Page 5 - Info Magazine nr 14 december 2020

The change of register on the clarinet

author: Cécile Rongen
The clarinet is a graceful instrument for children and young people: once you realize how to keep
the embouchure, sound almost always comes out immediately, at least in the chalumeau regis-
ter - the low register that you can play
without using the register key or ‘duo-
decime key’. The predecessor of the cla-
rinet, the chalumeau, did not have this
key. But because Denner added it to the
chalumeau around 1700, from then on,
a much wider range of tones and regis-
ters became available. The clarinet even
owes its name to that high clarinet/clari-
on register, which resembled the sound
of a trumpet, called "clarineo", in Italian.

In practice, switching to the high register is a challenge for many. What exactly is the problem?
Clarinet teachers will probably recognize it: your pupil plays a nice tune in the chalumeau register
and at a certain moment is ready for the clarion/middle register. The use of the register key is the
next step. But why is it often so difficult to get sound out of the clarinet in the second register?
And why is the clarinet the only woodwind instrument with which does not sound an octave but a
twelfth higher, when you use the register key? Because it is (for the most part) a cylindrical tube,
which is closed on one side, namely at the mouthpiece. A clarinet therefore behaves like a closed
organ pipe. When you go to the next register with such a closed pipe, the air vibrates three times
as fast. An example: if you play a sounding low E, the air vibrates 165 times per second (165 Hertz).
If you go to the second register, the air vibrates three times
faster. If you calculate that, you come to 495 Hertz, and that
sounds like a high B. Flutes, oboes and saxophones do not
behave like a closed organ pipe, because they do not have a
cylindrical but a conical tube. When you go to the next regis-
ter with those instruments, the air vibrates not three times,
but twice as fast: that makes the tone one octave higher.

(Nice to know: closed organ pipes sound a lot lower than you would ex-
pect in relation to their length. For instance, a clarinet sounds almost an
octave lower than a soprano saxophone, a flute and an oboe, while those
instruments are almost the same length.)
The principle from the organ pipe example is clear: the clarinet can only sound when air is blown
through the pipe; from a low E to a B-flat (index finger and thumb left hand). From the tone that
follows, the "long B" (all holes and 1 or 2 little fingers keys closed) we actually play overtones. Try
blowing over the notes without the register key: the low E becomes a middle B, the low F a middle
C, etc. The register key is merely an aid to make it easier to blow over these overtones.
Copper wind instruments such as trumpets and horns do not have a register key; they have to pro-
duce overtones with a change of embouchure and especially air velocity. For clarinet players, air
velocity does not seem to be an issue, because the register key helps us; but the opposite is true!
Even clarinettists need to give more air velocity to play overtones (all tones from the "long B").
This principle can only work if the basic elements of clarinet playing are in control. In the order of
priority these are: relaxation, breath support/airflow and embouchure.