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What in tarnation is a "horn"?

I(1) mean a conical-bore brass instrument buzzed with the lips. But not a tuba.

We can speak of natural horns and valved horns. Natural horns have no valves, and are naturally near the harmonic series in their series of tones:

(fancypants graphic 1)

In 19th century technique, notes near the 7th and 11th harmonics were often written and could be finagled with different hand placements; even a C major scale in the lower octave could be negotiated. There was no avoiding an certain unevenness of tone, however.

To satiate the modulatory desires of classical composers, horns were soon made with a system of interchangeable crooks which, when inserted, would give a variety of keys. But this only encouraged the composers, and soon they were writing parts for two pairs of horns in different keys. Instrument builders tried in many ways to combine multiple keys into a single horn, settling finally on the rotary valve system prevalent in horns today.

So how does it work?

Well, there are three valves which the fingers of the left hand operates. The first valve causes the effective tube length to lengthen enough to lower the fundamental by a whole step (200¢). The second valve does the same, only by a half step (100¢), and the third, a minor third (300¢). In combinations these valves can lower the fundamental by up to a tritone.

So, the situation for a single F horn is something like this:

(fancypants graphic 2)

A double horn, on the other hand, has a thumb valve which switches between two keys, usually Bb and F. It does this by adding/subtracting an initial length of tubing and also (usually) with different lengths of tubes for the valves.

How can a horn play microtonal?

Hah! How can a horn not play microtonal? Horn players do a lot of hand adjusting to get their harmonic-series notes closer to equal temperament. If they were convinced to stop doing this, and also to play the harmonics that they usually don't (namely 7, 11, and 13), the horn might theoretically be capable of such a scale (notated in 72-edo):

(fancypants graphic 3)

On the other hand, a horn player can do a lot with his/her hand. How much? (fancypants sound file!)

So-called double horns (F horns with a Bb valve), go extremely sharp in the higher non-Bb-valve partials; the valve is used to get the upper register in tune. This means that these kinds of horns actually have a huge variety of intonation in the upper register through various combinations of valves. More than other brass instruments which are typically designed to have in-tune partials, and thus don't need that extra valve for tuning their high ranges.

Do you like quartertones? John Eaton has this useful tip from an interview in NewMusicBox: tune the F side a quartertone lower than the Bb side!

That's not good enough! We need new instruments!

You're right! George Secor especially has done some thinking about valve systems extended to alternate EDOs. See the bottom of this page. No cases of actual horns built...yet.

What existing music features the horn in a particularly microtonal way?

Further reading

  • Secor, George D. "An Approach to the Construction of Microtonal Valved Brass Instruments - The French Horn", Xenharmonikôn vol. 5, spring 1976, pp. 1-3.
  • Whaley, David Robert. The Microtonal Capability of the Horn. D.M.A. thesis, University of Illinois, 1975, 154 pages. University Microfilms, Ann Arbor MI, 1975.
  • Heim, David Bruce. Practical Tuning, Temperament and Conditioning for Hornists and Other Wind Instrumentalists: Understanding and attaining intonational flexibility in musical performance. Master thesis, University of Tulsa, 1990.


  1. Jacob Barton, I(2) think
  2. Mike Battaglia