Brass instrument
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. Brass instruments are also called labrosones[1] or labrophones, from Latin and Greek elements meaning 'lip' and 'sound'.
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.
Sound production in brass instruments[edit]
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 vibrates. 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).
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.
Manufacture[edit]
Metal[edit]
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.
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 aluminium 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.
The process of making the large open end (bell) of a brass instrument is called metal beating. In making the bell of, for example, a trumpet, a person lays out a pattern and shapes sheet metal into a bell-shape using templates, machine tools, handtools, and blueprints. The maker cuts out the bell blank, using hand or power shears. He hammers the blank over a bell-shaped mandrel, and butts the seam, using a notching tool. The seam is brazed, using a torch and smoothed using a hammer or file. A draw bench or arbor press equipped with expandable lead plug is used to shape and smooth the bell and bell neck over a mandrel. A lathe is used to spin the bell head and to form a bead at the edge of bell head. Previously shaped bell necks are annealed, using a hand torch to soften the metal for further bending. Scratches are removed from the bell using abrasive-coated cloth.
Brass instruments are one of the major classical instrument families and are played across a range of musical ensembles.
Orchestras include a varying number of brass instruments depending on music style and era, typically:
Concert bands generally have a larger brass section than an orchestra, typically:
British brass bands are made up entirely 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.
Mexican bandas have:
Single brass instruments are also often used to accompany other instruments or ensembles such as an organ or a choir.