about geometry of the bore, that is, the tubing between the mouthpiece and the flaring of the tubing into the bell. Those two generalizations are with regard to the degree of taper or conicity of the bore and the diameter of the bore with respect to its length.
Cylindrical vs. conical bore While all modern valved and slide brass instruments consist in part of conical and in part of cylindrical tubing, they are divided as follows: Cylindrical bore brass instruments are those in which approximately constant diameter tubing predominates. Cylindrical bore brass instruments are generally perceived as having a brighter, more penetrating tone quality compared to conical bore brass instruments. The trumpet, and all trombones are cylindrical bore. In particular, the slide design of the trombone necessitates this. Conical bore brass instruments are those in which tubing of constantly increasing diameter predominates. Conical bore instruments are generally perceived as having a more mellow tone quality than the cylindrical bore brass instruments. The "British brass band" group of instruments fall into this category. This includes the flugelhorn, cornet, tenor horn (alto horn), baritone horn, horn, euphonium and tuba. Some conical bore brass instruments are more conical than others. For example, the flugelhorn differs from the cornet by having a higher percentage of its tubing length conical than does the cornet, in addition to possessing a wider bore than the cornet. In the 1910s and 1920s, the E. A. Couturier company built brass band instruments utilizing a patent for a continuous conical bore without cylindrical portions even for the valves or tuning slide.
Whole-tube vs. half-tube The resonances of a brass instrument resemble a harmonic series, with the exception of the lowest resonance, which is significantly lower than the fundamental frequency of the series that the other resonances are overtones of. Depending on the instrument and the skill of the player, the missing fundamental of the series can still be played as a pedal tone, which relies mainly on vibration at the overtone frequencies to produce the fundamental pitch. The bore diameter in relation to length determines whether the fundamental tone or the first overtone is the lowest partial practically available to the player in terms of playability and musicality, dividing brass instruments into whole-tube and half-tube instruments. These terms stem from a comparison to organ pipes, which produce the same pitch as the fundamental pedal tone of a brass instrument of equal length.
Whole-tube instruments have larger bores in relation to tubing length, and can play the fundamental tone with ease and precision. The tuba and euphonium are examples of whole-tube brass instruments. Half-tube instruments have smaller bores in relation to tubing length and cannot easily or accurately play the fundamental tone. The second partial (first overtone) is the lowest note of each tubing length practical to play on half-tube instruments. The trumpet and horn are examples of half-tube brass instruments.
Other brass instruments The instruments in this list fall for various reasons outside the scope of much of the discussion above regarding families of brass instruments. Alphorn (wood) Conch (shell) Didgeridoo (wood, Australia) Natural horn (no valves or slides—except tuning crooks in some cases) Jazzophone Keyed bugle (keyed brass) Keyed trumpet (keyed brass) Saxhorn Serpent (keyed brass) Ophicleide (keyed brass) Shofar (animal horn) Vladimirskiy rozhok (wood, Russia) Vuvuzela (simple short horn, origins disputed but achieved fame or notoriety through many plastic examples in the 2010 World Cup) Lur
Valves
Valves are used to change the length of tubing of a brass instrument allowing the player to reach the notes of various harmonic series. Each valve pressed diverts the air stream through additional tubing, individually or in conjunction with other valves. This lengthens the vibrating air column thus lowering the fundamental tone and associated harmonic series produced by the instrument. Designs exist, although rare, in which this behaviour is reversed, i.e., pressing a valve removes a length of tubing rather than adding one. One modern example of such an ascending valve is the Yamaha YSL-350C trombone, in which the extra valve tubing is normally engaged to pitch the instrument in B, and pressing the thumb lever removes a whole step to pitch the instrument in C. Valves require regular lubrication.
A core standard valve layout based on the action of three valves had become almost universal by (at latest) 1864 as witnessed by Arban's method published in that year. The effect of a particular combination of valves may be seen in the table below. This table is correct for the core three-valve layout on almost any modern valved brass instrument. The most common four-valve layout is a superset of the well-established three-valve layout and is noted in the table, despite the exposition of four-valve and also five-valve systems (the latter used on the tuba) being incomplete in this article.
+ Valve combination and effect on pitchValve combination Effect on pitch Interval Tuning problems2 step Minor second 1 1 step Major second 1+2 or 3 step Minor third Very slightly sharp2+3 2 steps Major third Slightly sharp1+3 or 4 steps Perfect fourth Sharp (1+3 only)1+2+3 or 2+4 3 steps Tritone Very sharp (1+2+3 only)1+4 steps Perfect fifth 1+2+4 or 3+4 4 steps Augmented fifth Flat2+3+4 steps Major sixth Slightly sharp1+3+4 5 steps Minor seventh Sharp1+2+3+4 steps Major seventh Very sharp
Tuning Since valves lower the pitch, a valve that makes a pitch too low (flat) creates an interval wider than desired, while a valve that plays sharp creates an interval narrower than desired. Intonation deficiencies of brass instruments that are independent of the tuning or temperament system are inherent in the physics of the most popular valve design, which uses a small number of valves in combination to avoid redundant and heavy lengths of tubingUnderstanding Brass Instrument Intonation, University of Oklahoma Horn Studio (this is entirely separate from the slight deficiencies between Western music's dominant equal (even) temperament system and the just (not equal) temperament of the harmonic series itself). Since each lengthening of the tubing has an inversely proportional effect on pitch (pitch of brass instruments), while pitch perception is logarithmic, there is no way for a simple, uncompensated addition of length to be correct in every combination when compared with the pitches of the open tubing and the other valves.
Absolute tube length For example, given a length of tubing equaling 100 units of length when open, one may obtain the following tuning discrepancies:
+ Valve combination and creation of pitch discrepanciesValve(s) Desired pitch Necessary valve length Component tubing length Difference Slide positionsOpen tubing A/B 0 – – 12 A 5.9 – – 21 G/A 12.2 – – 31+2 or 3 G 18.9 18.1 0.8 42+3 F/G 25.9 24.8 1.1 51+3 or 4 F 33.5 31.1 2.4 6 or T1+2+3 or 2+4 E 41.4 37 4.4 7 or T+21+4 D/E – 45.7 – T+31+2+4 or 3+4 D – 52.4 – T+42+3+4 C/D – 58.3 – T+51+3+4 C – 64.6 – T+61+2+3+4 B – 70.5 – T+7
Playing notes using valves (notably 1st + 3rd and 1st + 2nd + 3rd) requires compensation to adjust the tuning appropriately, either by the player's lip-and-breath control, via mechanical assistance of some sort, or, in the case of horns, by the position of the stopping hand in the bell. 'T' stands for trigger on a trombone.
Relative tube length
Traditionally, the valves lower the pitch of the instrument by adding extra lengths of tubing based on just intonation: 1st valve: of main tube, making an interval of 9:8, a pythagorean major second 2nd valve: of main tube, making an interval of 16:15, a just minor second 3rd valve: of main tube, making an interval of 6:5, a just minor third
Combining the valves and the harmonics of the instrument leads to the following ratios and comparisons to 12-tone equal tuning and to a common five-limit tuning in C: