Instruments that were played with mouthpieces that had a kind of simple reed were already known in Antiquity: a triangular section was cut out of the mouthpiece in such a way that the reed still hung on its end and could be controlled by the lips. The Egyptian memet from the 3rd century BC is one such early clarinet. It was played as a double instrument; the two cylindrical pipes were made of reeds or wood and tied together. They had fingerholes and two mouthpieces. These instruments were later adopted by the Greeks and Romans.

Clarinets with one, two and even three reeds were used in many cultures; indeed, in some parts of the world they are still in use and have remained unchanged (e.g., the Russian brelka or the Sardinian triple clarinet the launedda ).

In medieval Europe a single-reed instrument that had originated in the Orient and usually had eight fingerholes was common. This was the chalumeau. Chalumeau means “reed” and is derived from the Greek “calamos” and the Latin “calamus”. Chalumeaux had a range of about one octave (F4–G5). From the Renaissance onward they were made in various tunings, from treble to bass in keeping with the custom of the time.

In the late Middle Ages the term chalumeau (German: Schalmei, English: shawm) came to be used as a generic term for the whole shawm family.

Johann Christoph Denner (died 1707), an instrument maker from Nuremberg, is today generally credited with the invention of the clarinet, which evolved from the chalumeau toward the end of the 17th century. Exactly what Denner’s innovations were is not clear, which means that the exact difference in construction between the chalumeau and the clarinet, which coexisted for over half a century, is not known. What is generally accepted, however, is that Denner was the first to equip the chalumeau with two keys.

Following his example his son Jakob and other instrument makers of the time began producing clarinets with two keys and a wider bore. The chalumeau’s cylindrical bell was replaced by one that flared, and the clarinet tubing was given its characteristic barrel-shaped bulge (barrel) below the mouthpiece.

As on all baroque woodwind instruments the position of the hands had not yet been determined, so clarinets were made so that either hand could be in the lower position (for instance, a hole for the little finger was drilled on both the left and the right sides, the hole that was not needed was blocked up).

On the chalumeau only the fundamental register was played, in other words the pitches from the fundamental that could be produced using the fingerholes (the clarinet’s lowest register retains the name chalumeau to the present day). The sound is said to have been less than pleasant, having even been described as “wailing”. Initially only the upper register, the so-called clarinet register, was played on the clarinet. The high notes were produced by overblowing, the fingering remaining the same as in the fundamental scale. Overblowing was achieved with the aid of a speaker key on the reverse of the tubing (which was operated by the thumb) and was made easier by the small mouthpiece and narrow reed.

Because the clarinet overblows to the twelfth (octave + fifth) due to its cylindrical tubing, at least two keys were required to bridge the gap between the fundamental scale and the first overblown note.

Until the middle of the 18th century most clarinets had two keys: their lowest note was written F3. Pitches up to G4 were produced without keys, A4 with the front key, Bb4 by opening both keys. B4 was only rarely used and was produced by altering lip tension (using either the Bb4 or C5 fingering). B4 was not easily playable until a third key (B4 key) was added, which also extended the range downward to E3. The pitches from C5 upward (to about G6) were played by overblowing.

The clarinet’s timbre was originally hard and trumpet-like in the upper register, which not only earned it its name (little clarino or little trumpet) but also defined its initial role in the orchestra: the playing of trumpet-like parts in the upper register. By the end of the 18th century it had completely taken over from the previous incumbent of this position, the clarino (high trumpet). At the same time solo literature for the clarinet began to appear which was already exploiting the instrument’s great range and variety of timbre.

Like all woodwinds the clarinet suffered from the impure intonation and poor tonal quality of those notes played using cross-fingerings. The first attempts to solve this problem focused on the addition of keys. These early keys were prone to malfunction and most clarinetists rejected them as a merely temporary solution. Instead instrument makers began producing clarinets in many different tunings. Whereas baroque clarinets – like the natural trumpets of the period – were still being made chiefly in C and D, the second half of the 18th century saw the introduction of instruments in B, Bb, A, Ab and G so that several keys could be played while retaining evenness of timbre and purity of intonation.

