Klarinet Archive - Posting 000209.txt from 1995/02

From: Jonathan Cohler <cohler@-----.NET>
Subj: Re: Caution, More Physics!
Date: Thu, 9 Feb 1995 16:26:01 -0500

>Jonathan,
> You say that our pitch goes flat as we blow harder because our upper
>harmonic content increases. This assumes, I infer, that upper harmonics in
>the clarinet's tonal spectrum are flat by nature. As we climb to higher
>registers, higher partials become fundamentals. [first in the chalumeau and
>throat, third in the clarion, fifth for c'''# through open f'''#, etc.] If
>this is true, why do so many clarinets play sharp in the altissimo register?
>Is it the fingerings we use, or lip pressure, or what?
>
>David Gilman

We modify fingerings as we go up into the altissimo, precisely because they
are so out of tune. For example, finger a low A (I'll call it A1). The
first partial of this is a flat E3 which you can generate without the
octave key by raising your tongue closer to the roof of your mouth. If you
play the E3 partial while fingering A1 (no octave key), you will hear that
it is slightly flat.

Now add the octave key. That makes it easier to speak and brings it up
into pitch (in fact, on the Buffet, both the A1 and E3 are sharp).

The next harmonic is the C#3. You can also make this note sound while
fingering A1. Again raise the tongue, and possibly push your jaw slightly
forward. It will be even flatter than E3 was. Adding the octave key makes
it slightly sharper, and lifting the first finger of your left hand finally
brings it up to pitch.

All of the altissimo fingerings are modified from the "natural" fingering
to bring them in tune. Not all fingerings are sharp by any means. In
fact, on a Buffet, the "standard" fingerings for high D#, high F, and high
F# are all quite flat.

Also, by the way, the partials get flatter and flatter as we go to shorter
tube fingerings. For example, if you play a throat E (E2). The first
partial is the high B (B3), and the next partial sounds a flat high G (G4).
In a perfect cylindrical narrow tube, it should have been a high G#. So
it is more than a half-step flat. Whereas the high C# (C3) played while
fingering low A (A1) is less than a quarter step lower than C#.

As we change fingerings on the clarinet we change the input impedance curve
of the instrument, so there is a different curve for each note.

For notes in the lower register, the largest resonance is the first
partial. When we open the octave key, we shift the position of the lowest
partial somewhat (putting it "out of alignment" with the other partials),
and we lower it's magnitude in the impedance curve such that the second
partial has the largest impedance now. That's why it's impossible to make
the low A (A1) sound, for example, while fingering E3.

As we go up to third partial fingerings such as high C# (C#3) or high D
(D3), we modify the impedance curve so that now the first =two= peaks,
corresponding to the first and second partials, are misaligned and reduced
in amplitude. Now the third partial is the highest peak. Again, fingering
a high C#, you can't sound E3, but fingering E3 you can sound a flat high
C#.

----------------

Jonathan Cohler
cohler@-----.net