The euphonium is a medium-sized, 3 or 4-valve, often compensating, conical-bore, tenor-voiced brass instrument that derives its name from the Ancient Greek word εὔφωνος euphōnos, meaning "well-sounding" or "sweet-voiced". The euphonium is a valved instrument. Nearly all current models have piston valves, though some models with rotary valves do exist.
Music notation or musical notation is any system used to visually represent aurally perceived music played with instruments or sung by the human voice through the use of written, printed, or otherwise-produced symbols, including notation for durations of absence of sound such as rests.
The pitch of a brass instrument corresponds to the lowest playable resonance frequency of the open instrument. The combined resonances resemble a harmonic series. The fundamental frequency of the harmonic series can be varied by adjusting the length of the tubing using the instrument's valve, slide, key or crook system, while the player's embouchure, lip tension and air flow serve to select a specific harmonic from the available series for playing. The fundamental is essentially missing from the resonances and is impractical to play on most brass instruments, but the overtones account for most pitches.
The saxhorn is a family of valved brass instruments that have conical bores and deep cup-shaped mouthpieces. The saxhorn family was developed by Adolphe Sax, who is also known for creating the saxophone family. The sound of the saxhorn has a characteristic mellow tone quality and blends well with other brass.
The trombone is a musical instrument in the brass family. As with all brass instruments, sound is produced when the player's vibrating lips cause the air column inside the instrument to vibrate. Nearly all trombones use a telescoping slide mechanism to alter the pitch instead of the valves used by other brass instruments. The valve trombone is an exception, using three valves similar to those on a trumpet, and the superbone has valves and a slide.
A clef is a musical symbol used to indicate which notes are represented by the lines and spaces on a musical stave. Placing a clef on a stave assigns a particular pitch to one of the five lines, which defines the pitches on the remaining lines and spaces.
C or Do is the first note and semitone of the C major scale, the third note of the A minor scale, and the fourth note of the Guidonian hand, commonly pitched around 261.63 Hz. The actual frequency has depended on historical pitch standards, and for transposing instruments a distinction is made between written and sounding or concert pitch. It has enharmonic equivalents of B♯ and D.
In Western musical notation, the staff or stave (UK) is a set of five horizontal lines and four spaces that each represent a different musical pitch or in the case of a percussion staff, different percussion instruments. Appropriate music symbols, depending on the intended effect, are placed on the staff according to their corresponding pitch or function. Musical notes are placed by pitch, percussion notes are placed by instrument, and rests and other symbols are placed by convention.
A transposing instrument is a musical instrument for which music notation is not written at concert pitch. For example, playing a written middle C on a transposing instrument produces a pitch other than middle C; that sounding pitch identifies the interval of transposition when describing the instrument. Playing a written C on clarinet or soprano saxophone produces a concert B♭, so these are referred to as B♭ instruments. Providing transposed music for these instruments is a convention of musical notation. The instruments do not transpose the music; rather, their music is written at a transposed pitch. Where chords are indicated for improvisation they are also written in the appropriate transposed form.
The baritone horn, or sometimes just called baritone, is a low-pitched brass instrument in the saxhorn family. It is a piston-valve brass instrument with a bore that is mostly conical but it has a narrower bore compared to the similarly pitched euphonium. It uses a wide-rimmed cup mouthpiece like that of its peers, the trombone and euphonium. Like the trombone and the euphonium, the baritone horn can be considered either a transposing or non-transposing instrument.
The tenor horn is a brass instrument in the saxhorn family and is usually pitched in E♭. It has a bore that is mostly conical, like the flugelhorn and euphonium, and normally uses a deep, cornet-like mouthpiece.
The bass clarinet is a musical instrument of the clarinet family. Like the more common soprano B♭ clarinet, it is usually pitched in B♭, but it plays notes an octave below the soprano B♭ clarinet. Bass clarinets in other keys, notably C and A, also exist, but are very rare. Bass clarinets regularly perform in orchestras, wind ensembles and concert bands, and occasionally in marching bands, and play an occasional solo role in contemporary music and jazz in particular.
Braille music is a braille code that allows music to be notated using braille cells so music can be read by visually impaired musicians. The system was incepted by Louis Braille.
SATB is an initialism that describes the scoring of compositions for choirs, and also choirs of instruments. The initials are for the voice types: S for soprano, A for alto, T for tenor and B for bass.
The alto trombone is the alto member of the trombone family of brass instruments, smaller than the tenor trombone. It is almost always pitched in E♭ a fourth higher than the tenor, although examples pitched in F are occasionally found. The alto trombone was commonly used from the 16th to the 18th centuries in church music to strengthen the alto voice, particularly in the Mass. Alto trombone parts are usually notated in alto clef.
Advanced Placement (AP) Music Theory is a course and examination offered in the United States by the College Board as part of the Advanced Placement Program to high school students who wish to earn credit for a college level music theory course.
Percussion notation is a type of musical notation indicating notes to be played by percussion instruments. As with other forms of musical notation, sounds are represented by symbols which are usually written onto a musical staff.
Chiavette is a system of standard combinations of clefs used in polyphonic music of the 16th through 18th centuries, differing from the usual chiavi naturali Typically, these clefs place each staff line a third lower than usual.
or whole rest 
where there are multiple voices on one staff and such a rest is forced above or below the staff. (The rare double whole rest is suspended between two ledger lines in this situation.)