This practice caused new problems, however. Aside from the fact that clarinetists now had to buy several instruments, switching between mouthpieces of varying size proved problematical for the embouchure and the change from an instrument that was already warmed up to a cold one posed new problems in terms of tuning. Although so-called “pièces de rechange”, components that could be exchanged, alleviated certain technical difficulties, they fell far short of solving the problem of inaccurate tuning.

Clarinet in D, Paris, France, 1830ies (Musikinstrumentenmuseum Schloss Kremsegg, Austria, Collection Streitwieser)

But although the construction of clarinets in various tunings did not solve the problem of intonation it did result in a wide choice of timbres which was greatly appreciated by musicians.

By the end of the 18th century instruments with five keys had become standard. The clarinet had established itself in the orchestra, in wind bands and in military bands. In the Classical period composers began to move away from clarinet concertos, in which the clarinet played mainly in the upper register, and made increasing use of the instrument’s lower notes (W. A. Mozart was a pioneer of this). In chamber and orchestral music the playing of broken chords in the chalumeau register as accompaniment to the melody became particularly popular.

From the second half of the 18th century a new awareness of the tonal qualities of the clarinet slowly emerged which blossomed in the age of sentimentalism. No longer was the clarinet sound seen as trumpet-like, hard, shrill and bright, but as the ideal vehicle for the expression of emotions. In his Ideen zur Ästhetik der Tonkunst (1784/85) Chr. Fr. D. Schubart had already described the clarinet’s timbre as “sweet”, “yearning” and “emotion melted in love”.

Clarinet in Eb, unsigned, probably by Conrad Eschenbach, Musikinstrumentenfabrik Markneukirchen, Saxony, founded 1883 (Musikinstrumentenmuseum Schloss Kremsegg, Austria, Collection Streitwieser)

At the turn of the century innovative instrument makers provided the clarinet with more keys.

The Frenchman J. X. Lefèvre added a sixth, a seventh was patented in 1800 by the Englishman James Wood and J. F. Simiot, another Frenchman, added a trill key and a small pipe to the G4 tone hole to prevent the escape of water.

In 1812 the German clarinetist Iwan Mueller presented a new model with thirteen keys, setting a milestone for all modern clarinet mechanics. His system was enthusiastically received by clarinetists and became the basis of imitation and improvement over the entire century.

In his key arrangement he took pains to ensure that all previous fingerings could be retained. He replaced the leather or felt key pads with skin pads filled with wool. Mueller was also an advocate of playing with the reed on the lower lip – up to that time playing reed uppermost had been widespread

In around 1840 parts of the keywork that Theobald Boehm had invented for the flute were transferred to the clarinet by the Parisian clarinetist Hyacinthe Eléonore Klosé (1808–1880) in collaboration with the instrument maker Louis-Auguste Buffet (died 1885). This “clarinette à anneaux mobiles” (“clarinet with movable rings”) served as the prototype of the so-called Boehm clarinet with seventeen keys which is nowadays widely used in Romance and Anglo-Saxon countries.

The Mueller clarinet was improved in Germany in around 1860 by Carl Baermann and Georg Ottensteiner (1815–1879). The 22-key Oehler clarinet, which was developed in 1900 by the instrument maker Oskar Oehler (1858–1936) and is now played in German-speaking countries, is a direct continuation of this development.

Because the clarinet’s modulatory capabilities made it especially well suited to the sound ideal of the Romantic period it became the most important wind instrument in the Romantic orchestra in the 19th century along with the horn (since Beethoven it has been customary to use two). The Bb clarinet became standard, with the A and C clarinets also in use, although the latter is only very seldom called for today on account of its characteristic timbre (e.g., in the “witches’ sabbath” movement in Hector Berlioz’s Symphonie fantastique).

In military, popular and jazz music only the Bb clarinet is widespread. In jazz, which gave the orchestral clarinet modern techniques such as glissando to play, the clarinet was often used as a melody instrument but was replaced more and more by the saxophone. In the USA jazz clarinetists traditionally double on other woodwind instruments in the same register as their own. In the production of musicals several reeds often share a part.