Clarinets have been around for a very time, although they did not look at first the way they do today. The history of the clarinet goes as far back as the late 1600′s, when an instrument known as a chalumeau was in occasional use in orchestras. The chalumeau is commonly considered to be a forerunner of our modern clarinet, although it bore little resemblance to the ones we play today.
The chalumeau was a cane pipe measuring about 20cm (about 9 inches) long. It had seven holes, including a thumb hole, and a range of not much more than an octave. The name chalumeau suggests a French origin for this little instrument. But it was Johann Denner, a leading German woodwind maker, who was credited with improving it, and in doing so inventing the early clarinet. Sometime around 1700, Denner added two keys to the chalumeau, expanding its range by giving it an upper register. He also may have given it a separate mouthpiece and reed.
The history of the clarinet continued to develop as two-keyed clarinets underwent a variety of improvements and were introduced to France and England. By about 1750, the clarinet body had taken the basic shape we see today, but the keywork continued to evolve. In about 1780, five keys were being used. And by 1820 or 1830, clarinets were commonly in use that had 12 or 13 keys. By 1850 or so Boehm system keywork had been introduced. This system, based on the keywork then being used on the flute, managed to eliminated some very difficult fingerings. It is the system most commonly used today although Albert fingering systems are also still in use, primarily in Europe. In North America, it is rare to see a clarinet that does not use Boehm keywork.
In the mid to late 1700′s, composers had begun writing musical pieces that included, or were specifically written for, clarinets. The instrument became much more prominent in the 1800′s, and large volumes of music were written for it in the early 1900′s.
Today, there are minor variations in different models. Manufacturers use slightly different bore diameters and shapes, and occasionally additional keys. Most modern clarinets have 17 or 18 keys.