Clarinet, woodwind musical instrument, essentially a cylindrical-bore pipe sounded by a single beating reed that is clipped over a slot in a mouthpiece set in the upper end of the pipe. The lower end flares out into a bell. Modern clarinets typically are made of ebony (sometimes plastic) and have 20 or more side holes to produce different pitches; some are open, to be closed by the player's fingers, and others are covered by padded keys.
The most common size of clarinet, the B-flat soprano, has a range of about three-and-one-half octaves; the lowest note is the D (written E) below middle C. Notes above the lowest, or chalumeau, part of the range are obtained by depressing a speaker key and overblowing (increasing the speed of air blown into the instrument), which causes the instrument's air column to vibrate at a higher frequency. Being a cylindrical pipe stopped at one end, the clarinet overblows to the interval of a 12th above the fundamental pitch (unlike flutes and oboes, which overblow to the octave). Other common sizes of clarinet are the A soprano; the E-flat alto; the bass (an octave below the soprano); and the contrabass (an octave below the bass). The basset horn was a late-18th-century precursor of the alto clarinet. Music for all clarinets is written as if for a C clarinet; on a B-flat clarinet the written note C sounds as B-flat. Players can thus switch instruments without learning new fingerings. The term B-flat clarinet refers to the notation, and not to the acoustic fundamental note of the instrument.
The clarinet was invented about 1700 by the German flute maker Johann Christoph Denner as a modification of a folk reedpipe, the chalumeau. By about 1840 two complex systems of keywork had evolved: the Boehm system, used in most countries, and patented in 1844 by the French builder Auguste Buffet, who adapted the flute improvements of the German builder Theobald Boehm; and the narrower-bore, darker-sounding system developed about 1860 by the Belgian maker Eugène Albert.
Clarinets were common in orchestras by about 1780. Early works featuring the instrument include the overture for two clarinets and horn (1748) by the German-English composer George Frideric Handel and the clarinet concerto (1791) by Wolfgang Amadeus Mozart.
