Harmonic-series scale

What it means

The harmonic-series scale designates the sequence of notes that an instrument without keys, valves, or finger holes can produce — that is, the harmonic series above a fundamental, played in the order of its partials. It is not a scale in the usual sense, because its intervals become ever smaller going upward: first the octave and the fifth, then thirds, further up stepwise seconds.

Musical use

For the natural horn, the natural trumpet, the alphorn, and related instruments this is the entire available stock of notes. Their peculiarities follow directly from this: in the low register only a few, widely spaced notes are available, in the high register, by contrast, an almost complete scale. This is why the melodic passages of the older trumpet and horn literature lie high, while low notes are used for signals and sustaining sonorities. The horn fifths, too, are explained directly by this limitation.

Some natural notes deviate noticeably from the notes of the usual tone system; the seventh is the best-known case and sounds distinctly lower than the minor seventh. On natural instruments this was compensated by stopping or lip correction — or left as a characteristic sound, which has become an actual hallmark in alphorn melodies.

With the introduction of valves and keys, these instruments lost their limitation, and the harmonic-series scale receded as a shaping principle.

The sequence of notes corresponds to the overtones above a fundamental; from the eighth partial on, the notes lie stepwise next to one another. Some of these notes, especially the seventh, eleventh, and thirteenth, deviate markedly from equal temperament. Natural trumpet and natural horn can play only natural notes, which determined their melodic writing in the Baroque. Alphorn and overtone singing, too, rest on this material.

Performance practice

If you play older wind literature, look at the harmonic series of the respective fundamental — it explains why a passage looks the way it does. With natural instruments it holds: the deviating notes demand a decision about whether they are corrected or left as they are; make it deliberately and keep to it throughout the whole piece.