The bassoon is the tenor member of the woodwind family. Like the oboe it has a double reed and overblows an octave higher. It is considered to have a tone color similar to that of the human voice, particularly in the central and upper register. The bassoon is around 5 to 8 feet long, depending on the model and type.
Playing it is facilitated by doubling the tube back on itself and by closing the distance between the widely-spaced holes with a complex system of keywork. It disassembles into five main pieces: the bell, extending upward; the bass (or long) joint, connecting the bell and the boot; the boot (or butt), at the bottom of the instrument and folding over on itself; the wing joint, which extends from boot to bocal; and the bocal (or crook), a crooked metal tube which attaches wing joint to reed.
The instrument is played either by a seated player sitting on a strap attached to the bottom of the instrument, or is held with a neck strap. The instrument, in either case, extends diagonally across the player's body, a bit like a saxophone.
The range of the bassoon begins at B-flat1 (the first one below the bass staff) and extends upward over three octaves (roughly to the E on the treble staff). Higher notes are possible but difficult to produce and rarely called for; orchestral parts rarely go higher than the C or D, with even Stravinsky's famously difficult opening solo in The Rite of Spring only ascending to the D. Low A at the bottom of the range is possible with a special extension to the instrument; as its use makes the bottom B-flat impossible to play and affects the intonation of the lower notes, it is rarely called for. The Quintet for Winds by Carl Nielsen concludes with a featured use of the low A. Bassoon music is written in bass clef, untransposed, while the tenor clef is frequently used for the high register and, in rare cases, the treble clef. Its closest relative, the contrabassoon (or double bassoon), sounds an octave lower. The bassoon overblows at the octave (above F on the bass clef) with the aid of a "whisper key" (a kind of reverse octave key) that opens in the higher registers.
The double reed used is 53-58 mm in total length, and made of Arundo donax cane. The bassoon (and contrabassoon) are alone in the woodwind family in that they are both fingered with Heckel-system keywork, a descendant of the original Baroque fingering system, as opposed to the otherwise ubiquitous Boehm system. An alternate, unrelated, fingering system is used in France, but in the U.S. and most of Europe the Heckel system is dominant.