Bores, Harmonics, and the Tone of the Clarinet (and other Woodwind Instruments)
Created | Updated Mar 18, 2003
In 1839, Hyacinthe Klose and August Buffet adapted the Boehm system used, at the time, on the flute to the clarinet. The resulting keywork system, after much refinement, is what is presently used throughout much of the clarinet-playing world. It is this 17-key system which every Buffet clarinet is now manufactured with.
The Boehm System
Buffet Crampon were founded in 1825 by Denis Buffet-Auger, a clarinet manufacturer in Paris, and the business has developed from this point, being praised at every point for the manufacture of outstanding clarinets, flutes, and saxophones. In 1839, the first clarinet with movable rings (the precursor to the Boehm system) was manufactured, and - to this end - a factory was built in 1850 in order to manufacture clarinets to this specification.
The Bore
In 1950, Robert Carée, a musician and acoustic technician, developed the bore still used in Buffet's R13 clarinet. The bore is the technical term for the space down the inside of the clarinet, which is, mostly, what produces the clarinet's distinctive sound. The clarinet is unusual in having a cylindrical bore: Most other woodwind instruments, including the oboe, flute, saxophone, and bassoon, have conical bores, enlarging towards the bottom of the instrument. Although the clarinet does flare out at the bottom of the instrument (in the lower joint and bell), the majority of the clarinet is, in fact, cylindrical.
Harmonics and Pressure
Compared to conical bore instruments, then, the clarinet's harmonics work in a distinctly different way. The clarinet, as a result of the cylindrical bore and one closed end, has a pressure minimum at the first open key, and a pressure maximum at the mouthpiece end.
Harmonics and Frequencies
When looking at the sound that instruments produce, it is usual to look at a graph of Amplitude / Time (milliseconds) in order to see a graphical representation of the sound as we hear it. A graph of this sort for the clarinet reveals that the even harmonics (or harmonics which are multiples of the fundamental frequency) are missing, and as a result, the clarinet has only the ODD harmonics.
Harmonics and Their Effect on Tone
When looking at a note, the fundamental frequency is the frequency on which the note is based: ie. a frequency, usually in Hz (Hertz) which, when played on its own, is at the pitch of the note. A concert 'A', for example, is exactly 440Hz. A concert A played on an electronic tuner, though, differs greatly from that of a trumpet. This in turn differs from that which might be sung, and so on. This is because the electronic tuner gives a 'pure' note, devoid of harmonics. The harmonics, however, are what give the note its tone. The clarinet, then, as a result of these different harmonics, sounds different from any other woodwind instrument.
Conical Bores and the Human Voice
The saxophone and oboe have conical bores, and therefore have the even harmonics in addition to the odd harmonics. This effect, felt due to the different bore of the clarinet, is what causes the unique tonality which the clarinet exhibits, and which is, in tonality and in range, the closest instrument to the human voice. (It is, maybe, for this reason that many composers such as Weber, who directed and wrote many operas, and Mozart, who is famous for his vocal work, wrote such a quantity of music for clarinet. Looking at Weber's work, there are many passages which resemble greatly operatic music, for example, the Recitativo at the end of the second movement of his second clarinet concerto, which is very much like an operatic aria and recitative).
Further Reading