The horn is a transposing instrument and unlike the trumpet sounds deeper than written in all tunings.
The modern horn is notated in F; in bass clef and treble clef it is written a fifth higher than it sounds.
Since the 1920s the practice of writing in concert notation for all instruments has become widely accepted, notably in the works of the Viennese School (Arnold Schoenberg, Alban Berg, Anton von Webern) and in serialism. The practice was introduced to make it easier to read complex scores, and there are numerous examples in 20th century literature. Stylistic developments that favored equal status for all twelve chromatic tones and avoided building around a particular key may well have been further factors that led to the use of the same notation for all instruments.
No key signature at the beginning of the staff
Unlike other transposing instruments such as the clarinet, the horn part – along with the trumpets and timpani – has always been written without key signature at the beginning of the staff. This tradition dates back to the beginnings of orchestral music and is still practiced today. Accidentals were extremely rare and were written into the score.
One peculiarity of horn notation is the signs used to indicate open and stopped notes: o = open, + = stopped.
Because the horns blend very well with the woodwinds, the horn part is found immediately below the woodwinds in the score, a place which would logically be occupied by the trumpet as the soprano instrument in the brass section.
In many 19th century scores the horn part, which was written in bass clef for low notes, was written a fourth lower than it sounded. This old style of notation – which was known as “high bass clef” – is no longer usual today. In new editions of old scores the horn part is generally rewritten so that the horn in F always sounds a fifth lower.
In line with the possibilities offered by the natural horn, only notes from a single natural harmonic series were available. Other pitches were very rare, because they could only be produced by stopping which resulted in a distortion of the timbre. The pitch of the horn was indicated in the score and the part was notated in C. Consequently most of the notation for the horn part corresponded to the natural harmonic series in C. Accidentals appeared only very rarely and were written into the score.
In classical symphonic music, a pair of horns was generally used for pieces in a major key, whereas two pairs were used for pieces in a minor key. This was done for harmonic reasons, since it was the only way to produce the second subject in the parallel major key.
Classical sonata movements really consist of two “themes” or “subjects”. These can be compared to two more or less active characters. The first “theme” is of course always in the principal key (tonic), the second in the most closely related, which is the one a fifth above it, the dominant. This applies to pieces in a major key. In pieces in a minor key the second theme is a third higher, in the parallel major key. But because the dominant in minor is in major on account of the leading note a “chromatic conflict” arises which could only be solved by one or two pairs of natural horns in different pitches. One of the horn’s main tasks was to support all the harmonically relevant tones (see for example W. A. Mozart, Symphony in G Minor, K.V.550).
In the course of time the two pairs of differently-pitched horns became standard in orchestration, as a result of which new harmonic possibilities – e.g. in modulations – were opened up for the instrument.
Today, four horns are standard in performances of the classical-romantic repertoire and their notation is written in pairs: the 1st and 3rd horns play the high part, the 2nd and 4th the low one. Two ways of summarizing the horn parts have gained acceptance:
1. The notation of the high (1st + 3rd) and low (2nd + 4th) horns is interlocking (Bruckner, Brahms and Wagner use this interlocking notation).
2. The high (1st + 3rd) and low (2nd + 4th) horns are notated on the same staff. Gustav Mahler, for example, uses this notation. Especially when one writes for 6 or 8 horns this usage is more convenient.
The way the horns are summarized depends in no small measure on the context.
The modern hornist must therefore answer the following questions before he begins to play:
- Is his part written for an F horn?
- Is his part written in the modern bass clef or the old high bass clef?
- Is the instrument playing the part (nowadays a horn pitched in F) pitched in the same tuning as the written part? (If not, the musician must transpose accordingly. For example, if a part written for a horn in E is to be played on a horn in F the hornist must transpose to F. If a part written in F is to be played on a horn in Bb – an instrument used only rarely today – transposition is also necessary.)