The brass family consists of the trumpet, trombone, horn, euphonium (baritone) and tuba. They have a homogenous sound and blend well with one another. They provide a substantial amount of volume to the modern orchestra and are often used for their "brassy" timbre that is created at the loudest dynamics.
The modern brass family uses a combination of the overtone series and a descending chromatic valve system in order to play the notes in a scale. The overtone series (harmonics) are a mathematical function where shorter frequencies can be played in addition to the fundamental pitch.
The figure below demonstrates the first 15 partials of the harmonic series. There are several things to note:
- The higher the partial, the closer the interval
- Partials 8-15 can form a diatonic scale
- Notes with an X indicate pitches that are not in tune with the diatonic scale
- Partials 14 and above begin to form a chromatic scale
- Note the octaves: 1, 2, 4, 8, 16
Before the advent of valves, brass instruments relied on the upper partials to be able to play the notes of a scale. This is a practical reason for why baroque brass music is higher than the subsequent classical period. Beethoven used "baroque" trumpets in his pieces but rarely wrote above the 6th partial, while baroque composer Michael Haydn used the 18th partial.
Brass instruments consist of three major parts: the mouthpiece, the body, and the bell. Sound is created by the vibration of the lips. The body of the instrument controls the pitch. As valves are depressed, the length of the instrument is increased, lowering the pitch.
The timbre of the brass instrument is dictated by the shape of the bell. A conical system, such as the horn or cornet gradually increases in diameter, creating a more mellow timbre, while the cylindrical trumpet and trombone have a brighter timbre. The diameter does not increase until the bell.
Due to the nature of brass instruments, brass players benefit from rests. While playing, bloodflow to the lips is restricted by the mouthpiece. Higher pitches are generally more demanding of players and require more recovery time. It is common practice to use brass players less often than both the strings and woodwinds.
In addition, "chipping" notes is a possibility for brass players. A player may intend to play the 8th partial and instead play the 7th partial. The higher the partial, the greater likelihood for error, increasing with fatigue. A conservative composer will not begin phrases on higher partials (Jazz ignores this approach). In addition, writing large leaps in the brass can be risky, but rewarding.